NL2017598B1 - Potted plants, and methods for their manufacture. - Google Patents

Abstract

The invention is in the field of agriculture and horticulture. More specifically, it is in the field of cultivating plants that require vernalization for germination and/or flowering. In particular, the invention relates to a method for producing a vernalized plant product that, upon replanting or outplanting, provides for a quick and beneficial cultivation result in the form of a flowering plant. The invention also relates to packaged plants produced by such a method and provides individuals with the possibility to grow flowers of vernalization-requiring plants at virtually any time of the year at a very short time of days to weeks.

Description

Title: Potted plants, and methods for their manufacture.

FIELD OF THE INVENTION

The invention is in the field of agriculture and horticulture. More specifically, it is in the field of cultivating plants that require vernalization for germination and/or flowering. In particular, the invention relates to a method for producing a vernalized pot plant of a flowering plant, that blooms upon replanting or outplanting. The method now provides for a quick and beneficial cultivation result in the form of a blooming pot plant. The invention also relates to packaged pot plants produced by such a method and provides gardeners the possibility to shape their garden with plants in bloom at any period of the year, even outside the blooming season of the plant.

BACKGROUND OF THE INVENTION

Ornamental plants are plants that are grown for decorative purposes in gardens and landscape-design projects, and include houseplants and cut flowers. The cultivation of such plants, also called floriculture, forms a major branch of horticulture. The ability to produce flowers from such ornamental plants at any desired time of the year is for instance needed when decorating important events, but is usually quite expensive, as it requires out-of-season cultivation.

It is generally known that certain ornamental plants require exposure to the cold of the seasonal winter to induce germination and/or flowering, generally to temperatures below 10 °C. This cold period breaks the dormancy and the associated process is called vernalization.

Ornamental garden plants that require vernalization, need to be placed in the soil well ahead of the winter, i.e. during the fall or autumn season or at the beginning of the preceding winter season that precedes their bloom period, so as the provide the seeds or bulbs with a sufficiently long cold period. This also directly implies that in certain countries, where the winter season is not characterized by prolonged cold periods, vernalizable flowering plants will not germinate and/or do not bloom.

Currently, in the Netherlands, there is a downward trend in the household share of dry ornamental bulb sales. It is suggested that people are less motivated to perform gardening activities in the fall season, with the result that the planting of ornamental bulbs is forgotten. This has already led to the fall season being named as “the forgotten season”. The required process of vernalization is inconvenient to normal consumers, and this is understandable, since gardening activities have to be performed well in advance of any visible result, and is therefore difficult to decide whether the planted bulbs will aesthetically match with the other plants in the garden.

From a consumer’s point of view, there is thus a need in the art to reduce the time from bulb or seed, to a blooming plant and, in addition, remove the need for the “old-fashioned” process of planting vernalizable bulbs or seeds during the fall season. This would be highly advantageous for garden landscaping purposes, as the location of the different flowers, their colors, and their combined appearance, can be tailored to a specific moment. In addition, this would result in a continuous availability of vernalized ornamental plants, throughout seasons, and would also provide for the possibility to grow vernalized ornamental plants in gardens of countries that do not have the cold-winter period needed for vernalization. It would for instance be possible to tailor the appearance of the garden to a specific theme, such as yellow for Easter and orange for Kings Day in the Netherlands. This all increases the effective cultivatable area of a garden.

The general desire to provide vernalizable, ornamental plants throughout the year, for instance during winter, is exemplified by the existence of so-called “ice-tulips”. These tulips represent cut flowers, the bulb for which are harvested the previous year, planted in boxes of generally 60-100 bulbs, frozen for a period of 6-12 months, made to bloom, and eventually harvested and sold as cut flowers. The quality of ice-tulips (cut flowers) is considered very low as compared to regular tulips (plant in bloom, optionally as cut flower, from a bulb that has not been frozen) and it is generally known that ice-tulip bulbs, due to their storage under frozen conditions, suffer from root rot.

An associated problem with cut tulips is that a retailer or household customer is unable to determine if the tulips are derived from ice-tulip bulbs or from regular, fresh bulbs. This is a problematic issue, because the two differ greatly in quality. It would be advantageous to the sale of tulips and other vernalizable ornamental plants if the consumer could determine from the face of the product whether the quality is acceptable.

Another problem with the commercial distribution of vernalizable ornamental plants, that is particularly notable in the case of tulip bulbs, is that the quality of the retail bulb is extremely poor. The dried and netted bulbs that are so in demand with, e.g., tourist, suffer from lack of producing flowers, or do not grow at all. Usually only a few percent of the tulip bulbs will produce flowers. Tulip bulbs are living produce and must actually be handled with care and stored cool and dry. This is not achieved in the case of netted bulbs, that are often exposed to moist and sunny conditions during retail sale.

As a result of the extreme conditions to which bulbs of garden tulips are exposed during retail sale, it is required that the quality of the bulb is very high, and correspondingly, the retail tulip for planting in household gardens, or garden tulip, is a high quality but very expensive bulb. It would be desirous to be able to provide the consumer, especially in retail channels, with a less expensive bulb, which bulb will still produce flowers in a household garden.

Another problem with the sale of such live produce as blooming vernalizable plants, especially from bulbs, is that the selling period is only very short. Generally, the selling period in retail is a mere one to two weeks for bulbs in pots, which is extended when using dried unplanted bulbs. It would be desirous to extend the selling period of such products.

It is a goal of the present invention to provide pre-vernalized plants for direct replanting or outplanting in gardens, preferably for commercial sale in retail channels, having the advantages as specified hereinabove, or at least not having the disadvantages described. It is noted that the invention is not limited to ornamental plants only, as also other plants, for example plants providing edible fruits, such as strawberry, require vernalization for development, and can be the subject of a method of the invention.

SUMMARY OF THE INVENTION

The inventors have now found that pre-vernalized plants can be provided for direct replanting by consumers when produced by a method of the present invention. The pre-vernalized plants thus produced, allow the sale in retail stores of pot plants that produce flowers within 1-4 weeks.

More specifically, the inventors solved the aforementioned problem by providing a method for the manufacture of a vernalized plant product of a vernalization-requiring plant species, comprising the steps of: a) providing a propagation material of a vernalization-requiring plant species, wherein said propagation material comprises at least one seed, bulb and/or rootstock, and wherein said propagation material has not been vernalized; b) developing said propagation material into a vernalized rooted plant by performing at least the following steps in any order: bl) planting said propagation material in a container comprising a substrate to provide a planted propagation material; b2)- allowing the planted propagation material to form a rooted plant comprising a rooting system in said substrate and at least part of a stem system; b3) subjecting said propagation material, said propagation material, or said rooted plant to a first cold-treatment for vernalization at a temperature of 0 to 10 °C, preferably for a period of 5 to 100 days, so as to provide a vernalized rooted plant; and c) subjecting said vernalized rooted plant to a second cold-treatment for arresting plant development and/or growth, wherein said second cold-treatment is at a temperature of -20 to -1 °C, preferably for a period of between 2 to 120 days; to provide a frozen vernalized rooted plant; d) optionally storing said frozen, vernalized rooted plant of step c) at a temperature below 0 °C; wherein step b) is adapted to provide a vernalized plant product comprising a frozen vernalized rooted plant suitable for outplanting in the form of 1-20 separable flowering units, and wherein the maximum period at which the frozen vernalized plant is below 0 °C during steps c) and d) together does not exceed 120 days.

In a preferred embodiment of a method of the invention, following step c) or d), said vernalized plant product is packaged in a packaging for display and sale of said vernalized plant product in frozen form.

In yet another a preferred embodiment of a method of the invention, the propagation material is subjected to a first cold-treatment for vernalization before planting.

In yet another a preferred embodiment of a method of the invention, the first and or second cold-treatment step occurs in a protected environment comprising a controlled temperature.

In yet another a preferred embodiment of a method of the invention, the vernalization-requiring plant is a bulbous plant, preferably a bulbous plant of the Liliaceae family, most preferably a tulip. Preferably, in aspects of this invention, the propagating material provided in step a) is in stage G.

In yet another a preferred embodiment of a method of the invention, said container is a biodegradable container, preferably a container for replanting or outplanting.

In yet another a preferred embodiment of a method of the invention, in step b) multiple seeds, bulbs and/or rootstocks are planted in a single container, preferably between 1-5 seeds, bulbs and/or rootstocks.

In yet another a preferred embodiment of a method of the invention, said container is a receiver unit including a multiple number of container volumes.

In yet another a preferred embodiment of a method of the invention, said container is a plant pot, preferably having dimensions of 5-20 (1) x 5-30 (w) cm.

In yet another a preferred embodiment of a method of the invention, said method further comprises the step of storing said container in a domestic refrigerator or freezer and/or the step of replanting or outplanting said container, preferably in a garden.

In yet another a preferred embodiment of a method of the invention, the maximum period at which the vernalized material is below 0 °C during step c) and d) is less than 14 weeks, preferably less than 13 weeks.

In another aspect, the present invention provides a vernalized plant product, obtainable by a method according to the present invention as described above.

In a preferred embodiment of a vernalized plant product of the invention, the container is for replanting or outplanting.

In another a preferred embodiment of a vernalized plant product of the invention, said propagating material is individually planted for replanting or outplanting in a biodegradable container.

In yet another a preferred embodiment of a vernalized plant product of the invention, said packaging or container includes a color or color code so as to indicate the color or colors of the flower of the plant.

In yet another a preferred embodiment of a vernalized plant product of the invention, the container comprises a layer of a porous medium covering the substrate.

In yet another a preferred embodiment of a vernalized plant product of the invention, the vernalized plant product comprises a single frozen vernalized plant or a set of two frozen vernalized plants, preferably wherein said set of two plants are planted in separate containers or in a single container.

In another aspect, the present invention provides a packaging comprising a vernalized plant product of the present invention as described above, preferably wherein said packaging is for storage of frozen products.

In another aspect, the present invention provides a refrigerator or freezer comprising the vernalized plant product according to the present invention as described above, or the packaging according to the present invention as described above.

The aspects of the invention as disclosed above provide individuals with the possibility of growing flowers of vernalization-requiring plants at virtually any time of the year at a very short time of only days to weeks, without the necessity of planting the propagating material, such as tulip bulbs, in the autumn.

DESCRIPTION OF THE DRAWING

By way of example only, embodiments of the present invention will be described with reference to the accompanying drawing in which

Fig. 1 shows a schematic view of a packaged, vernalized plant according to the invention. The figure merely illustrates a preferred embodiment according to the invention. DETAILED DESCRIPTION OF THE INVENTION Definitions

The term “vernalized” or “vernalization”, as used herein, refers to the process of promoting the development of a plant in terms of germination and/or flowering. More specifically, the term refers to the “acquisition or acceleration of the ability to flower by a chilling or cold treatment”. The term covers plants for which the process of vernalization is essential to achieve flowering, and plants for which a period of cold leads to improved flowering, inter alia in these sense that (i) time to flowering is reduced, (ii) flower number per plant is increased and/or (iii) more uniform flowering is achieved. This treatment can be natural or artificial. Hence, in aspects of this invention, the first cold-treatment need not occur in a controlled environment, but may occur outside, as a result of climatic influence. Preferably, however, vernalization occurs under controlled conditions. After vernalization, vernalization-requiring plants do not necessarily initiate flowering, but acquire the ability to do so. In many plant species, vernalization requires long-term exposure to the low temperatures of a typical seasonal winter. In vernalization-requiring (or “vernalizable”) plant species, it is preferred that the plants are not induced to flower in the late autumn season as a result of short, transient exposure to a cold period, followed by exposure to warmer conditions, as this will result in flowering. Flowering of many vernalization-requiring plant species is also promoted by long photoperiods (exposure to light) and this photoperiod requirement provides another level of assurance that flowering does not occur in late autumn when the days are short. The vernalization thus represents a rest period (preferably at a temperature of between 0 to 10 °C, preferably for a period of 5 to 100 days) that is required for the plants to flower or bloom.

The term “plant”, as used herein, refers to a plant, or part thereof, of a species that requires the process of vernalization to acquire or accelerate the ability to flower. The term “plant”, as used herein, is preferably defined as comprising a root system (penetrated) in a substrate, and at least part of a stem system. A bulb herein represents a stem system. The terms “plant”, “seed”, “rootstock”, and “bulb”, are used in their art-recognized meaning.

The term “root system”, as used herein, refers to the root structure of a plant, which, when said plant is planted in a substrate, is typically penetrated into said substrate.

The term “stem system”, as used herein, refers to the stalk of a plant or the main trunk of a tree. A stem system may include, but is not limited to, bulb, stalk, stock, shoot, trunk and axis. A shoot is used herein to describe new plant growth that can grow from seed or axillary buds. A shoot may include but is not limited to: branch, bough, growth, offshoot, sprig and scion. Stems and shoots are node-bearing plant structures. The skilled person is well aware how to determine whether a plant has a root system and a stem system.

The term “bulb”, as used herein, may refer to either its meaning in botany or in gardening, or both. In botany, a bulb is a short stem with fleshy leaves or leaf bases that function as food storage organs during dormancy.

In gardening, plants with other kinds of storage organ are also called "ornamental bulbous plants" or just "bulbs". The leaf bases of a bulb, also known as scales, generally do not support leaves, but contain food reserves to enable the plant to survive adverse conditions. At the center of the bulb is a vegetative growing point or an unexpanded flowering shoot. The base is formed by a stem, and plant growth occurs from this basal plate. Roots emerge from the underside of the base, and new stems and leaves from the upper side. Bulbous plant species cycle through vegetative and reproductive growth stages; the bulb grows to flowering size during the vegetative stage and the plant flowers during the reproductive stage. Certain environmental conditions are needed to trigger the transition from one stage to the next, such as the shift from a cold winter to spring. Once the flowering period is over, the plant enters a foliage period of about six weeks during which time the plant absorbs nutrients from the soil and energy from the sun for setting flowers for the next year. Bulbs dug up (or lifted) before the foliage period is completed will not bloom the following year but then should flower normally in subsequent years. After the foliage period is completed, bulbs may be dug up and harvested for replanting elsewhere. Any surface moisture should be dried, then the bulbs may be stored up to about 4 months for a fall planting. Storing for much longer than 4 months may cause the inside of the bulbs to dry out and become nonviable. After bulbs are harvested, a new flower develops inside the bulb. Flower development occurs in various developmental stages. First, the petals are formed, thereafter the stamens, and finally the pistil. Following these developments, a complete flower is formed and exists in embryo in the bulb. This is called ‘Stage G’, for “Gynoecium”. In order to examine if a bulb is at stage G, a sample bulb can be examined under a microscope using a longitudinal section. G stage is the stage at which the gynoecium (the female flower parts, made up of one or more carpels, consisting of stigma, style and ovary) are well-formed, following the development of perianth and the androecium (stamens).

Hence, at stage G, the flower has fully developed inside the bulb. It is preferred that the bulb used in aspects of this invention prior to receipt of the first cold treatment is at stage G. Moreover, it is preferred in embodiments of this invention that the bulb used in aspects of this invention prior to receipt of the first cold treatment is a harvested bulb that has optionally received additional treatment (such as drying or heating).

The term “substrate”, as used herein, refers to the medium on which a plant grows and in which its roots are distributed. The substrate preferably provides the plant with nutrients such as water and minerals. A substrate can be a soil, preferably a potting soil - also referred to as a potting mix or potting compost. A wide array of soils or other substrates are available for cultivating plants. A substrate in aspects of this invention is not necessarily a soil. The skilled person is well aware of methods and means for cultivating plants without soil, inter alia encompassing “hydroponics”. A suitable substrate in that context may for instance be a mineral or polymer. Other, or additional, means for soilless culture is the use of an inert medium such as perlite, gravel or rockwool.

The terms “seed”, “bulb” or “rootstock”, as used herein, refers to seeds, bulbs or rootstocks, respectively, that require the process of vernalization to germinate and/or flower, by exposure to a cold treatment. A rootstock may refer to a rhizome or an underground stem.

The terms “flowering” or “to flower” as used herein, refers to the blooming or formation of flowers of flowering plants. A “flowering unit” refers to a single seed, bulb or rootstock that, when vernalized and placed under suitable conditions, produces at least one flower.

The term “container”, as used herein, refers to a container for plant husbandry, i.e. a container suitable for cultivating or displaying at least one plant in a substrate. The container is preferably a plant pot and is more preferably a plant pot adapted or developed for placement in soil such as in a garden while containing the plant. In that context the container or plant pot is preferably biodegradable, and may be based on coco or peat/turf, or any other biodegradable material. Suitable examples of such biodegradable plant pots include pots of the line Jiffypot®. In the context of the invention, wherein plants of the invention are produced and packaged for planting in the soil of inter alia a garden, it is beneficial that the container is biodegradable, as such a composition of the plant pot limits the physical obstruction of root distribution normally caused by plastic or terracotta plant pot material. Another advantage of a biodegradable pot is that it is not necessary to dig it out of the soil after a plant of the invention stops flowering or has died. This is especially beneficial in that the cultivatable area of the garden is indeed effectively increased due to the absence of garden volume-occupying containers in the soil. The container may suitably be a receiver unit including a multiple number of container volumes. For example, the receiver unit includes partitioning members, defining the container volumes, e.g., a one- or two-dimensional array of container volumes. The receiver unit may be replanted our outplanted in its entirety (as a whole), or as a multiple number of separate submodules. To that end, the receiver unit may be disassembled into a multiple number of individual containers for outplanting or replanting. To facilitate the disassembly, the receiver unit may be provided with breaking lines between individual container volumes, e.g., along the partitioning elements.

The term “outplanting” as used herein, refers to the process of moving the growing location of a plant to a location where it is allowed to flower. Outplanting may occur in an inside or outside soil, such as a garden soil. Alternatively, outplanting may refer to placing a plant of the invention in a windowsill or in a pot on a table. It is an aspect of this invention that products are suitable for outplanting in the form of 1-20 separable flowering units. As an example, this means that 1 to 20 bulbs, preferably 1-3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 tulip bulbs have been planted and grown in containers such that individual frozen bulbs can be separated from, for instance, a tray of bulbs, without damaging the roots of the individual bulb. This allows packaging of individual frozen vernalized plants (bulbs) and individual sale and display-for-sale, but also outplanting of any desired number of bulbs, alone, or in groups of e.g. 20, in any arrangement or color combination as desired. Thus, it is an aspect of this invention that individual frozen plants can be packaged and sold, so as to provide a novel product for the retail market. This individual packaging can for instance be accomplished by breaking off individual plants from a frozen tray consisting of adjacent containers that are interconnected through a separable (e.g. perforated) connection. It is especially envisaged in this preferred embodiment of products suitable for outplanting in the form of 1-20 separable flowering units as described herein that the container is a receiver unit including a multiple number of container volumes. For example, the receiver unit includes partitioning members, defining the container volumes, e.g., a one-or two-dimensional array of container volumes. The receiver unit may be replanted our outplanted in its entirety (as a whole), or as a multiple number of separate submodules. To that end, the receiver unit may be disassembled into a multiple number of individual containers for outplanting or replanting. To facilitate the disassembly, the receiver unit may be provided with breaking lines between individual container volumes, e.g., along the partitioning elements.

The term “retail channel”, as used herein refers to selling locations from which households purchase their commercial plants or propagating material, such as garden centers or supermarkets, or any other suitable outlet capable of vending from freezers.

The term “cold-treatment for vernalization”, as used herein, refers to a cold period of sufficient length and of sufficiently low temperature to confer upon the vernalization-requiring propagating material the ability to germinate and/or flower. The vernalization temperature is preferably 0—10 °C, more preferably 2-9 °C. This period is also referred to herein as the first cold-treatment. The vernalization temperature may also be a set of different temperatures between 0-10 °C, such as an initial first period of vernalization at a temperature of 7-10 °C, such as about 9 °C, for a period of between, for instance, 5 to 50 days, followed by a subsequent second period of vernalization at a temperature of 1-4 °C, such as about 2 °C for a period of between, for instance, 5 to 50 days. Such an initial first period of vernalization may, for instance, have a duration of 2-6 weeks, such as 3, 4 or 5 weeks, and a subsequent second period of vernalization may, for instance, have a duration of 2-6 weeks, such as 3, 4 or 5 weeks. The vernalization temperature may, in an alternative embodiment, comprise a gradual decrease in the temperature to which the propagating material is exposed in accordance with aspects of this invention, for instance from a temperature of 9 °C down to 2 °C, i.e. along a decreasing temperature gradient, suitably over a period of, for instance, 1, 2, 3, 4, 5 or 6 weeks or longer. The gradient may, but need not be, constant. In aspects of this invention, plants are not devernalized before planting. The cold-treatment for vernalization is herein also referred to as the first cold-treatment.

The term “planting”, as used herein, refers to placing a propagating material such as bulbs in or onto substrate, such as soil. Sowing is the process of planting seeds. In sowing, little if any soil is placed over the seeds. More precisely, seeds can be generally sown into the soil by maintaining a planting depth of about 2-3 times the size of the seed. Seeds may be pre-treated prior to planting by any seed-treatment method available. A bulb in aspects of this invention is preferably planted in suitable substrate, such as a potting soil, and the planted bulb is preferably thereafter covered with a small layer of sand, or another porous medium (e.g. gravel), so as to prevent emergence the of the bulb during formation of the root system.

The term “cold-treatment for arresting plant development and/or growth”, as used herein, refers to a period of cold sufficient to arrest plant development and/or growth. This cold-treatment is preferably at a temperature of -20 °C to -1 °C (minus 20 to minus 1 °C). This period is also referred to herein as the second cold-treatment.

The term “for replanting or outplanting”, as used herein, refers to the type of container in which the plant contained after planting. The container is preferably such that a minimum number of steps is needed to plant a plant of the invention in soil, such as in the soil of a garden, or a decorative pot in a room. A plant of the invention in a container is preferably provided with a packaging for transporting frozen goods, such as paper- or plastic-based packaging materials including carton, paperboard or corrugated fiberboard boxes or transparent containers or wrappings. The container holding the plant, or the packaging holding the container, preferably contains a color or color code corresponding to the color of the flowers of the plant in said container holding the plant. The packaging is also suitably transparent. The container is preferably biodegradable, such that it can be placed in the soil of a garden in its entirety together with the plant. The rooted plant is preferably not removed from its container, prior to planting, so as to avoid damage to the root system. Replanting as referred to herein, includes the process of removing the rooted bulb together with the substrate from its container, and replanting it in soil or a different pot. Outplanting, as referred to herein, refers the process of moving the plant from a nursery bed, greenhouse, or other location to a different location fpor flowering, such as an outside area, preferably into a soil, e.g. of a garden, while leaving the plant in the container. Outplanting in the context of this invention includes reference to moving the frozen or thawed potted plant in its entirety to an indoor location for flowering. “Flower bulbs” refers to all taxa of ornamental flowering “bulbs” having true bulbs, corms, tubers, rhizomes, tuberous roots, or enlarged hypocotyls as underground storage organs (Le Nard, M., and A.A. De Hertogh. 1993. Tulipa. In A. De Hertogh and M. Le Nard, eds., The Physiology of Flower Bulbs, pp. 617-682. Elsevier Science Pub., Amsterdam, Netherlands.). All of them are geophytes, a term that not only includes flower bulbs but also most herbaceous perennials, some fruits such as strawberries, and some vegetables such as asparagus. Commercially, over 60 taxa and thousands of cultivars of flower bulbs are grown on approximately 32,000 hectares (Le Nard, M., and A.A. De Hertogh. 1993. Bulb growth and development. In A. De Hertogh and M. Le Nard, eds., The Physiology of Flower Bulbs, pp. 29-43. Elsevier Science Pub, Amsterdam, Netherlands). However, six genera make up over 90% of the total acreage of bulbs produced. In 2000, the world production of flower bulbs was: Tulipa, 39%; Narcissus, 20%; Lilium, 19%; Gladiolus, 8.5%; Hyacinthus, 4%; and Iris, 3%. A preferred embodiment of a bulb in aspects of this invention is a tulip. Tulips are spring-blooming perennials that grow from bulbs.

The term “ornamental plant”, as used herein, refers to plants that are grown for decorative purposes in gardens and landscape design projects, as house plants, for cut flowers and specimen display. More specifically, the term refers to garden plants or plants that are sold for cultivation and display in a garden.

The term “bulbous plant”, as used herein, refers to a plant growing from a bulb. A preferred bulb of the invention is a bulb of a Liliaceae plant, most preferably a bulb from a species of the genus Tulipa. Flowering bulbs of the invention may be annuals, biennials, or perennials, and may bloom in spring, summer, or autumn, which periods refer to the plants natural blooming period. Tulip preferably refers to Tulipa gesneriana L.

The term “refrigerator or freezer”, as used herein, preferably refers to a refrigerator or freezer generally encountered in house-holds or in retail such as supermarkets. The refrigerator or freezer can be free-standing or build-in. In addition, multiple refrigerating or freezing units may be disposed side to side, or in line, as generally is the case in retail.

The term “frozen”, as used herein in the context of frozen plant, refers to a plant having an internal and/or external temperature below 0 °C, or refers to plants that are stored at a temperature of below 0 °C.

Description of the preferred embodiments

Embodiments described herein for bulbs, equally apply to other forms of propagating material described herein.

Although springtime flowering bulbs are best known, some bulbs bloom in summer and autumn. The wide variety of blooms and foliage produced by flowering bulbs make them very desirable in garden designs. Bulbs are very aesthetic in flower beds or containers, and are often used to accent other plants when grouped together. Choosing the right flowering spring, summer, or autumn bulb is possible, but requires careful planning and horticultural preparation by planting of selected bulbs well in advance of the flowering season. In order to ease the production of flower arrangements, the present inventors now provide for a method using frozen potted flowering plants. In this way, the horticultural preparation can be delayed until just a few days or weeks prior to the intended blooming time.

The present invention thus provides for a method for the production of flower arrangements, comprising a method using frozen potted flowering plants, and a process for producing frozen potted flowering plants. Processes for producing cut flowers, such as cut tulips, are well known in the art, as are methods of producing early flowering plants, such as tulips from bulbs. Methods for producing cut flowers, and methods for producing early flowering plants are not an aspect of this invention.

Depending on their intended use, there are essentially three types of bulbs: planting stock, forcing bulbs, and garden and landscaping bulbs. Planting stock is intended for maintaining the variety, for asexual reproduction through bulblets, and for increasing the size (or weight or quality) of the bulbs. Planting stock is generally allowed to bloom for about three weeks, after which the flower is topped to control petal debris and to avoid energy-loss to seeds.

Forcing bulbs are produced for forcing as fresh cut flowers. Forcing bulbs are usually small, planted closely together in large trays, vernalized, and allowed to bloom, after which the stems with flowers are harvested.

Garden and landscaping bulbs are generally of large size and high quality and are produced for use in gardens or pots and sold in harvested (lifted), dried and non-vernalized form in retail channels.

Not only do the various bulb-types described above follow different routes to flowering due to a different processing, they are generally also of a different quality. Hence, a forcing bulb is not generally suitable for use as a garden and landscaping bulb in retail. In aspects of the present invention, it is intended that both forcing bulbs (which are generally of a smaller size) and garden and landscaping bulbs can be used.

Many bulbs, including tulip bulbs, may suffer from Fusarium and Penicillium infection and many cultivars are susceptible to flower abortion and abnormalities due to ethylene exposure or exposure to unfavorable storage conditions such as in retail displays (e.g. heat, drying). Regardless of the horticultural use, conventional bulb products are therefore preferably shipped at 17 °C under a ventilation rate of 150 m3.h·1. With the exception of a treatment at 34 °C for early forcing, unplanted bulbs are not to be stored at temperatures exceeding 25 °C or temperatures lower that 0 °C. It is an advantage of the present invention, that these problem can now be circumvented by the use of the vernalized plant product of the invention.

Due to the fact that the vernalized plant product of the invention is displayed and sold in frozen form, fungal infection is prevented, and unfavorable display conditions that result in flower abortion are prevented.

After being harvested, bulbs for planting stock are initially placed at 23 to 25 °C for 3 to 4 weeks. Subsequently, depending on the cultivar, they are stored at progressively lower temperatures, from 23 to 20 °C down to 17 to 15 °C, until just before being planted. These temperatures are used to encourage enhanced production of large sized bulbs from the planting stock. Such conditions may suitably be used in aspects of the invention to provide bulbs at stage G (Rees, 1973. J. Hort Science 48:149-154).

For very early forcing, or early flowering, of forcing bulbs, most cultivars may be kept at 34 °C for a duration of 1 week immediately after lifting. Subsequently, they may be stored under dry and ventilated conditions at 17 to 20 °C. Such conditions may suitably be used in aspects of the invention to provide bulbs at stage G. It is preferred to be able to identify the stages of flower initiation, since the bulbs must reach stage G prior to the first cold treatment in accordance to the present invention.

For medium and late forcing, bulbs are generally placed at 17 to 23 °C prior to vernalization. Such conditions may suitably be used in aspects of the invention to provide bulbs at stage G prior to their exposure to the first cold treatment in accordance to the present invention.

Although forcing of bulbs may ensure the availability of flowering bulbs much earlier in the year, forcing in general is not the solution for obtaining flowering bulbs at any time of the year, because forcing bulbs are usually harvested in areas with a warmer climate than that of the country or market for which the early flowering bulb plant is intended. Warmer climates at the production locations result in faster growth of the bulbs and an earlier harvest, but does not provide for the advantages of the present invention. A disadvantage of forced bulbs is that, once vernalized, their development will continue, and they have a limited shelf-life and time-to-market.

In order to influence the flowering date of bulbs, for example in order to ensure that bulbs bloom during Christmas, New Year, Valentine’s Day, Easter, or any other date prior to the natural flowering date, it is preferred in aspects of the present invention to cool or heat the bulbs under controlled conditions.

The process of vernalizing seeds, bulbs or other plant material with a first cold-treatment.

The invention relates to plants, or plant parts, that require the process of vernalization to acquire the ability of, or accelerate/improve the process of, germination and/or flowering. A diverse group of plants - some of ornamental nature, others more functional, such as plants providing edible fruits or other edible plant parts - require vernalization for flowering or for improving the process of flowering.

The skilled person is well aware of plant groups or plant species that require, or benefit from, vernalization. Preferably, the plant is selected from the group of vernalizable bulbous plants, such as bulbous plants of the Liliaceae family, or the subfamily of Lilioideae, which includes the genus

Tulipa and subgenera thereof such as Clusianae, Orithyia, Tulipa and Eriostemones. Other plants in the Liliaceae family are lilies. Other suitable vernalizable plants are found in the family of Amaryllidaceae, which includes plants of the genus Narcissus. Other suitable vernalizable plants are bulbous perennial plants of the genus Muscari such as Muscari botryoides, also known as grape hyacinth, or strawberry. A plant of the invention is preferably a tulip, lily, narcissus, grape hyacinth and/or strawberry. More preferably, a plant of the invention is a tulip.

Vernalization-requiring plant-species, such as tulips, must undergo a so-called “cold period” in order to develop long stems and to be able to flower. If the bulbs are planted in an area with cold winters, they will receive a natural cold period. However, when the bulbs of vernalization-requiring plants are placed in a cooling room before the winter months, they can flower earlier than their natural flowering date. This is what in the art is call “forcing”. Thus, “forcing” is defined as placing in a cooling room before the winter months, to achieve that bulbs flower earlier than their natural flowering date. In some embodiments of aspects of this invention, the invention comprises the step of “forcing”.

Vernalization-requiring bulbs are preferably exposed to a warm period prior to the cold period of vernalization, so that the flower inside the bulb can develop, and the bulb can reach stage G. This may occur in the controlled environment of a treatment room in which bulbs are heated or warmed at a specific temperature until reaching developmental stage “G” (Rees, 1973. J. Hort Science 48:149-154). Vernalization may be initiated after the bulbs have reached stage “G”.

The process of vernalization according to the present invention involves subjecting a propagation material, such as a seed, bulb, or other plant part, such as rootstock, before, during or after planting said material, preferably before planting, to a cold-treatment at a temperature of 0 to 10 °C, preferably at a temperature of 5 to 9 °C. The term “to” when reference is made to a specific range, includes reference to the end points of that range.

The process for the production of a vernalized frozen plant according to the present invention comprises two cold treatment periods.

The first cold treatment period comprises the vernalization and root formation, the second cold treatment period comprises the freezing and arrest of development.

Bulbs subjected to the first cold treatment should be kept at a temperature that allows the roots to develop. This process of root formation generally takes at least three weeks, but may be chosen longer or shorter, depending on the species, variety, stem length and time of flowering required. Generally, a temperature between 0 and 10°C, preferably 2-9°C, will allow root formation.

The first cold-treatment can be provided by any means, such as by placing the propagation material in a refrigerator or cold room. As disclosed herein, the cold treatments proposed are artificial in the sense that they are not provided by nature as seasonal cold periods of temperate climatic zones. Preferably, the cold treatments occur in a protected environment having a controlled temperature, such as a cooling chamber, preferably comprising means for controlling the temperature of said environment independent of the outside climatic conditions ,. Preferably, the environment wherein the material is cold-treated is ventilated with air.

The period of the first cold-treatment is preferably 2-140 days, more preferably 10-100 days or 25-100 days, even more preferably 30-90 days and most preferably about 70-85 days. It is preferred that the length of the first cold treatment period is kept relatively short so as to keep the stem of the resulting flowering plant short but firm. A short but firm stem is particularly important for, for instance, garden tulips. A shorter first cold treatment period provides a shorter firm stem. Thus, the vernalization period of the plant of the present invention is preferable chosen such that a relatively short firm stem is obtained that is suitable for outdoor exposure. This adaptation of the length of the first cold treatment to thereby direct the length and firmness of the stem of the flowering plant, now allows the use of the bulk lower “industrial” quality forcing bulbs, such as used for producing “ice tulips”. The duration of the first cold-treatment period is preferably adapted such that the flower stem at the fully grown flower is less than 70cm, preferably less than 60 cm, 50 cm, 40 cm, 30, cm, 25 cm, 20 cm, or 20 cm. Preferably, the duration of the first cold-treatment period is adapted such that the flower stem length of the fully grown flower is the range of 15-50 cm, preferably 20-40 cm, more preferably 25-35 cm.

The temperature during this first cold-treatment may be constant, such as a 5°C, but preferably the temperature during the first cold treatment is lowered gradually, over a period of several weeks in the form of a descending gradient, preferably over the whole period of the duration of the cold treatment, from a temperature of 8-10°C, preferably around 9°C, down to a temperature of 1-3°C, preferably down to 2 °C. It was found that the provision of a descending temperature gradient provides for improved storability during freezing and increased quality of the resulting flower bulb and flower.

The skilled person will understand that propagation material in aspects of this invention can be vernalized without having yet been planted in or on a substrate such as a potting soil. It is preferred, in one embodiment of aspects of this invention, that the process of vernalization is applied on a propagation material before it is contacted with, or planted in or on a substrate.

In an alternative embodiment, it is preferred that the process of vernalization is applied on a propagation material after or at least partly during a period when said material is contacted with, or planted into or on a substrate. The substrate is preferably contained in a container.

It is part of the inventive concept to allow the propagation material, after planting, to form a root system, preferably in a substrate. This can, in one embodiment, suitably occur within the period of the first cold-treatment. Alternatively, allowing the propagation material to form a root system may occur after the period of the first cold-treatment, wherein the planted and vernalized propagation material is subjected to an elevated temperature as compared to the temperature of the first-cold treatment, for instance a temperature in the range of 12-30 °C, preferably 12-20°C. The skilled person will understand that the period in which the planted propagation material is subjected to such an elevated temperature should be sufficient to allow the planted material to form a rooted plant comprising a rooting system in a substrate, and optionally at least part of a stem system. In this manner, a vernalized plant of the invention is primed to quickly grow and flower. In this stage, the vernalized plant germinates, develops roots and part of a stem system, but is non-flowering. In other words, a rooted plant in that stage is still in its vegetative or juvenile stage and is not flowering. Preferably, the formation of such a rooted plant occurs during the first cold-treatment.

Generally, the first-cold period is preferably initiated after the propagating material reaches stage G. It is possible to expose the propagating material prior to the first cold-treatment, and after reaching stage G, to a temperature of about 15-25 °C, preferably about 20 °C, for a period of between 1-5 weeks, such as 2, 3, or 4 weeks. This brief, relatively warm period is preferably provided to the harvested, dried propagating material in stage G.

In a preferred embodiment, only a single flowering unit of propagation material (such as a single seed, bulb or other plant part that can grow in a mature plant), is planted in or on a substrate in a container and allowed to form a rooted plant comprising a rooting system in a substrate, and optionally at least part of a stem system. It is, however, also envisaged in other embodiments envisaged herein that more than one flowering unit of propagation material (such as multiple seeds, bulbs or other plant parts that can grow in a mature plant), is planted in or on a substrate in a container. Preferably, 2-10, more preferably 2, 3, 4, or 5 flowering units of propagating material, such as seeds or bulbs are planted in a single container in accordance to embodiments of this invention. A flowering unit herein is a unit of propagating material that forms at least one flower. The propagation material that is planted is preferably of the same plant species, but may be of a different cultivar or variety. Alternatively, when planting multiple flowering units of propagating material per container, the container may comprise propagation material of different plant species that form a root system in a substrate, and optionally at least part of a stem system.

In general, as is deducible from the above, it is noted that a method for producing a plant of the invention may also refer to a method for producing more than one, or at least one, vernalized plant, possibly of a different species, that are in the same container, i.e. in a single plant pot.

It is a disadvantage of the methods of the prior art, that when multiple flowering units of propagation material are planted together in high numbers in relatively large containers and are allowed to form a root system, that their root systems become entangled. This inhibits easy separation of individual or a relatively small number of flowering units. Hence, it is preferred that the propagating material prior to the first cold-treatment period is planted in small numbers, preferably individually, i.e. one, or with 2-4 flowering units, at most, in a single pot, or in individual sub-containers. The skilled person will understand that physical separators may also be used when using larger trays, so as to physically separate the root systems of a single flowering unit or of no more than 2-4 plants flowering unit adjacent flowering units. It is thus suitable to use a tray with compartments, preferably removable compartments.

It is also envisioned that multiple flowering units (e.g. plants) are separated by the use of physical separators in a planting tray that at least partially separate the growing substrate of one flowering unit from the growing substrate of an adjacent flowering unit, such that these flowering units, when contained in their substrate can be broken apart or divided.

This has the advantage that any desired number of plants can be outplanted in accordance with this invention in, for instance, a garden. In this way, an arrangement of individual plants according to this invention can be outplanted, or an arrangement of 2-20 or more plants can be outplanted as a single outplanting element. When plants of the invention are outplanted, they may be outplanted with or without the planting pot.

Arresting plant develonment/growth with a second cold-treatment A further step of a method of the invention involves subjecting a rooted plant as mentioned hereinbefore to a second cold-treatment for arresting plant development and/or growth. Again, a refrigerator or freezer, preferably also providing ventilation of air, can suitable be used for this purpose. The temperature of said second cold-treatment is sufficient to arrest plant development and/or growth and is preferably below 0 °C, more preferably below -1 °C, even more preferably in the range of -20 °C to -1 °C, and most preferably in the range of -10 °C to -1 °C. The inventors established that a temperature of about -1 °C, or lower, very suitably arrests plant development and/or growth.

The period of the second cold-treatment is such so as to arrest the development and/or growth of the rooted plant. Preferably, the period of the second cold-treatment is 2-120 days, more preferably 2-60 days or 2-30 days. The period of the second cold-treatment should not exceed 5 months, preferably it should be less than 4 months, more preferably less than three months, as it was established that prolonged periods of freezing, i.e. periods longer than 5 months, reduce plant or flower quality and increase the susceptibility of said plant to root rot. The duration of the period during which the vernalized propagation material remains frozen, prior to its sale and outplanting, e.g. in a garden, is suitably 15-16 weeks. Preferably, the vernalized propagation material remains frozen for a period less than 14 weeks, more preferably less than 13 weeks, e.g. 12 weeks, in order to obtain relatively short, relatively strong stems. The skilled person understands that this condition does not only apply to the period of the second cold-treatment, but in fact applies to the combination of the period of the second cold-treatment and the period in which a packaged plant of the invention is stored, transported to the retailer, and displayed for sale. Said storage, transport and display preferably also takes place under freezing conditions, i.e. at temperatures below 0 °C.

Storing a frozen, vernalized plant of the invention.

After subjecting a plant to the second cold-treatment, the plant or plants in a container for replanting or outplanting are optionally packaged, and then stored at a temperature of below 0 °C. The skilled person understands and envisages that the step of the second cold-treatment and the step of storing the frozen plant can, in fact, be one step wherein the rooted plant is subjected to a second cold-treatment for arresting plant development and/or growth and at the same time is stored under the temperature applied during the second cold-treatment. It is preferred that these steps are executed simultaneously. Storage of the frozen plant preferably occurs by non-natural or artificial means for cooling such as in a freezer. The period during which the vernalized propagating material s kept frozen (ie.e before it is sold and outplanted in, e.g., a household garden, is preferably not more that 6 weeks to 3 months. This period should not exceed 6 months.

Packaging a plant of the invention A further step of the invention involves packaging a frozen, vernalized plant of the invention. A frozen, vernalized plant of the invention is planted in a container for replanting or outplanting. In other words, a frozen, vernalized plant of the invention is in a container, preferably in a biodegradable plant pot, and may thereafter be packaged in for instance a box or another packaging type. The consumer can easily replant or outplant the plant in the container by planting the plant in the container in soil such as a garden.

An advantage is that the availability (year-round) of vernalized plants in gardens is strongly increased, as, for instance in spring and summer, new frozen, vernalized plants can be planted whenever it is desired. By virtue of the present invention, it now, for instance possible, that prior to Easter, a set of frozen vernalized yellow tulips according to the present invention, which ae non-flowering at that moment, are planted in a garden so as to flower during Easter, during which time yellow is a popular coloring arrangement. After Easter, the yellow tulips can be removed from the garden, and a set of frozen, vernalized orange tulips can be planted that is anticipated to flower a month later, during, e.g., King’s Day in the Netherlands, during which time orange is a popular coloring arrangement.

It is clear that the effective cultivatable area of a garden is increased with the present invention, as the time until flowering in a garden is drastically shortened.

The bulbs of the present invention are preferably packaged.

Figure 1 shows a schematic view of a packaged, vernalized plant 10 according to the invention. The plant 10 has a bulb 12, a stem 14 extending upwardly from said bulb 12, and a rooting structure 16 extending from said bulb 12 downwardly and sidewardly. Aternatively, the stem 14 may be (part of) the bulb 12, as in the case of tulip bulbs, the stem is botanically considered to represent the stem. The bulb 12 and the rooting structure 16 are embedded in a substrate 18 such as soil or a synthetic medium e.g. hydroponics. The substrate 18 is contained in a container 20. As shown in Fig. 1 the stem 14 extends upwardly such an upper part of the stem is located above the substrate 18. However, the stem can be shorter such that it is completely covered by the substrate 18. Further, the stem might have relatively short dimensions such that it might be even hardly visible.

In the embodiment shown, the container 20 contains a layer of sand or another porous medium 22 covering the substrate 18. In another embodiment, however, no sand or porous medium is applied on top of the substrate 18. Optionally, a moisture impermeable or less permeable foil can be applied covering the content of the container 20. The foil may seal the container 20 to minimize an evaporation process. In the shown embodiment, no foil is applied e.g. in case of a relatively short storage time of the plant 10.

Generally, the container 20 may have a cylindrical geometry, e.g., having a polygonal or rounded cross sectional shape. As an example, the container has a rectangular, square or circular cross sectional shape. It is noted that the container may have another geometry, e.g., a ball shape.

In Fig. 1 the container 18 has been placed in a packaging such as a box or bag 24 for packaging the plant 10 so that customers may easily handle the container with reduced chance of damaging the plant 10. In principle, the packaging may contain a single container 18 or a multiple number of containers e.g. two, three, four or five containers. Further, the container 18 may include a single plant 10 or some more plants, preferably 2-10 plants, more preferably 2, 3, 4 or 5 plants.

It is noticed that the step of packaging the plant 10 may alternative include placing the container 18 in another plant receiving structure such as a pot. It is further noticed that the packaging step may include removing the substrate 18 with the plant 10 from the container 18 and placing said plant holding substrate 18 in another container, e.g., a biodegradable container or a pot.

It is noted herein that a container for plant husbandry, as used herein, is preferably suitable to hold 1-10, preferably 2-5, plants or bulbs of the invention and/or has dimension that do not exceed 50 cm (1) x 50 cm (w) x 20 cm (h), preferably dimensions that do not exceed 30 cm (1) x 30 cm (w) x 20 cm (h), more preferably dimensions that do not exceed 20 cm (1) x 20 cm (w) x 20 cm (h) or 15 cm (1) x 15 cm (w) x 15 cm. A container as recited in the context of the invention is preferably biodegradable. Preferably, dimension are exceeded if at least one value of length, width or height exceeds the indicated value.

The optional step of packaging refers to a step wherein a plant of the invention in container for plant husbandry is placed in a packaging, preferably a paper-based packaging material, for instance a box having a square form. A box of the invention may be square and have the dimensions of about 12 cm (1) x about 14 cm (w) x about 20 cm (h). It is also envisaged herein that the plant is packaged in a foil, preferably a transparent foil, generally used to package plants or flowers.

Preferably, a plant of the invention is individually packaged, so as to provide a package of one frozen, vernalized plant in a container for plant husbandry. It is envisaged herein that two or more of such individually packaged plants are placed in a container or box suitable for holding a multitude of said individually packaged plants. A color code or color corresponding to the color of the flowers of a plant in a container in said packaging may be provided on the container or on the packaging itself.

It is an advantage of the vernalized, frozen plant in a container according to the present invention that it can be sold to the retailer in frozen form. As a result, both the retailer, as well as the household customer can immediately see and feel that these products are of a controlled quality, that is preserved through freezing.

It is an advantage of the vernalized, frozen plant in a container according to the present invention that it provides the retailer with a selling period that is as long as possible, or at least extended as compared to the short selling period of a fresh unfrozen product.

It is an advantage of the vernalized, frozen plant in a container according to the present invention that varieties can now be used that are much lower in price. In principle, such varieties as used for ice tulips in the production of cut flowers may be used. The result is that the relatively less expensive ice tulips or forcing tulips, can now be upgraded to be used as garden tulips.

The plant of the present invention is a frozen potted plant. The plant of the present invention is not a cut flower in the sense that the term is used in the art, although it will be appreciated that once the plant of the invention is outplanted in, e.g., a household garden, the resulting stem and flower can be cut to be displayed elsewhere.

The invention is not restricted to the embodiments described herein. It will be understood that many variants are possible.

These and other embodiments will be apparent for the person skilled in the art and are considered to fall within the scope of the invention as defined in the following claims. For the purpose of clarity and a concise description features are described herein as part of the same or separate embodiments. However, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described.

EXAMPLES

Example 1: Producing a vernalized tulip.

Tulip bulbs of the variety “Apricot Beauty” are bought from tulip bulb growers in a post-harvest period and placed in a climate room.

The tulip bulbs in stage G (indicating initiation of the gynoecium as determinable in dissected bulbs) are subjected to a cold-treatment starting at a temperature of 10 °C or 9 °C which slowly drops the temperature of the bulbs towards 10 °C or 9 °C.

After four weeks at a temperature of 9 °C, tulip bulbs are individually planted in biodegradable plant pots formed of coco filled with a potting soil. Cold-treatment at a temperature of 9 °C is resumed until roots are developing from the bulbs.

The temperature in the climate room is slowly brought towards 2 °C. After six weeks at a temperature of 2 °C, the rooted tulip develops a rooting system in the substrate, and at least part of a stem system and is thereafter stored for ten days at temperature of -5 °C so as to arrest development/induce dormancy.

After a period of storage of ten days, the frozen, vernalized tulips are planted in soil in a garden during the spring season. The vernalized tulips quickly flower.

Example 2: Producing a vernalized tulip.

Tulip bulbs of the variety “Apricot Beauty'” are bought from tulip bulb growers in a post-harvest period and placed in a climate room.

The tulip bulbs are subjected to a cold-treatment at a temperature of 2 °C.

After five weeks at a temperature of 2 °C, tulip bulbs are individually planted in biodegradable plant pots formed of coco filled with a potting soil, the pots and soil being held at room temperature. While being held at a temperature of 2 °C, the rooted tulip is allowed to develop a rooting system in the substrate, and at least part of a stem system and is thereafter stored for 20 days at temperature of -8 °C so as to arrest development/induce dormancy.

After a period of storage of 20 days, the frozen, vernalized tulips are planted in soil in a garden during the spring season. The vernalized tulips quickly flower.

Example 3: Producing a vernalized strawberry plant.

Strawberry rootstock of the variety “Daroyal” is bought from strawberry growers in a post-harvest period and placed in a climate room.

The strawberry rootstock is planted in a biodegradable plant pot formed of coco filled with a potting soil, and as a whole subjected to a cold-treatment at a temperature of 2 °C for three weeks.

After three weeks of cold-treatment, the strawberry plant has developed a rooting system in the substrate, and at least part of a stem system and is thereafter stored for 30 days at temperature of -7 °C so as to arrest development/induce dormancy.

After a period of storage of 30 days, the frozen, vernalized strawberry plants are planted in soil in a garden during the spring season. The vernalized strawberry plants quickly flower.

Claims (19)

A method for manufacturing a vernalized plant product of a vernalization-requiring plant species, comprising the steps of: a) providing a propagating material of a vernalization-requiring plant species, wherein the propagating material comprises at least one seed, bulb and / or rhizome and wherein the propagating material is not cross-linked; b) developing said propagating material in a generalized rooted plant by carrying out at least the following steps in random order: b1) planting said propagating material in a container comprising a substrate to provide a planted propagating material; b2) allowing the planted propagating material to form a rooted plant comprising a root system in the substrate and at least a portion of a stem system; b3) subjecting said propagating material, said planted propagating material, or said rooted plant to a first cold treatment for vernalization at a temperature of 0-10 ° C, preferably for a period of 5 to 100 days, to provide a rooted rooted plant; c) subjecting said generalized rooted plant to a second cold treatment to prevent development and / or growth of the plant, wherein the second cold treatment takes place at a temperature of -20 to -1 ° C, preferably during a period between 2 and 120 days, in order to provide a frozen, rooted plant; d) optionally storing the frozen, crushed rooted plant of step c) at a temperature below 0 ° C; wherein step b) is arranged to provide a nibbled plant product comprising a frozen nibbled rooted plant suitable for transplanting in the form of 1-20 separable flowering units, and wherein the maximum period during which the frozen nibbled plant is below 0 ° C in steps c ) and d) together do not exceed 120 days. A method according to claim 1, wherein after step c) or d) said said plantized plant is packaged in a package for display and sale of said said plantized plant in frozen condition. The method of claim 1 or 2, wherein the starting material is subjected to a first cold treatment for vernalization prior to planting. Method according to any of claims 1-3, wherein the first and / or second cold treatment take place in a protected environment comprising a controlled temperature. A method according to any one of claims 1-4, wherein the vernalisation-spreading plant is a bulb, preferably a bulb of the Liliaceae family, preferably a tulip. The method of any one of claims 1-5, wherein said container is a biodegradable container, preferably a replanting or transplanting container. A method according to any one of claims 1-6, wherein in step b) a plurality of seeds, bulbs and / or rhizomes are planted in a container, preferably between 1-5 seeds, bulbs and / or rhizomes. The method of any one of claims 1-7, wherein the container is a receiving unit comprising a plurality of container volumes. A method according to any one of claims 1-8, wherein the container is a plant pot, preferably with dimensions of 5-20 (1) x 5-30 (w) cm. A method according to any of claims 1-9, wherein the method further comprises the step of storing said shredded plant product in a retail freezer or in a household freezer and / or the step of replanting or transplanting said shredded plant product , preferably in a garden. A method according to any one of claims 1-10, wherein the maximum period in which the crosslinked material is below 0 ° C in step c) and d) is less than 14 weeks, preferably less than 13 weeks. A generalized plant product obtainable by a method according to any one of claims 1-11. The generalized plant product according to claim 12, wherein the container is for replanting or transplanting. The generalized plant product according to claim 12 or 13, wherein the propagating material for planting for replanting or transplanting is planted in a biodegradable container. The generalized plant product according to any of claims 12-14, wherein the package or container comprises a color or color code to indicate the color or colors of the flowers of the plant. The generalized plant product according to any of claims 12-15, wherein the container comprises a layer of a porous medium covering the substrate. The canned plant product according to any of claims 12-16, comprising a single frozen canned plant or a set of two frozen canned plants, preferably wherein the set of two plants is planted in separate containers or in a single container. A package comprising a generalized plant product according to any one of claims 12-17, preferably wherein said package is for storing frozen products. A refrigerator or freezer comprising the varnished plant product according to any of claims 12-17 or the package according to claim 18.