WO1989000377A1

WO1989000377A1 - Improvements in or relating to plant growing methods

Info

Publication number: WO1989000377A1
Application number: PCT/GB1988/000559
Authority: WO
Inventors: George Howard Evans
Original assignee: George Howard Evans
Priority date: 1987-07-09
Filing date: 1988-07-11
Publication date: 1989-01-26
Also published as: AU2087488A

Abstract

The invention relates to a plant growing method wherein each plant is grown, from seed or from a transplanting stage, in a growing unit individual thereto. Each plant growing unit provides a constant volume reservoir in the lower regions of the growing medium (11) for the plant whereby hydroponic liquid supplied to the upper regions of the growing medium flows down to the reservoir and displaces spent liquid from the lower regions of the reservoir. The growing units are supported by strings (25, 32, 43) from an overhead support member (19, 41) and the lengths of the strings can be adjusted so that all the plants can have their growing tips in a common plane. Further, the spacings between plants can be altered to give each plant the room it needs for its next stage of growth whilst affording maximum utilization of the growing enclosure.

Description

"IMPROVEMENTS IN OR RELATING TO PLANT GROWING METHODS

This invention relates co plant growing methods and has particular application to intensive plant growing methods practised within artificial environments.

It is well known in the art to germinate seeds in a special growing medium in a common tray and to transplant the seeds when they have reached a suitable stage of growth by breaking up the growing medium to separate the seedlings. Seedlings raised by such propagation are normally transplanted directly into the ground.

It is also well known in the art to grow seedlings in individual pots or blocks of inert material, supplied with so called hydroponic liquid feed and to transplant said seedlings by simply placing the seedlings onto or into inert material and supplying the plant with hydroponic liquid feed throughout its life.

Both the above methods suffer from the disadvantage that the seedlings must be transplanted into their final locations to afford each plant sufficient room to grow to maturity, which is a great waste of ground area particularly when the plants are in a controlled environmental structure such as a greenhouse.

Throughout this specification the terms "upper" and "lower" used in relation to a growing unit will refer to the unit in its plant-growing disposition.

So-called hydroponic cultivation of plants to maturity is generally practised by one of two methods.

(1) The plants are grown on self- supporting slabs of inert material, such as rockwool, resting on sheets of plastics material, there being a plurality of slabs arranged end to end to form a row with a plurality of rows in parallel array on continuous floor covering sheets of plastics material. The hydroponic liquid is supplied to the upper regions of each slab, adjacent each growing plant, and the hydroponic liquid drains down through the block and runs over the plastics sheeting to drain to earth, or into channels which carry the hydroponic liquid to drain,

(2) the plants are grown on an inert material, often granular material, in trays or trougjhs and the hydroponic liquid is periodically supplied to the trays or troughs to increase the depth of liquid, thereby to feed the plant roots, and after each "feeding" period the trays or troughs are drained of hydroponic liquid.

A major disadvantage of both the above systems is that the plants can be interconnected through the hydroponic liquid and are therefore susceptible to water borne infections. This problem is particularly acute when the slab method is used when the wetted plastics sheeting can provide an interconnecting path for water borne diseases to reach all the plants in the controlled environment building.

A further disadvantage of the above recited methods resides in the waste of hydroponic liquid. In the "slab" method the hydroponic liquid supplied to the upper surface of the slab soaks through the slab, only a small part of the liquid will be brought into intimate contact with the plant roots and the residence time of the hydroponic liquid in the slab is relatively short. In the tray or trough method, once again, the actual volume of hydroponic liquid which contacts the plant roots is only a small part of the volume required to charge the tray.

In general,to avoid infection problems, the hydroponic liquid exhausts to a drain and is not recycled. Some proposals have been made for sterilizing used hydroponic liquid, adding chemicals to the sterilized liquid to make up the nutrient loss and recycling the liquid but such proposals are notused extensively by commercial growers.

The present invention seeks to provide a plant growing method which is economical in growing medium usage and hydroponic liquid usage and which affords optimum growing conditions for the plants grown thereby.

According to the present invention there is provided a plant growing method, wherein a plant is grown from a growing unit containing a volume of growing medium and hydroponic liquid is supplied to the upper regions of said growing medium, characterised by the steps of maintaining a reservoir of substantially constant volume individual to the plant in the lower regions of said growing medium by allowing hydroponic liquid to flow out of the reservoir only from the lowermost regions of said reservoir and causing said hydroponic liquid from the reservoir to flow upwardly to an outlet from the growing unit.

Preferably the method includes the step of lowering the height of the said outlet above the lowermost regions of the growing medium at least once during the life cycle of the plant.

Preferably the method includes the steps of arranging the outlet at such a height above ground level that hydroponic liquid draining from the outlet falls as a discontinuous stream.

Thus, by the method proposed by the present invention a plant growing in the growing medium can have its lower roots continuously immersed in the reservoir of hydroponic liquid and its upper roots periodically washed by hydroponic liquid and periodically exposed to atmosphere, providing the ideal conditions for plant growth, throughout the life of the plant.

Further, by establishing the reservoir within the growing medium, the hydroponic liquid residence time in the growing medium is increased and as the reservoir receives fresh hydroponic liquid to its upper regions and drains spent liquid from its lowest regions the nutrient content of the liquid in the reservoir can be maintained at a beneficial level.

Preferably the method includes the step of suspending a plurality of growing units from a common elongate support element.

Preferably the method includes the steps of arranging the common elongate support element to extend substantially horizontally above the growing units and suspending said growing units in spaced apart relationship along said common elongate support element.

Preferably the method includes the steps of arranging said growing units to be displaceable in the length direction of the common elongate support element, and periodically adjusting the spacing between said growing units to afford each plant sufficient room for its next stage of growth.

Preferably the method includes the steps of suspending each growing unit from the common elongate support element by a suspension means individual thereto and periodically adjusting said suspension means so that all the plants, or adjacent groups of plants, have their growing tips in a common substantially horizontal plane. Preferably the method includes the steps of supporting growing units containing plants of different maturity on the common support element.

Preferably the method includes the steps of arranging a plurality of common elongate support elements in a substantially horizontal plane.

Preferably the method includes the steps of arranging said common elongate support elements to be relatively displaceable in directions at right angles to their elongate directions whilst remaining in said common substantially horizontal plane.

The invention also envisages apparatus for practising the proposed method and according to this aspect of the invention there is provided a plant growing unit comprising a volume of growing medium and means for retaining a substantially constant reservoir of hydroponic liquid in the lower regions of the said growing medium.

Preferably the growing medium is contained in a water impervious sleeve within a container and the axis of the sleeve is substantially vertical when the growing unit is in use.

Preferably the container includes an outlet spaced above the bottom of the container and intended to be spaced above the lower regions of said sleeve when the growing unit is in use.

In an alternative embodiment the plant growing unit comprises a water impervious flexible tube with one end region turned back and secured at its side edge regions to the side edge regions of the mid-length regions of the main body of the tube, growing medium is contained in the main body of the tube and means are provided at the other end of the tube for suspending the tube.

It will be appreciated with the plant growing method proposed above the youngest plants, which may be germinating seed or seedlings, can have the highest position in the controlled environment where, in a temperature controlled environment, the air is warmest and the seedlings/transplants are exposed to uninterupped light, affording the most ideal conditions for the seed and the initial growth stages of the seedlings.

Between the highest plants (the seed or seedlings) and the most mature plants at or near ground level, there may be any number of intermediate plants, depending upon the height of the plants being cultivated.

Because the plants can be "stacked" in a decending order of maturity, and thereby of foliage growth, the plants at each level are not unduly shadowed by the plants thereabove.

The means for suspending the growing units from the elongate support elements may conveniently comprise wires, string or cords, hereinafter referred to as strings, attached to the overhead elements whereby two great advantages are obtained;

(1) the foliage of each plant can attach to and be supported by its respective supporting string and

(2) the string can be lengthened from the top as the plant grows, without disturbing the support afforded to the foliage by the string.

In one embodiment in accordance with the invention a plurality of plants are suspended in rows with their respective upper regions in a substantially common horizontal plane so that their respective growing points are all exposed to the light. This is readily achieved by adjusting the length of the respective strings whereupon mature plants can grow side by side with less mature plants and the "height" of each plant is downwardly from the plane of the growing points

The invention will now be described further by way of example with reference to the accompanying drawings in which;

Fig. 1 shows, diagrammatically and in cross section, one growing unit in accordance with the invention, Fig. 2 shows, diagrammatically and in perspective view, a second embodiment in accordance with the invention,

Fig. 3 shows, diagrammatically and in perspective view, a second growing unit embodiment in accordance with the invention,

Fig. A shows a front view of a growing system in accordance with the invention.

In the simple embodiment illustrated in Fig. 1 a block 11 of an inert material, such as rockwool, has a water impervious water membrane 12 defining side walls extending from its upper to its lower regions. The block 11 is inserted into a snug fitting container 13 of a water impervious material, such as a plastics material.

The container 13 has a slot 14 therethrough, at a predetermined height above the base of the block 11,and a small part of the impervious layer 12 may be broken away or notched at its lower regions as at 15. The assembly 11 to 15 constitutes a "growing unit" in accordance with the invention.

When the growing unit is in use hydroponic liquid is supplied to the upper regions of the growing medium via a conduit 16 supported by a spike 17. When a plant P is grown from seed in the growing medium 11, or is transplanted into the growing medium 11, and is intermittently supplied with hydroponic liquid, via conduit 16, the hydroponic liquid is deposited onto the top surface of the block 11 and flows downwardly through the block 11 to and past the upper roots of the plant and downwardly to the lower regions of the rockwool block 11. The liquid accumulates in the lower region of the block 11 and seeps through the notch 15 into the container 13.

As the level of liquid rises in the block 11, forming a reservoir within block 11, the level of the liquid between the membrane 12 and the walls of the container 13 rises until the container liquid level reaches the slot 14. Thereafter, as additional liquid is released from conduit 16 into the block 11 and drains down to join the reservoir, liquid between the membrane 12 and the container spills from the slot 14 maintaining the reservoir at the level pre-determined by the height of the slot 14 above the base of the container 13.

The container 13 may be interchangeable with other containers 13 having their respective slots 14 at different heights so that the block 11 may initially be supported in a container 13 with a relatively high slot 14, to maintain a relatively large reservoir accessible to the roots of small plants, and subsequently moved into another container with a lower slot 14 as the plant grows and the root structure reaches downwardly into the growing medium 11.

The container 13 illustrated in Fig. 1 is of a rigid construction and includes a rigid hook 18 by which the growing unit may be suspended on a common elongate supporot element, such as a horizontal rail or tensioned cable 19, whereby the growing unit is out of contact with the ground and the hydroponic liquid overflowing from the slot 14 is released as droplets so that there is no continuous liquid path along which water borne diseases can pass to the plant.

In the embodiment shown in Fig. 2, the growing medium 21, contained by an impervious membrane 22 (shown in broken lines), is supported in a container, conveniently a plastics bag 23. Hydroponic liquid is supplied to the growing medium by a conduit and spike (not shown) in identical manner to the Fig. 1 embodiment.

The plastics bag 23 receives the growing medium package 21, 22 snugly therein and has a slot 24 above the bottom of the bag and which determines the height of the hydroponic liquid reservoir within the growing medium 21.

The bag 23 includes two holes 23a, 23b in its upper regions, spaced apart around the circumference of the bag neck, and whereby the bag 23, with the growing medium therein and a plant P growing from the growing medium 21, may be hung from a string or cord 25 to be clear of the ground.

With this embodiment the slot 24 may be relatively high when the plant is small and further slots 24 may be cut in the bag 23 as the plant grows to reduce the height of the reservoir in the growing medium 21.

The horizontal cross section of the volume of growing medium 11 in the Fig. 1 embodiment or 21 in the Fig. 2 embodiment may be of any desired cross section and the growing medium may be of any desired inert material, including granular materials, and the water impervious side walls 12 or 22 may comprise so-called "shrink wrap" plastics material.

In the example illustrated in Fig. 3 a length of tubing 31, which may be of rubber, plastics material or any other inert water-impervious flexible sheet material, has one end 31a cut square to the axis of the tube and its other end 31b cut at an angle to the direction of the tube axis.

The end 31a is turned back on the tube body by heat welding and secured to the tube body by welding the side corners of end 31a, to the tube body or by fixing said side corners with an adhesive, care being taken not to close the bore opening in end 31a.

The end 31b has an aperture 31c therethrough and by which the body 31 may be suspended by a cord 32.

In use the body 31 of the tubing is packed with an inert material 33, such as a granular material, a seedling P is transplanted into the upper regions of the inert material and the inert material is periodically supplied with hydroponic liquid via a conduit 16 in identical manner to the Figs. 1 and 2 embodiments.

The hydroponic liquid supplied to the upper regions of the inert growing medium drains through the inert material, effectively washing the upper plant roots in hydroponic liquid, and into a reservoir in the lower regions of the inert material. As the level of the reservoir rises liquid is forced from the lower regions of the reservoir and rises up to the open end 31a from which it drips to the ground as a discontinuous stream. Thus, as with the Figs. 1 and 2 embodiments, the level of the outlet of end 31a determines the level of the reservoir within the inert material.

If during the life of the plant it is required to lower the level of the reservoir it is only necessary to cut a horizontal slot in the outwardly facing wall of end 31a and that slot will then become the outlet for the hydroponic liquid.

In the embodiment illustrated in Fig. 4 a common elongate support element 41, which may comprise a rigid rail or a flexible tensioned member, 41 extends across an enclosed growing environment, such as a greenhouse, or in the length direction of the enclosure and in the upper regions of the enclosure and growing units 42, are suspended from the element 41 by strings 43.

The broken line 44 identifies a horizontal plane intended to be a growing plane for all the plants supported from the element 41.

In practise, a seedling in its growing unit 42 is supported from the element 41 so that the growing point of the plant lies in or adjacent the growing plane 44. As the plant grows the string 43 supporting the growing unit 42 is lengthened so that the growing point remains in or approximately in the plane 44.

This lowering of the growing unit 42 to maintain the growing tip of the plant in the growing plane 44 is continued until the plant is matura, at which stage the growing unit 42 will be close to the base or floor of the enclosure.

It will now be seen that with this arrangement the element 41 can support a plurality of mature plants together with a plurality of plants in different stages of maturity, all the plants have their growing points in the growing plane 44 and the spacing of the strings 43 on the tension member 31 can be so adjusted that each plant has exactly the amount of spacing it requires for its current stage of growth, whereupon maximum utility of the volume of the growing environment can be achieved in the length direction of the element 41.

Within the controlled environment (the greenhouse) there may be a plurality of elements 41 in side by side relationship, each supporting a plurality of growing units 42, and the elements 41 may be displaceable in their horizontal plane at rigjht angles to their length direction so that maximum utilization of the space between adjacent tension members 41 can be achieved whilst, at the same time, a passage can be made through the greenhouse through any pair of tension members 41 to allow cropping of the mature plants.

Whilst the present invention has been described by way of example with reference to two specific embodiments the invention is not restricted thereto and many modifications and variations will be apparent to persons skilled in the art

Further, as the plants are individually potted their spacings apart may be varied and adjusted to their immediate needs so that better utilization can be made of the growing enclosure.

Further, as the growing units can be supported above the ground they are individually protected against continuous water paths and thereby against water borne infections, except for such infections as may be introduced in the hydroponic feed liquid.

Claims

1. A plant growing method, wherein a plant is grown from a growing unit containing a volume of growing medium and hydroponic liquid is periodically supplied to the upper regions of said growing medium, characterised by the steps of maintaining a reservoir of substantially constant volume individual to the plant in the lower regions of said growing medium by allowing hydroponic liquid to flow out of the reservoir only from the lowermost regions of said reservoir and causing said hydroponic liquid from the reservoir to flow upwardly to an outlet from the growing unit.

2. A method as claimed in claim 1 characterized by the step of lowering the height of the said outlet above the lowermost regions of the growing medium at least once during the life cycle of the plant.

3 A method as claimed in claim 1 or 2 characterized by the steps of arranging the outlet at such a height above ground level that hydroponic liquid draining from the outlet falls as a discontinuous stream.

4. A method as claimed in claim 1, 2 or 3 characterized by the step of suspending a plurality of growing units from a common elongate support element.

5. A method as claimed in Claim 4 characterized by the steps of arranging the common elongate support element to extend substantially horizontally above the growing units and suspending said growing units in spaced apart relationship along said common elongate support element.

6. A method as claimed in Claim 5 characterized by the steps of arranging said growing units to be displaceable in the length direction of the common elongate support element, and periodically adjusting the spacing between said growing units to afford each plant sufficient room for its next stage of growth.

7. A method as claimed in Claims 4, 5 or 6 characterized by the steps of suspending each growing unit from the common elongate support element by a suspension means individual thereto and periodically adjusting said suspension means so that all the plants, or adjacent groups of plants, have their growing tips in a common substantially horizontal plane.

8. A method as claimed in Claims 4, 5, 6 or 7 characterized by the steps of supporting growing units containing plants of different maturity on the common support element.

9. A method as claimed in claims 4, 5, 6, 7 or 8 characterized by the steps of arranging a plurality of common elongate support elements in a substantially horizontal plane.

10. A method as claimed in Claim 9 characterized by the steps of arranging said common elongate support elements to be relatively displaceable in directions at right angles to their elongate directions whilst remaining in said common substantially horizontal plane.

11. A plant growing unit for practising the methods according to Claims 1 to 10 inclusive and comprising a volume of growing medium and means for retaining a substantially constant reservoir of liquid in the lower regions of said reservoir.

12. A plant growing unit as claimed in Claim 11 characterized in that the growing medium is contained in a water impervious sleeve within a container and the axis of the sleeve is substantially vertical when the growing unit is in use.

13. A plant growing unit as claimed in Claim 12 characterized in that the container includes an outlet spaced above the bottom of the container and intended to be spaced above the lower regions of said sleeve when the growing unit is in use.

14. A plant growing unit is claimed in Claim 11 characterized in that said unit comprises a water impervious flexible tube with one end region turned back and secured at its side edge regions to the side edge regions of the mid-length regions of the main body of the tube, growing medium is contained in the main body of the tube and means are provided at the other end of the tube for suspending the tube.