GB1572701A

GB1572701A - Apparatus for growing plants

Info

Publication number: GB1572701A
Application number: GB5113076A
Authority: GB
Original assignee: GARDENAIR NATURAL PLANT DECOR
Current assignee: GARDENAIR NATURAL PLANT DECOR
Priority date: 1976-12-08
Filing date: 1976-12-08
Publication date: 1980-07-30
Also published as: AU3114577A; AU516690B2; NZ185843A

Description

(54) IMPROVEMENTS RELATING TO APPARATUS FOR GROWING PLANTS (71) We, Gardenair Natural Plant Decor Limited, of 28, Bonville Road, Brislington, Bristol, BS4 5QH, a British Company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to self-watering apparatus for growing plants. There have been many prior proposals for controlling the supply of water from a reservoir to a flower pot or similar plant container, but most existing containers of this type suffer from various disadvantages in manufacture or use. In some the flow rate is badly controlled and may become excessive, or may be cut off completely. In others it is difficult to replace or repair any components which are damaged or soiled after a period of use.Also, the aesthetic appearance of many such containers is not very attractive.

Now broadly stated the invention consists in a self-watering apparatus for growing plants, comprising a vessel to hold the soil or humus, a separate water container or cavity communicating with the vessel and a rigid porous control element housed in a separate relatively flexible mounting which is located in a corresponding socket or seating in the base of the vessel, the mounting element being formed with a peripheral lip having a cut-away or notch to permit air trapped below the porous element to escape and so prevent an air lock.

Preferably the porous element is ceramic or of some other brittle material and the mounting is of a relatively soft synthetic plastics material. The mounting is preferably located in the socket or seating by means of a sealing or adhesive material.

The invention may be performed in various ways and one specific embodiment will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic sectional side elevation through a self-watering plant container according to the invention, Figure 2 is a sectional side elevation on an enlarged scale through one of the porous ceramic control elements, and Figure 3 is an underneath plan view of the element of Figure 2.

Referring first to Figure 1, the article comprises an outer cylindrical water container body 10 formed, for example, of a synthetic plastics material reinforced with glass fibres and comprising a base with a surrounding side wall, and an inner cylindrical vessel 11 for the soil or humus, formed of the same material and having a sidewall of somewhat smaller diameter, with a lip or rim 12 around its periphery which overhangs and is rigidly connected to the upper edge of the outer wall 10. The base 13 of the inner body is spaced above the base 14 of the outer member, and their two side walls are also spaced apart, and the two mouldings define between them a water reservoir cavity which includes an annular chamber 15 between the side walls, and a lower chamber 16 between the two bottom walls. To fill the container a removable plug 17 is provided in an aperture in the rim 12.

In the bottom wall 13 of the inner body there are provided one or more rigid porous ceramic control elements, as illustrated in more detail in Figures 2 and 3. Each element includes a small cylindrical disc 20 of a brittle porous ceramic material tightly inset into a relatively soft and resilient synthetic plastics mounting 21, which includes a cylindrical side wall, an upper flange 22, and a small inturned flange or lip 23 around its lower edge. This bottom lip 23 is provided with a small notch 24 for a purpose to be described.

In constructing the whole unit, each of these porous control elements is located in the bottom wall 13 by pressing the plastics mounting into a corresponding aperture, the top flange 22 being sealed and, if required, bonded to the wall 13 by means of a sealing or bonding agent. This arrangement provides an excellent water-tight mounting to prevent any water flowing from the reservoir into the inner container except through the actual porous body of the disc 20. Since the plastics element 21 is of- a softer more flexible material than the container bodies, for example low density polythene with a melt/flow index of 2/4, the ceramic plug can be inserted as a tight press fit into the cylindrical wall 21. The plastics mounting can itself be bonded very effectively to the bottom wall 13 through its surrounding flange 22.The under surface of the ceramic plug is substantially horizontal and the notch 24 is useful in allowing any trapped air below the plug to escape when the water reservoir is first filled. Without this notch a thin layer of air may be trapped below the plug.

One of the advantages of this construction is that any adhesive or sealing substance is located between the plastics mounting and the base wall of the soil container and does not contact the ceramic directly. The adhesive, therefore, does not penetrate into and clog the pores of the ceramic. An effective seal is achieved by making the ceramic a tight press fit in the resilient plastics. By choice of a non-hardening adhesive or sealing material it is possible to remove and replace each unit without difficulty.

It is important that the flow of water through the porous elements 20 should not be impeded by air bubbles or pockets trapped below the water surface. The notch 24 in the lip 23 of the plastics mounting is useful in allowing small air bubbles below the porous element 20 to escape. A problem can arise, however, if the base 13 of the inner container is large and especially if it has an uneven but generally level undersurface. Quite large bubbles or volumes of air may be trapped below this surface, and this can completely block the flow of water through the porous elements. Accordingly, it is desirable that the lower surface 13 of the inner container should be upwardly inclined or domed, as shown in Figure 1, or formed with upwardly inclined air escape channels or grooves.

The composition and characteristics of the porous control elements can be critical.

They must pass an adequate water flow for proper plant growth, but should not pass excessive quantitites. If the soil or potting compound is flooded in water, the plants may be drowned and in any case the water reservoir will be rapidly spent.

The preferred porous material is a refractory ceramic fired at normal porcelain firing temperature, the porosity of the elements (measured as a percentage of the unimpeded flow through an aperture of the same cross-section) is approximately 16% to 17%, or in some cases within the range of 15% to 18%, or more generally between 12% and 23%. The density of the material in its porous condition is preferably of the order of 2.1 to 2.3 gm/ml, or more generally in the range 2.0 to 2.4 gm/ml.

The permeability of such porous control elements can be calibrated in relation to the cross-sectional area and the pressure head and is measured in terms of the volumetric flow rate per unit time.

In the preferred embodiments of the invention the control elements are circular ceramic discs with a diameter of 22 mm, a cross-sectional area of 3.8 cm2, and a depth of 6 mm. It is found that the flow rate through the disc is proportional to the head of water. At a head of about 20 cm. which is normal for a plant container, the flow rate is normally about 6.0 mShr. More generally the flow rate at this head should be within the range of 4 to 8 ml/hr, or approximately 1-2 ml/hr per square cm. of the element.

More than one porous element should be fitted if the area of the inner container exceeds about 200 cm2, and pro rata.

In actual use the complete container will normally be mounted within a separate external decorative container or box 28 of timber or other material providing an attractive external appearance.

WHAT WE CLAIM IS: 1. A self-watering apparatus for growing plants, comprising a vessel to hold the soil or humus, a separate water container or cavity communicating with the vessel and a rigid porous control element housed in a separate relatively flexible mounting which is located in a corresponding socket or seating in the base of the vessel, the mounting element being formed with a peripheral lip having a cut-way or notch to permit air trapped below the porous element to escape and so prevent an air lock.

2. A self-watering apparatus according to claim 1, in which the porous element is of a brittle ceramic material.

3. A self-watering apparatus according to claim 1 or claim 2, in which the mounting is of a relatively soft synthetic plastics material.

4. A self-watering apparatus according to any of the preceding claims, in which the mounting is located in the socket or seating by means of a sealing or adhesive material.

5. A self-watering apparatus according to any of the preceding claims, in which the lower surface of the porous element is substantially horizontal.

6. A self-watering apparatus according to any of the preceding claims, in which the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. the bottom wall 13 by pressing the plastics mounting into a corresponding aperture, the top flange 22 being sealed and, if required, bonded to the wall 13 by means of a sealing or bonding agent. This arrangement provides an excellent water-tight mounting to prevent any water flowing from the reservoir into the inner container except through the actual porous body of the disc 20. Since the plastics element 21 is of- a softer more flexible material than the container bodies, for example low density polythene with a melt/flow index of 2/4, the ceramic plug can be inserted as a tight press fit into the cylindrical wall 21. The plastics mounting can itself be bonded very effectively to the bottom wall 13 through its surrounding flange 22.The under surface of the ceramic plug is substantially horizontal and the notch 24 is useful in allowing any trapped air below the plug to escape when the water reservoir is first filled. Without this notch a thin layer of air may be trapped below the plug. One of the advantages of this construction is that any adhesive or sealing substance is located between the plastics mounting and the base wall of the soil container and does not contact the ceramic directly. The adhesive, therefore, does not penetrate into and clog the pores of the ceramic. An effective seal is achieved by making the ceramic a tight press fit in the resilient plastics. By choice of a non-hardening adhesive or sealing material it is possible to remove and replace each unit without difficulty. It is important that the flow of water through the porous elements 20 should not be impeded by air bubbles or pockets trapped below the water surface. The notch 24 in the lip 23 of the plastics mounting is useful in allowing small air bubbles below the porous element 20 to escape. A problem can arise, however, if the base 13 of the inner container is large and especially if it has an uneven but generally level undersurface. Quite large bubbles or volumes of air may be trapped below this surface, and this can completely block the flow of water through the porous elements. Accordingly, it is desirable that the lower surface 13 of the inner container should be upwardly inclined or domed, as shown in Figure 1, or formed with upwardly inclined air escape channels or grooves. The composition and characteristics of the porous control elements can be critical. They must pass an adequate water flow for proper plant growth, but should not pass excessive quantitites. If the soil or potting compound is flooded in water, the plants may be drowned and in any case the water reservoir will be rapidly spent. The preferred porous material is a refractory ceramic fired at normal porcelain firing temperature, the porosity of the elements (measured as a percentage of the unimpeded flow through an aperture of the same cross-section) is approximately 16% to 17%, or in some cases within the range of 15% to 18%, or more generally between 12% and 23%. The density of the material in its porous condition is preferably of the order of 2.1 to 2.3 gm/ml, or more generally in the range 2.0 to 2.4 gm/ml. The permeability of such porous control elements can be calibrated in relation to the cross-sectional area and the pressure head and is measured in terms of the volumetric flow rate per unit time. In the preferred embodiments of the invention the control elements are circular ceramic discs with a diameter of 22 mm, a cross-sectional area of 3.8 cm2, and a depth of 6 mm. It is found that the flow rate through the disc is proportional to the head of water. At a head of about 20 cm. which is normal for a plant container, the flow rate is normally about 6.0 mShr. More generally the flow rate at this head should be within the range of 4 to 8 ml/hr, or approximately 1-2 ml/hr per square cm. of the element. More than one porous element should be fitted if the area of the inner container exceeds about 200 cm2, and pro rata. In actual use the complete container will normally be mounted within a separate external decorative container or box 28 of timber or other material providing an attractive external appearance. WHAT WE CLAIM IS:

1. A self-watering apparatus for growing plants, comprising a vessel to hold the soil or humus, a separate water container or cavity communicating with the vessel and a rigid porous control element housed in a separate relatively flexible mounting which is located in a corresponding socket or seating in the base of the vessel, the mounting element being formed with a peripheral lip having a cut-way or notch to permit air trapped below the porous element to escape and so prevent an air lock.

base of the vessel is inclined upwards from the centre towards the edges, or formed with upwardly inclined air escape grooves.

7. A self-watering apparatus according to any of the preceding claims, in which the porous element has a porosity in the range between 15% and 18%.

8. A self-watering apparatus according to any of the preceding claims, in which the porous element has a density between 2.0 and 2.4 gm/ml.

9. A self-watering apparatus according to any of the preceding claims, in which the permeability of the porous element, measured at a head of about 20 cm, is in the range of 1 to 2 ml/hr/cm2.

10. A self-watering apparatus according to any of the preceding claims, in which the vessel for the soil or humus is located at least partly inside the water container so as to define a space between the two to act as a water reservoir, and in which the communication between the water container and the vessel is located in the base of the vessel.

11. A self-watering apparatus according to claim 10, in which the vessel for the soil or humus has a side wall and a base and the water container also has a side wall and base, both spaced respectively from the side wall and base of the inner vessel.

12. A self-watering apparatus for growing plants substantially in any of the forms described with reference to the accompanying drawings.