GB2054525A - Trays for hydroponically grown plants - Google Patents

Abstract

For marketing, plants such as lettuces 9 grown hydroponically in porous inert growing blocks 8 are placed in a spaced-apart array in a tray 1,and filler blocks 10, 11 of similar material are inserted to fill the spaces in the tray around the growing blocks. The blocks are then liberally watered. <IMAGE>

Description

SPECIFICATION Equipment for hydroponically growing plants This invention relates to equipment for growing plants hydroponically and for transporting and marketing such plants.

An increasing proportion of glasshouse lettuces is grown hydroponically. Hydroponics is a system of soil-less culture in which plants are supplied, usually continuously, with a flowing solution of chemical nutrients instead of being grown in conventionally fertilised soil or peat. The advantages of hydroponic culture over traditional soil-culture methods are that plants can grow almost twice as quickly and their quality is both higher and more consistent. Its appeal to the grower is a reduction in operating costs, although the initial capital outlay is higher than for conventional growing.

Hydroponic lettuces are grown in growing blocks (eg. 2.5. cm cubes) made of an absorbent inert material such as a mass of rockwool, which gives the plants anchorage. The plants start off as seedlings which are put into their rockwool blocks and the latter are placed on a supporting surface which is usually covered by a capillary mat of non-woven synthetic fabric constructed to be highly absorbent and capable of lifting water as high as 1 50mm by capillary action. Capillary mats suitable for hydroponics must be free from chemical binders or other potential pollutants and may for example have their fibres anchored to each by localised welds. While the plants are growing, the capillary mat typically rests on a sioping concrete floor in the glasshouse.A header-pipe supplied by a header tank runs along the top of the slope and the nutrient solution is fed from it into the capillary mat at spaced points. The mat becomes saturated with the solution and nutrients are conducted from the mat through the growing blocks to the plant roots. Excess solution emerges from the lower end of the capillary mat into a catchment trough which discharges into a catchment tank. This residual solution is then pumped up to the header tank, which is replenished with nutrients by electronic controllers, and is recirculated.

The capillary mats used are large, about 100 x 4.5 metres, and lettuces are spaced evenly, about 20cm apart. As the plants grow, roots extend from the growing block into the capillary mat. The roots are protected from light, which would damage them, by the growing foilage shading them. When the lettuces are grown, the capillary mats are drawn up by a winch from the floor to the harvesting tables. The lettuces are cut at the stems and packaged. The capillary mats and growing blocks are thrown away.

Similar procedures may be followed to grow other hydroponicfoilage plants.

According to the present invention there is provided equipmentfortransporting and marketing plants grown hydroponically in porous growing blocks set in a spaced apart array comprising a tray and filler and spacer blocks for filling the spaces within the tray between the growing blocks and thereby defining an array of spaced apart positions for the growing blocks.

With-this arrangement, the plants can be grown at their optimum spacing. As they grow, their hydroponic roots extend down through their growing blocks.

When they are ready for market, the nutrient solution is replaced by plain water, growing blocks each carrying a grown plant lifted by hand or mechanically and placed in a spaced array in a tray and the filler blocks are inserted to fill the spaces around the growing blocks. The whole assembly of blocks in the tray is then liberally watered and the plants in their tray are then ready for transport, conveniently in a trolley constructed to carry a stack of such trays vertically spaced apart.

The customer can either purchase the complete set of plants (paying a deposit or rent for the tray, unless the tray is disposable) or select one of the plants pulling it together with its growing block upwards away from the other blocks. This can be done easily and without disturbing the other blocks since the hydroponic roots of the plant are fairly weak and the wet blocks are heavy.

The plants can be kept alive and without further development (e.g. bolting in the case of lettuces) simply by watering the blocks.

Preferably a capillary mat, for example of nonwoven polyester fibres is placed on the supporting surface and the growing blocks carrying their seeds or seedlings placed on it in their spaced-apart positions. By cutting the mat into tray-sized portions, the set of grown plants to fill one tray can be lifted simultaneously. By the time the plants are fully grown, their hydroponic roots will have extended through the growing block into the mat and will thus anchor the block to the mat.

The tray may then have a lower portion forming a drainage compartment and a perforated or mesh support for supporting the tray above the drainage compartment.

Although the capillary mat can be cut into tray-size pieces when the plants are fully grown, it is preferred that the capillary mat is cut up before the start of the growing operation.

The invention will now be further described by way of example with reference to the accompanying drawings, in which: Figure 1 shows part of an exploded view of a tray and associated components for transporting and marketing hydroponically grown lettuces, Figure 2 is a cross-section through the tray shown in Figure 1 in its assembled condition.

Figure 3 is a perspective view of part of a tray showing an arrangement for supporting it in a rack, the contents of the tray being removed for clarity, Figure 4 is a side elevational view of a trolley carrying six of the trays shown in Figures 1 to 3, Figure 5 is an end view of the trolley shown in Figure 4, Figures 6and 7are side end elevational views respectively of another form of trolley for carrying six trays, and Figure 8 is a plan view of an alternate arrangement of filler blocks.

The equipment shown in Figure 1 comprises a tray 1 of injection-moulded or hot-pressed plastics mate rial. The lower part 2 of the tray 1 forms a drainage reservoir above which the peripheral wall 3 of the tray is formed with a ledge 4. The floor of the tray carries a set of spacer pedestals 5 for supporting a stiff gauze 6.

When in position, the gauze 6 forms a support for a capillary mat 7, typically formed from non-woven synthetic filaments. The mat 7 carries a spaced array of rockwool growing blocks 8 each containing a plant 9 such as a lettuce.

The assembly of the capillary mat 7, growing blocks 8 and plants 9 has been formed by covering a gently sloping concrete area with mats 7, placing the growing blocks 8, each supporting a seedling, in their positions on the mats, continuously supplying a nutrient solution to the capillary mats during growth of the plants, flushing out the solution and replacing it with plain waterwhen the plants are ready for sale and picking up the individual capillary mats 7, which by then have their growing blocks 8 adequately secured in position by hydroponic roots of the plants which will have extended through the blocks into the mat.

The capillary mat assembly is then lowered onto the gauze 6 and filler blocks, here in the form of crenellated strips 10 and 11, are inserted between the blocks 8 to fill up the spaces between the blocks 8 to provide a substantially continuous top surface 12 (Figure 2). This surface is then liberally watered to saturate the rockwool blocks and strips 8, 10 and 11 any surplus collecting in the drainage space 13 formed in the bottom of the tray. The trays thus assembled are then readyfortransporttothe point of sale.

As can be seen in Figures 1 and 2, the thickness of the strips 10 and 11 where they cross each other is half the height of the block 8. Elsewhere, the strips 10 and 11 have a thickness equal to the height of the blocks 8.

As shown in Figure 3, the upper edges of two of the longer side wall portions of each tray may be reinforced and formed with a downwardly curved lip 16 to enable the tray to be supported on rods 17.

Further, the bottom of the tray 1 may be formed with one or more longitudinal grooves 18 to seat on a further bar or bars 19 parallel to but below the bars 17.

With this arrangement, the trays 1 can readily be mounted on a trolley, such as that shown in Figures 4 and 5.

The trolley shown in Figures 4 and 5 has a post 21 at each end supported at its lower end on the cross beam 22 carrying ground-engaging wheels 23. One or more of the wheels 23 may be fitted with a foot-operated brake 24.

Each post 21 carries three double armed brackets 25 which support the bars 17 and 19 from below so that the trays 1 can be slid into position on the trolley along the bars from one end, the brake 24 being applied. After releasing the brake, the loaded trolley can be wheeled into a van for transport of the point of sale.

At the point of sale, the trays can either remain in position on the trolley or can be arranged as desired.

The continuous top surface 12 gives a pleasant appearance and hides any soiling of the capillary mat 7. It also provides a store of water which slowly drains on to the capillary mat to replace water in the mat absorbed by the plants for transpiration. The customer can either take a complete tray with its contents or can select one of the plants 8 by pulling it upwards. The plant 8 will be relatively firmly anchored to its block 8 while the weight of the saturated filler block strips 10 and 11 will be sufficient to hold the mat 7 in position so that the hydroponic roots of the selected plant are broken at the junction between the block 8 and the mat 7. The purchaser can then insert the plant and its growing block into a polythene bag which may be available from a dispenser (not shown) on the trolley.The plant may be kept alive by the customer for some time simply by keeping the growing block wet.

After sale of the plants in a tray, the tray with its guaze 6 mat 7 and rockwool blocks 10 and 11 is returned to the grower who discards the mat 7 and block strips 10 and 11 and replaces them with new material to reduce the risk of infecting the new crop.

The trolley shown in Figures 6 and 7 has a frame 30 supported on wheels 23, some of which have brakes 24. The trays 1 are supported on rods 17 and 19 as in the trolley shown in Figures 4 and 5. The rods 17 and 19 for each tray are fixed in end brackets 31. The rods 19 at one end (left in Figure 6) are extended and pivoted in the ends of the arms 32 of a spider 33 mounted at its centre for rotation on a stub shaft 34.

At the other end of the trolley, the rod 17a for each tray which is nearer the viewer in Figure 6, and thus each right hand rod in Figure 7, is pivoted in respective arms 35 of a second spider 37 identical to the spider 33 and mounted for rotation on a second stub shaft 36, the axis of which is offset by the same distance and in the same direction as the separation between the rods 17a and 19 for any one tray.

With this arrangement, the trays 1 can be moved around on the 'paternoster' principle while remaining horizontal. Thus the shoper can examine all the plants and having selected a plant can pull it up of its tray and place it in a polythene bag torn from a dispenser 38 carried by the frame 30. Either or both stub shafts 34,37 may include a ratchet or brake, if necessary, to prevent the more completely full trays moving to the bottom.

Figure 8 shows an alternative arrangement of filler blocks short blocks 110 are placed in rows in line with the growing blocks 108 and long blocks 111 fill the spaces between the rows.

In a simplified form of tray, the drainage compartment may be omitted and the gauze repiaced by drainage holes in the bottom of the tray. The trays may be supported in a vertical array in a frame so that the upper trays drain onto the lower trays, a suitable receptacle being placed beneath the lowermost tray.

Claims (6)

1. Equipment for transporting and marketing plants grow hydroponically in porous growing blocks set in a spaced-apart array, comprising a tray and filler and spacer blocks for filling the spaces with in the tray between the growing blocks and thereby defining an array of spaced-apart positions for the growing blocks.

2. Equipment according to claim 1, wherein the tray has a perforated support surface for the blocks.

3. Equipment according to claim 2, wherein the perforated support serves to support a section of capillary mat carrying the growing blocks.

4. Equipment according to claim 3 wherein the perforated support extends over and above a drainage space in the lower part of the tray.

5. Equipment according to any of the preceding claim, comprising a trolley carrying a plurality of the said trays.

6. Equipment according to claim 5, wherein the trolley comprises a conveyor system whereby the trays may be advanced upwards to bring successive trays into a point-of-sale position.