Improved growth module and methods for growing plants.

Abstract

A hydroponic growing system (20) for growing plants comprises a support structure (2) for propagation material which comprises at least one grow hole (3). The grow hole is a through hole having an upper opening (5) and a lower opening (6), wherein the upper opening is wider than the lower opening. The upper opening is wide enough for receiving propagating material and the lower opening is narrow enough to prevent the propagating material from falling through but wide enough to provide passage to roots (10) of the growing plants. The support structure may comprise a base element (9) and a top element (4) positioned on the base element, wherein the base element and the top element together define a part of the grow hole. Also provided is a method for growing plants, comprising providing plant propagation material in such a growing system and allowing the propagation material to develop into plants, preferably until harvest stage.

Description

[0001]IMPROVED GROWTH MODULE AND METHODS FOR GROWING PLANTS. The present invention relates to a hydroponics growing module for growing plants. It further relates to a method for growing plants. Plants such as fruits and vegetables are traditionally cultured in soil out on the field, or in glasshouses under a controlled environment. More recently, many advancements have been made in the culturing of plants using hydroponics. Hydroponics is a newer form of horticulture involving culturing plants without the use of soil, instead using water-based mineral nutrient solutions. Hydroponics may involve the use of alternative substrates that may range from volcanic glass and gravel, peat substrate mixes to rock wool. Hydroponic culturing offers many advantages over traditional soil-based culturing, such as improved control of disease caused by soil-borne pathogens and a major decrease in water usage. An optimal nutrient composition tailored to specific crops may be introduced in such systems. Additionally, the exposure of the root system of the seedling to air increases the oxygen uptake. However, hydroponics has its own challenges. Alternative means of support need to be provided to the growing plants, and not all means are equally suitable for the different species of plants that may be grown. Like soil, these means may also become contaminated by pathogens and need to be kept sterile. Furthermore, the roots systems of the growing crops can start clogging up the inlet for and / or the flow of the nutrient solution if plants are growing in the system for too long. Hydroponics is therefore primarily used for leafy greens that can be harvested at a relatively young stage such as spinach, lettuce, chards, and rocket, but also for leafy herbs such as basil and parsley. The substrate may then be decontaminated in between the relatively short growth cycles. As the advantages of hydroponic culturing allow for a more efficient growth of crops in a far more controllable environment, hydroponics naturally represents a highly attractive method for growers and is consequently a fast-growing market, growing at 10-15 % annually. In hydroponics, plants are generally cultured in individual containers such as pots or jars, or trays, using a growth plug as substrate. These individual containers are placed in or above a larger container providing the nutrient solution. Seeds or seedlings are placed in or on the substrate present in these containers. After germination and further growth, the growing roots eventually reach the nutrient solution for the take-up of water and nutrients. Well-known techniques for providing water and nutrients include NFT (Nutrient Film Technique), in which a thin layer of nutrient solution is circulated through fluid channels or gutters from which the roots can take up all water and nutrients they require, or DWC (Deep Water Culturing), in which seeds and seedlings are placed in containers on a float, which floats on a large water reservoir. The large reservoir supplies the water and nutrients required by the plants. The problem with some of these systems, especially when growing plants in high densities, is that during growth the gutter fills up with the growth medium and the growing roots. As a result, the water flow becomes blocked towards the end of the growing cycle. This may affect the growth of the plants. In addition, the water content in the growing medium may not be uniformly divided throughout the gutter resulting in less uniformity in plant growth. The growth medium may pollute the growing system and may contaminate the plants with residues of the substrates. Also, phytosanitary contamination risks could occur by using some types of substrates. Finally, nutrients and water need to be in contact with the seed and seedlings. When grown in soil or another (semi)-solid substrate such as rock wool, the seeds are in contact with nutrients and moisture through the substrate in which they are comprised. However, when such a substrate is not used in a hydroponics installation, moisture and nutrients need to be provided to the seeds and seedlings in an alternative way. This problem can be addressed by introducing spray jets for example, but this complicates the installation and makes it more expensive. These issues are addressed in the art by the grow system described in WO 2023 / 148223 A1. Since it is not possible to position seeds or small plants in a gutter without any form of support, WO 2023 / 148223 A1 provides an alternative for the use of containers with a substrate. The system disclosed in WO 2023 / 148223 A1 comprises a gutter with a fluid receptacle and a tape, which tape is fixed in the open top end of the gutter in upright position. The tape forms a platform for the plant propagation material and extends downwards into the nutrient solution, thus wicking up said nutrient solution through capillary action. This way, the tape provides both support and nutrients to the propagation material. The tape consists of two layers held together by glue or stitches, which serve to provide a barrier that stops the seeds from falling through the opening between the layers, while leaving space for initial roots to reach the nutrient solution. The tape and the means for holding the layers together are biodegradable, thus supporting the propagation material initially, and over time breaking down to allow more room for the growing plant and its developing roots. Thus, it provides full support until the roots of the growing plants can reach the nutrient solution by themselves, after which the breakdown starts. However, this system has the drawback that the deterioration of the tape is difficult to control. This can lead to premature destabilization of the platform and may cause the seeds or seedlings to fall through the opening between the layers of the tape (slit) before the root system and leaves are developed well enough to hold the seedling in place. In extreme cases, one or both of the layers of tape can fall into the gutter entirely if the glue or stitches connecting them degrade too fast. On the other hand, if deterioration does not happen fast enough, the stitches and the glue holding the tape together remain for too long and eventually obstruct further development of the roots. As the deterioration of the tape is not uniform over the length of the gutter, seeds located at spots where the deterioration sets in later will be less developmentally advanced than plants that could grow out their root system earlier. Because harvesting of gutters happens at a set time along the entire gutter, this lack of uniform growth leads to premature harvest of a part of the total plants in the gutter, in addition to another part of the plants not being harvestable because the seeds may have fallen through the slit. In WO 2024 / 178408 A2 a device and method are disclosed for growing plants from seed, seedling, clone, root stock or young plant without the use of synthetic or natural fibers, fibrous media or porous media. The device comprises flexible non- fibrous, non-porous structures that support the seed, clone, plant or root stock during growth, while also establishing a delineation between the root zone and shoot zone of the plant. EP 3308638 A1 discloses a floating support device for hydroponic cultures formed of a panel made of polymeric material comprising a plurality of separate and distinct hollow tubular elements arranged side-by-side and spaced apart in parallel so as to create a plurality of seats suitable to contain an inert substrate for hydroponic cultures, each defined between two adjacent tubular elements and extending between an upper opening and a lower opening. The tubular elements may each have a shaped cross-section, defined by a curved top portion and a pair of flat and inclined side walls extending symmetrically with respect to a vertical axis and diverging towards the outside, such that the seats have a substantially "funnel-shaped" section. JP 2007-151543 A discloses a hydroponic apparatus which is equipped with a trough-like container in which the interior is a flow channel for water or a culture solution and a holding container provided on the upper side of the trough-like container in the longitudinal direction of the trough-like container, forming a two-tank structure and holding plants. The holding container is provided with a container body having a recessed part for holding the plants, hole parts formed in the bottom of the container body as openings for passing roots of the plants downward, a nonwoven fabric which is a holding material provided in the recessed part of the container body for holding seeds or the plants and a draining means for making water or the culture solution sticking to the container body and the holding material flow downward. The draining means is tapered parts formed by tilting the lower part of the container body downward. The lower part of the container body has a cross-section of nearly V-shape. It is an object of the current invention to provide an alternative growth module for hydroponics systems that can deliver a uniform growth result while avoiding the use of common solid substrates. The invention therefore relates to a hydroponic growing system for growing plants, which system comprises a support structure for propagation material which comprises at least one grow hole, which grow hole is a through hole having an upper opening and a lower opening, wherein the upper opening is wider than the lower opening, the upper opening being wide enough for receiving propagating material and the lower opening being narrow enough to prevent the propagating material from falling through but wide enough to provide passage to roots of the growing plants. In this way a tapered or funnel-shaped grow hole or grow space is defined. The support structure may comprise at least one fluid receptacle for receiving a liquid nutrient or water. Suitable nutrient solution or water can be circulated through the fluid receptacle. The dimensions of the receptacle should be such that even after formation of the root system, sufficient nutrient solution can reach all plants in the fluid receptacle. The support structure itself may be made of inert material that can be easily decontaminated and cleaned, such as various polymers and plastics. The propagation material used may comprise, for example, seeds, germinated seeds, seedlings, plantlets, cuttings, etc. These materials can be placed in the grow holes in various stages of development. As they differ in size, the requirements for the dimensions of the lower opening may also differ. These dimensions can be chosen to suit these requirements. The growing system of the invention may be used with seeds or seedlings, more in particular pilled seeds, coated seeds, or other types or pretreated seeds. In one embodiment, the growing system of the invention comprises a base element and a top element positioned on the base element, wherein the base element and the top element together define at least a part of the grow hole. Having the grow hole partially defined by two cooperating elements may increase structural simplicity. To this end the top element and the base element may have mating surfaces or complementary shapes. In a further embodiment, a major part of the grow hole is comprised in the top element and the dimensions of the lower opening of the grow hole are defined by the base element. The base element may define the dimensions of the lower opening in various ways. For example, it may comprise a substrate or protrusion that physically interacts with the lower opening of the grow hole. The base element may physically obstruct or close off part of the lower opening of the grow hole, thereby defining the dimensions of the open section of said lower opening. This may be done by aligning one surface of the base element with a part of the lower opening of the grow hole in the top element while leaving the remaining part open. In one embodiment, the at least one fluid receptacle is positioned along the length of the base element. This may apply in the case of an elongated fluid receptacle, such as a gutter. The base element may be an integral part of the fluid receptacle or can be a separate structure that is placed in or on the fluid receptacle. In another embodiment, the top element may further comprise at least one protrusion and / or recesses in the lower opening of the grow hole. Such protrusions may serve to at least partially obstruct the open section of the lower opening of the seedling hole, thus preventing the seed or propagation material from falling through. On the other hand, the recesses leave additional space for the seed or propagation material to form roots and to allow the roots to grow towards the fluid receptacles. To provide water and nutrients to the growing propagating material, a suitable substrate may be used. This substrate is in contact with the nutrient solution and delivers the solution to the propagating material located at the lower opening of the grow hole in the top element. Therefore, in a further embodiment, a substrate is placed between the top element and the base element, wherein the substrate at least partially covers the lower opening of the hole. The substrate is capable of capillary action to wick up the nutrient solution to the propagating material deposited in the grow holes. In an embodiment, the substrate is biodegradable. Since the top and base elements are made of an inert material and together define the dimensions of the opening, there is no danger of the propagating material falling through prematurely. The seeds are able to attach themselves to the substrate via their roots. This provides the seedlings with improved stability for growth and facilitates the proper development of their root network. Examples of such substrates include, but are not limited to, paper or cloth or composites of such materials. Therefore, in a further embodiment, the substrate is paper or cloth or a composite thereof. The substrate may be placed on a surface of the base element which can conveniently support a substrate. This surface then also defines the dimensions of the open section of the grow hole in the top element. This may be achieved through the physical obstruction or coverage of at least part of the lower opening of the grow hole in the top element by the substrate support surface of the base element. Therefore, in one embodiment, the base element has at least one substrate support surface for supporting the substrate material thereon, and a part of the lower opening of the grow hole is arranged to face the substrate support surface, and wherein the substrate support surface is arranged to cover the facing part of the lower opening of the grow hole, such that an uncovered section of the lower opening of the grow hole is narrow enough to prevent propagation material placed in the grow hole from falling through, but wide enough to provide passage to roots of the growing plants. The substrate support surfaces can be a flat surface on which a suitable substrate may be placed. However, the surface may also have a convex or concave shape. In an embodiment, this substrate support surface is sloped with respect to the horizontal plane of the base. This way, the substrate support surface rises upwards from the bottom of the base element at an angle and provides the propagation material and the top element with an elevated position in respect to the base element itself. The substrate may be placed upon this sloped surface. In a further embodiment, the upward slope of the substrate support surface is between about 45 and 90 degrees with respect to the horizontal plane of the base element. In another embodiment, the base element comprises at least one protrusion which is triangular or trapezoid shaped in cross-section for supporting the top element thereby defining the lower opening of the grow hole. This protrusion comprises the substrate support surface(s). The substrate support surface can be located on either side of the protrusion, or surfaces may be provided on both sides of the protrusion to engage with two grow holes in the top element. In one embodiment, the longitudinal protrusion features only a single substrate support surface and consequently only features a sloped surface on one of its sides. The other side of the protrusion may then have no slope or a different slope as it does not need to support a row of grow holes. This side of the protrusion may then be shaped such as to provide a tighter fit of the top element with the base element, providing additional stability to the growth module. In one embodiment, the base element comprises several longitudinal protrusions. The respective substrate support surfaces are suitably arranged to not obstruct each other. The lower opening of the or each grow hole in the top element is located above the sloped substrate support surface of the protrusion of the base element and is partially obstructed or closed off by that surface. A section of the lower opening of the grow hole is not obstructed by the sloping substrate support surfaces and thus remains open. Through this section, roots may grow downwards along the sloped surface. Depending on the slope of the substrate support surface and on the height of the top part, the open section of the lower opening in the grow hole may be wider or narrower. By choosing these parameters appropriately, the size of the non-obstructed section of the lower opening of the grow hole is narrow enough to block propagation material from falling through, but wide enough to let growing roots through. The protrusion that comprises the substrate support surface may be part of the base element, but may also be a separate, removable element. The base element may comprise one or more of such protrusions comprising the substrate support surfaces. In a further embodiment, the support structure comprises a plurality of grow holes arranged in a pattern. In this way a large number of plants may be grown in a single support structure. Arranging the grow holes in a pattern allows the positions and spacing of the plants to be controlled, which may promote plant growth. In one embodiment, the support structure comprises two longitudinal rows of opposite grow holes, and the juxtaposed grow holes are mirrored. In this embodiment, the substrate support surfaces of the base element are similarly mirrored, and are each located below one of the longitudinal rows of grow holes. The grow holes are not necessarily arranged in two opposite rows and the grow holes are not necessarily juxtaposed or mirrored. The grow holes may be provided in the top element in any desired arrangement as long as they are configured as described herein. In one embodiment, the number of rows of grow holes in a top element matches the number of substrate support surfaces of the base element it engages with. In the embodiment wherein the top element comprises two longitudinal rows of opposite grow holes and wherein the two rows are mirrored over the longitudinal axis, the roots of the germinating seeds and seedlings in the grow holes then grow towards either side of the protrusion and do not interfere with each other, leading to a more optimal usage of space. In another embodiment, the top element comprises a single longitudinal row of grow holes. In this embodiment, the top element may have an inverted L-shape in cross-section, including a substantially horizontal upper part comprising the grow hole and a substantially vertical part extending downwardly therefrom towards the base element. The lower opening of the grow hole(s) may engage with the single substrate support surface of the base element. On the opposite side of the row of grow holes in the top element and the corresponding substrate support surface in the base element, the top element comprises a protrusion, the downwardly extending vertical part, which wraps around the base element, resulting in a half-triangle or half-trapezoid shape. This makes the top element fit the base element more tightly resulting in improved stability. In an embodiment, the top element comprising the grow holes may be removable from the base element and may then constitute a separate element. The bottom of the removable top element may be shaped to fit the protrusion with the substrate support surfaces on the base element, so that at least a section of the lower openings of the one or more grow holes is blocked by the substrate support surfaces. The removable top element allows for a more convenient positioning of a substrate on the one or more substrate support surfaces on the base element, after which the top element can be placed on top thus sandwiching the substrate between the top and base elements. Furthermore, it allows for the placement of a different top element on the same base element, thus allowing the grower to change the fit of the top element on the substrate support surfaces of the base element. By changing the fit, the grower can change the resulting size of the open second section of the hole, which in turn provides a different amount of space for the roots of the propagation material to grow through. For smaller propagation material a smaller open second section may be chosen by using a top element that has a larger contact surface with the base element, while for larger seeds, a larger opening may be left by choosing a top element that has a smaller contact surface with the base element. This allows the grower to use the same base element for different plant species by using a different top element, as the size of seeds is not uniform between plants. This provides the grower with flexibility, saves material and the base element can remain in its position in the structure, i.e. in the fluid receptacle. Alternatively, the size of the seeds may be changed by the grower to instead fit the dimensions of the lower opening of the grow hole such that its passage is obstructed. This can for example be done through pilling the seeds and coating them to have a specific diameter that fits a particular combination of base and top elements. As such, he size of the seed pill may be adapted or selected to have a size such that the seed pill cannot pass through the section of the lower openings of the one or more grow holes that is not blocked by the substrate support surfaces. The invention further relates to a support structure for use in a growing system as described above. And the invention also relates to a method for growing plants, comprising providing plant propagation material in a growing system as described herein and allowing the propagation material to develop into plants, preferably until harvest stage. The invention furthermore relates to a method for growing plants, comprising the steps of a) providing propagation material in a grow hole in a support structure, the upper opening of which grow hole is wide enough for receiving propagating material, and the lower opening of which grow hole is narrow enough to prevent propagating material from falling through but wide enough to provide passage to roots, and b) allowing the propagation material to grow into harvestable plants. The method of the invention may be performed with a wide variety of plants, including but not limited to vegetables, herbs, and sprouts. Hydroponic systems are especially suitable for leafy green vegetables in which the leaves are harvested in a relatively young stage. In an embodiment, the method of the invention is therefore performed for growing lettuce (Lactuca sativa), spinach (Spinacea oleracea), rucola (Eruca vesicaria or Diplotaxis tenuifolia), endive (Cichorium endivia or Cichorium intybus), corn salad (Valeriana locusta), brassica (Brassica oleracea or Brassica juncea or Brassica rapa or Brassica napus or Brassica nigra or Brassica carinata) and / or Swiss chard (Beta vulgaris). The growth system of the invention can be used in different hydroponic setups. In one embodiment, the support structure of the invention is used with utilization of Nutrient Film Technique (NFT). In NFT type hydroponics, a thin, circulating layer of nutrient solution is delivered to the growing plant roots or to the substrate through fluid channels. These fluid channels or receptacles may be connected to or integrally formed with the base element and may extend parallel to the longitudinal protrusion on either side thereof. The support structure may also be used for other types of hydroponic culturing, such as a Deep Water Culture (DWC) system. In such an embodiment, the support structure is arranged to float on the water. It must be designed to provide sufficient flotation, even when the plants are fully grown. If the support structure is made up of a top element and a base element, the base element itself may be a float with a protrusion, on top of which the top element with the seed holes may be placed. Alternatively, a plurality of base elements may be connected to a float. A substrate may optionally be used as well to further facilitate the take up of water and / or nutrients from the large reservoir to the seeds. The support structure may be an elongated structure that can be placed in existing hydroponics gutters but may also have other shapes. The invention will be further illustrated by referring to the following figures: Fig.1 shows a perspective view with parts broken away of one embodiment of a growing system according to the invention. Figs.2A-E show photographs of the system of the invention in use. Fig.3 shows an exploded view of the embodiment of Fig.1. Fig.4A shows a perspective cross section of the embodiment of Fig. 1. Fig.4B shows a detail of the cross section of Fig.4A. Figs.5A-D2 show the top element and base element of various embodiments of the support structure. Figs.6A-C show photographs of a further embodiment of the top and bottom parts. Fig.7 shows a perspective view of the top and base elements of the support structure of Fig. 6. A hydroponic growing system 20 for growing plants 14 comprises a support structure 2 for propagation material, e.g. seedlings 1 or seeds 11. The support structure 2 comprises at least one grow hole 3 - with six grow holes 3 arranged in two rows 14 of three holes 3 each being shown in the embodiment illustrated in Fig.1. Each grow hole 3 is a through hole having an upper opening 5 and a lower opening 6, and each upper opening 5 is wider than the corresponding lower opening 6. The upper opening 5 is wide enough for receiving propagating material, here a seedling 11, and the lower opening 6 is narrow enough to prevent the propagating material from falling through but wide enough to provide passage to roots 10 of the growing plants. In the illustrated embodiment the upper and lower openings 5, 6 are connected by a tapering wall or funnel 25. In the illustrated embodiment, the support structure 2 further comprises a fluid receptacle 13 for receiving a liquid nutrient and / or water 12. Here the fluid receptacle 13 is a gutter, through which a shallow layer of liquid nutrient and / or water 12 is circulated, and in which the support structure 2 is placed. The roots 10 extending through the lower opening 6 come into contact with the liquid nutrient and / or water 12. This type of hydroponic culturing is known as Nutrient Film Technique (NFT). In other embodiments (not shown here) the fluid receptacle may be a basin in which the support structure may float, a so-called Deep Water Culture (DWC) system. In this embodiment, the support structure 2 comprises a base element 9 and a top element 4 which is positioned on top of the base element. Together, the top element 4 and the base element 9 define at least a part of the grow hole 3. As shown here, a major part of the grow hole 3 is comprised in the top element 4, while the dimensions of the lower opening 6 are defined by the base element 9. The lower opening 6 of the grow hole 3 is shown to include a section that is bordered by a lower edge of the funnel 25 and a section 16 that is cut out of funnel 25. This cut-out section 16 of the lower opening 6 faces the base element 9 and is covered or closed off thereby. In this way the base element 9 cooperates with the top element 4 to define the lower part of the grow hole 3. The remaining uncovered section of the lower opening 6, which is in this embodiment is shown to be parallel to the upper opening 5 of the grow hole 3, is narrow enough to prevent the seedling 1 from falling through, but wide enough to provide passage to the roots 10. In the illustrated embodiment, a substrate material 7, e.g. cloth, paper or a composite thereof, is arranged between the top element 4 and the base element 9. Here the substrate material 7 is in contact with the lower opening 6 of the grow hole 3. In fact, the substrate material 7 is supported by a surface 8 of the base element 9 which covers or closes off the cut-out section 16 of the funnel 25, and as such cooperates with the base element 9 in defining the lower part of the grow hole 3 and the dimensions of the lower opening 6. As shown here, the substrate supporting surface 8 of the base element 9 is inclined or slopes with respect to the horizontal, as represented e.g. by a bottom 21 of gutter 13. The angle of inclination or slope angle may be between 45 and 90 degrees, although other angles are conceivable as well. In this embodiment, the top element 4 includes two rows 14 of grow holes 3, and the base element 9 has two sloping substrate support surfaces 8. As the slope angle is the same for both substrate support surfaces 8, here the base element 9 has the shape of an isosceles triangle. The inclined substrate support surface 8 allows seeds 11 that are dropped into the upper opening 5 of the grow hole 3 to roll down towards the lower opening 6. The top element 4 includes a recess 22 for receiving the base element 9. This recess is defined by edges 23 in an end wall 24 of the top element 4 and by the edges of the cut-out sections 16 of the series of grow holes 3. In this embodiment, the edges 23 and the cut-out sections 16 are arranged at the same slope angle as the substrate support surfaces 8, thus creating complementary or mating surfaces. Corresponding grow holes 3 of the two rows 14 are symmetrical or mirrored. The base element 9 can be loosely placed in the fluid receptacle 13, but can also be attached thereto. It is also conceivable that the fluid receptacle 13 and the base element 9 are integrally made. The base element 9 may comprise or constitute an elongated protrusion arranged on or in the fluid receptacle 13. As such, the support structure 2 may comprise a combination of the base element 9 and fluid receptacle 13 on one hand and the top element 4 on the other. In this embodiment the top element 4 is shown to be a module including six grow holes 3. The base element 9 is shown to extend beyond the top element 4. It will be clear that top elements 4 having more or less than six grow holes 3 may be used, depending on the number of plants to be grown. Multiple top elements 4 may be arranged end-to-end on a single base element 9. In similar manner, multiple base elements 9 may be arranged end-to-end to cover the entire length of a gutter 13. The size of the top elements 4 and base elements 9 may be equal, or top elements 4 may be longer or shorter than base elements 9. Figure 2A shows a top view of the top element 4 of the support structure 2 positioned in a fluid receptacle or gutter 13 with seeds 11 located in the grow holes 3. Fig.2B shows a close-up of the top element 4 after the seeds 11 have started to germinate and become seedlings 1. Fig.2C shows a part of the support structure 2 after having been removed from the gutter. Here the roots 10 of the plant are shown to emerge from the lower openings 6 of the grow holes 3, while the leaves 15 grow from the upper openings 5. The plants can be harvested directly off of the growing system when the top element 4 is positioned on the base element 9, but it is also possible to remove the top element 4 from the base element 9 before harvesting to lift the plants out of the base element 9 for convenient harvesting. Fig.2D shows the underside of the top element 9. It can be seen that roots 10 of the plants grow through the lower openings 6 of the grow holes 3. Fig.2E shows the support structure 2 from the side with the top element 4 lifted from the base element 9. The decomposing substrate 7 is visible. The decomposition allows additional space for the plant root system. The seedlings 1 are large enough to be physically constrained by the walls of the grow holes 3, while enough space is available for the roots 10. Fig.3 shows the different parts of the support structure 2 of the growing system 20 of the invention. Starting at the top, Fig.3 shows the top element 4, the substrate 7, the base element 9, and fluid receptacle or gutter 13. Although base element 9 and fluid receptacle 13 are shown as separate parts, they may be mutually connected or integrated. Fig.4A shows the top element positioned 4 on the base element 9 with a substrate 7 containing a seed 11. It can be seen how the seed 11 is restrained from falling through the hole by the dimensions of the lower opening 6 that is defined in part by the funnel 25 of grow hole 3 and in part by the sloping substrate support surface 8 of the base element 9. As can be seen by comparing the left hand side and right hand side of this figure, the size of the seed 11 determines how far from the lower opening 6 – and thus how far from the liquid nutrient or water 12 in the fluid receptacle 13 it comes to rest in the grow hole 3. Fig.4B shows a detailed view of the cross section of the lower opening 6 and the fluid receptacle 13 of the combined growing system with the seed 11 suspended over the liquid nutrient 12. Fig.5A shows a cross-sectional view of the top element 4 positioned on a base element 9, wherein the base element 9 comprises a triangular protrusion as shown in Fig.1 and Fig.4. Fig.5B1 shows an exemplary embodiment wherein the protrusion has a trapezoid shape, including two sloping surfaces 8 on opposite sides connected by a flat top surface 27. This leads to a stronger and stiffer top element 4, as the recess 22 may be shallower and a larger part of the structure is maintained as compared to the triangular recess of Figs.1 and 4. On the other hand, there is less room for the cut-out section 16 and the substrate 7. Fig.5B2 shows a perspective view of the support structure 2 of Fig.5B1. This view shows only a relatively small part of the top element 4, including only four grow holes 3. Fig.5C shows a cross section of the top element 4 positioned on the base element 9, wherein the cross-section also shows the grow holes 3 and their upper openings 5 and lower openings 6. In this embodiment the grow holes 3 on opposite sides of the base element 9 are shown to be in different positions and to have different dimensions. This asymmetry in the top element 4 results in cut-out sections 16 having different areas, and consequently in different amounts of substrate 7 being available for contact with the propagation material. This cross section also shows seeds 11 of different sizes accommodated in the juxtaposed grow holes 3. Fig.5D1 shows a cross section of an alternative embodiment wherein the base element 9 includes a trapezoidal protrusion which is asymmetrical with regard to the slope angles α1 and α2 of its respective substrate support surfaces 8. These different slope angles also result in cut-out sections 16 having different areas, and consequently in different amounts of substrate 7 being available for contact with the propagation material. Fig.5D2 shows a general view of the support structure 2 of the grow system as shown in Fig. 5D1, again showing only a relatively small part of the top element 4, including no more than four grow holes 3. The photograph of Fig.6A shows a top perspective view of an alternative embodiment of a support structure 102 of the invention. This embodiment has a single row of grow holes 103, only one of which is shown here. In this embodiment the top element 104 has an inverted L-shape in cross- section. The top element 104 includes a substantially horizontal part 126 which comprises the grow hole 103. It further includes a substantially vertical part or protrusion 119, which extends downward from the horizontal part 126. The base element 109 has a sloping surface 108A on one side, a flat top 127 and a substantially vertical surface 108B on the opposite side. The top element 104 includes a recess 122 having a sloping edge 123 substantially matching the sloping surface 108A of the base element 109 and a flat bottom 128 matching the flat top 127 of the base element 109. As such, the shape and size of the recess 122 of the top element 104 are designed to fit the base element 109 in a tight fashion, also by means of the additional vertical part or protrusion 119 on the far side of the base element. The grow hole 103 in this embodiment comprises tooth-like protrusions 117 extending into the lower opening 106. Between these protrusions 117 slit-like recesses 118 are defined. As such, the lower opening 106 has a serrated edge. The purpose of the protrusions is to partially obstruct the lower opening, thus holding the seed 111. On the other hand, the recesses 118 serve to provide additional space for roots to grow. A segment 116 of the lower opening 106 is kept free of protrusions. This segment 116 is covered or closed of by the sloping surface 1088 of the base element 109 when the top and base elements 104, 109 are assembled. In this way, the top element 104 and base element 109 together define the grow hole 103, more in particular the dimensions of its lower opening 106. The photograph of Fig.6B shows a top perspective view of this specific embodiment from another angle. Here the grow hole 103 is shown to contain a seed 111. The photograph of Fig.6C shows a top perspective view of the base element 109 and top elements 104 when disassembled. Fig.7 shows a drawing of the top element 104 and the base element 109 of the embodiment of Fig.6A-C when disassembled. Although the embodiment of Figs.6 and 7 is shown without any substrate, it will be apparent that a substrate material could be arranged between the top element 104 and base element 109. This substrate material would then also play its role in covering or closing off the cut-out segment of the lower opening 106. On the other hand, it should also be apparent that the embodiments of Figs.1-5 could also be used without a substrate material. In that case the grow hole would be defined only by the top and base elements. Although the invention has been described by reference to various embodiments, it will be apparent that many variations and modifications are conceivable within the scope of the appended claims.

Claims

CLAIMS 1. A hydroponic growing system for growing plants, which system comprises a support structure for propagation material which comprises at least one grow hole, which grow hole is a through hole having an upper opening and a lower opening, wherein the upper opening is wider than the lower opening, the upper opening being wide enough for receiving propagating material and the lower opening being narrow enough to prevent the propagating material from falling through but wide enough to provide passage to roots of the growing plants.

2. Growing system as claimed in claim 1, wherein the propagation material comprises seeds, germinated seeds, seedlings, plantlets, or cuttings.

3. Growing system as claimed in claim 1 or 2, wherein the support structure further comprises at least one fluid receptacle for receiving a liquid nutrient or water.

4. Growing system as claimed in any one of the preceding claims, wherein the support structure comprises a base element and a top element positioned on the base element, wherein the base element and the top element together define at least a part of the grow hole.

5. Growing system as claimed in claim 4, wherein a major part of the grow hole is comprised in the top element and the dimensions of the lower opening of the grow hole are defined by the base element.

6. Growing system as claimed in claim 4 or 5, further comprising a substrate material located in between the top element and the base element, wherein the substrate material is in contact with the lower opening of the grow hole.

7. Growing system as claimed in claim 6, wherein the substrate material is cloth or paper or a composite thereof.

8. Growing system as claimed in any one of claims 4-6, wherein the base element has at least one substrate support surface for supporting the substrate material thereon, and a part of the lower opening of the grow hole is arranged to face the substrate support surface, and wherein the substrate support surface is arranged to cover the facing part of the lower opening of the grow hole, such that an uncovered section of the lower opening of the grow hole is narrow enough to prevent propagation material placed in the grow hole from falling through, but wide enough to provide passage to roots of the growing plants.

9. Growing system as claimed in claim 8, wherein the at least one substrate support surface is sloped with respect to the horizontal plane of the base element.

10. Growing system as claimed in claim 9, wherein a slope angle of the substrate support surface is between 45 and 90 degrees.

11. Growing system as claimed in any one of claims 4-10, wherein the base element comprises at least one protrusion which is triangular or trapezoid shaped in cross-section for supporting the top element thereby defining the lower opening of the grow hole.

12. Growing system as claimed in any one of the preceding claims, wherein the support structure comprises a plurality of grow holes arranged in a pattern.

13. Growing system as claimed in claim 12, wherein the support structure comprises two longitudinal rows of opposite grow holes, and wherein the juxtaposed grow holes are mirrored.

14. Growing system as claimed in any of the claims 4-13, wherein the top element is separate or separable from the base element.

15. Growing system as claimed in any of the claims 4-14, wherein the top element has an inverted L-shape in cross-section, including a substantially horizontal part comprising the grow hole and a substantially vertical part extending therefrom towards the base element.

16. Growing system as claimed in any one of the preceding claims, wherein the top element comprises at least one protrusion partially obstructing the lower opening and recesses providing additional space for roots of the propagation material.

17. Growing system as claimed in any of the claims 3-16, wherein the at least one fluid receptacle is a gutter and the propagation material is grown using a nutrient film technique.

18. Growing system as claimed in claim 17 when dependent on claim 4, wherein the base element is arranged in the gutter.

19. Growing system as claimed in any of the claims 3-18, wherein the fluid receptacle is a basin and the propagation material is grown using a deep water culture system.

20. Growing system as claimed in claim 19, wherein the support structure is arranged to float on the water of the deep water culture system.

21. Support structure for use in a growing system as claimed in any one of the preceding claims.

22. Method for growing plants, comprising providing plant propagation material in a growing system as claimed in any one of claims 1-20 and allowing the propagation material to develop into plants, preferably until harvest stage.

23. Method as claimed in claim 22, comprising providing the plant propagation material in a growing system as claimed in claim 17 and allowing the propagation material to develop into plants, preferably until harvest stage, wherein the plants are grown using a nutrient film technique.

24. Method as claimed in claim 22, comprising providing plant propagation material in a growing system as claimed in claim 19 and allowing the propagation material to develop into plants, preferably until harvest stage, wherein the plants are grown using a deep water culture system.

25. Method as claimed in any one of claims 22-24, wherein the plants are vegetables, herbs or sprouts.

26. Method as claimed in any one of claims 22-25, wherein the plant is chosen from the group consisting of lettuce (Lactuca sativa), spinach (Spinacea oleracea), rucola (Eruca vesicaria or Diplotaxis tenuifolia), endive (Cichorium endivia or Cichorium intybus), corn salad (Valerianalocusta), brassica (Brassica oleracea or Brassica juncea or Brassica rapa or Brassica napus or Brassica nigra or Brassica carinata), and Swiss chard (Beta vulgaris).

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