Plant pot for substrate culture

Abstract: The invention relates to a plant pot for substrate cul­ ture in the upper surface whereof is located an opening (1) where­ in a plant (2) can be placed and consisting of water-absorbent material, for example an inorganic material such as rockwool, characterized in that the plant pot has one or more internal cavities (5) closed off toward the upper surface.

Description: The present invention relates to a plant pot for substrate culture in the upper surface whereof is located an opening wherein a plant can be placed and consisting of water-absorbent material, for example an inorganic material such as rockwool. Such a plant pot is known from EP-A-0 176 134. It is applied for the further growth of a germinating plant which is placed for this purpose in the opening located in the upper surface of the plant pot. Furthermore, EP-A-0 176 134 describes a plant substrate of which the bottom surface is provided with one or more grooves opening in the two side surfaces. However, grooves are not internal cavities. During breeding the plant pot is normally placed on a ground over which a quantity of oxygen-rich water with the necessary nutrients is periodically directed according to the so-called ebb and flow system. Such a ground is normally formed by a concrete floor over which the water is guided. The absorptive capacity of the plant pot material is so great that this becomes water-saturated over a considerable part of its height. Besides oxygen from the air the plant takes up oxygen from the water via its roots. The oxygen content of the water drawn up into the plant pot therefore decreases. When the oxygen content falls below a particular threshold value the growth rate of the green parts of the plant begins to diminish (growth stagnation) and stagnation occurs in root growth. This problem occurs especially during the colder, darker seasons when the plant absorbs only a little water because of limited evaporation. In this period it can take several days, for example, before the plant takes so much water from the plant pot that irrigation has to take place again. At the end of this period, however, the oxygen content of the water in the plant pot has already fallen well below the value necessary for normal growth of the plant so that the mentioned growth inhibition occurs. It is noted that this problem occurs either to a lesser degree or not at all during the warmer seasons. Because of the great evaporation which occurs during this period irrigation has to be carried out quite frequently to keep the plant pot sufficiently moist. Fresh water with a proportionally large amount of oxygen is continually added thereby so that the oxygen content remains at the required level. When, however, as mentioned above, the water evaporates only slowly, replacing of the several day old, oxygen-poor water in the plant pot with fresh water could be considered. This would then have to be supplied on the top side of the plant pot. Various factors gives rise however to practical drawbacks. For example, the plant rooted in the plant pot screens a large portion of the top part of the plant pot relative to the supplied overhead irrigation water. It has therefore been found not possible to carry fresh, oxygen-rich water into the plant pot by overhead irrigation. The object of the invention therefore is to provide a plant pot of the type mentioned in the preamble which does not have these drawbacks. This object is achieved in that according to a first embodiment the plant pot has one or more internal cavities being closed off toward the upper surface and having at least one cavity opening onto a side surface or onto a bottom surface, or in that according to a second embodiment the plant pot has one or more internal cavities closed on all sides. Each cavity forms an air chamber into which air can enter as a result of the porosity of the plant pot material. A part of the roots can thereby remain in contact with the air while another part of the same roots is in contact with water. The oxygen extracted from the air by the relevant root parts can be directly supplemented from outside. A further advantage of the cavities according to the invention lies in the proportionally high relative humidity of the air located therein. Since the cavity is enclosed by moist walls, this relative humidity has a value of 80% to 90% which ensures optimal growth. The maintenance of the correct relative humidity is of great importance particularly with very young and therefore vulnerable plants. The plant pot according to the invention is therefore very suitable for application in nurseries. According to a preferred embodiment provision is made that the cavities open onto the bottom surface of the plant pot. When the water level is low enough, fresh, oxygen-rich air can therefore enter the cavities via the bottom surface of the plant pot. Further, if the cavities are displaced relative to the opening in the upper surface the cavities on the one side and the opening on the other can overlap mutually in the vertical height of the plant pot. The invention also relates to plant pots provided with a bottom surface with raised and recessed portions. With these plant pots the best effect is achieved if the cavities open into the recessed portions. Finally, provision can be made that the cavity is closed on all sides. Such a plant pot can be obtained by first manufacturing two plant pot halves for assembly, by arranging a cavity on one or both of the adjoining surfaces for assembly and by thereafter assembling the plant pot halves. The invention will subsequently be further elucidated with reference to several embodiments. Figure 1 shows a first embodiment of the plant pot in cross section; figure 2 shows a perspective view from below of the plant pot according to figure 1; figure 3 shows a second embodiment of the plant pot in cross section; figure 4 shows a third embodiment of the plant pot in perspective from below. The plant pot of water-absorbent material, for example rockwool, depicted in section in figure 1 has the form of a parallelepiped in the upper part whereof a cavity 1 is provided wherein is placed a plug 12 of the same water-absorbent material with a plant 2. The roots 3 of the plant 2 spread from the plug 12 outward through the material of the plant pot, wherein a part of the roots extends into the region below the level to which water is drawn up into the plant pot. This water level is designated schematically by the line 4. From the bottom surface of the plant pot cavities extend in the form of holes 5. As a result of these holes 5 a portion of the roots 3 is in contact with oxygen-rich air with a proportionally high relative humidity. Optimal growth of the plant is thereby stimulated while root rot is countered. As depicted, the roots 3 run only partly through the holes 5. It can also occur here that when a root has followed such a hole 5 it will continue to grow further entirely in that hole 5 without again penetrating into the material of the plant pot. As shown in figure 2, a hole 5 is provided in each case preferably at each corner 6 as well as in the middle of each side of the plant pot. In known manner the plant pot can further be provided on the outside with an envelope 8 of plastic foil. This plastic foil has the purpose of preventing the roots 3 from growing out at the sides 7. In the embodiment according to figure 3 the cavities 9 are arranged in the form of horizontally running channels 9. These channels 9 run preferably from the one side surface 7 to the opposite side surface 7. As shown, the roots 3 also run in this embodiment partly through the channel 9 wherein mainly air will be present. Finally, a plant pot is depicted in figure 4 the underside whereof is provided with recessed portions 10 and raised portions 11. With such a plant pot the holes 5 are preferably arranged in the recessed portions 5 so that they are readily accessible for the surrounding air. Finally, it is also noted that all holes 5 can run through in an upward direction so far that they overlap the opening 1 wherein the plant 2 is placed in vertical direction of the plant pot. The presence of the holes 5 thereby need form no obstacle whatever to making the opening 1 deeper, should this be required in view of the sort of plant.

Claims: Plant pot for substrate culture, in the upper surface whereof is located an opening wherein a plant can be placed and consisting of water-absorbent material, for example an inorganic material such as rockwool, characterized in that the plant pot has one or more internal cavities being closed off toward the upper surface and having at least one cavity opening onto a side surface or onto a bottom surface. Plant pot for substrate culture, in the upper surface whereof is located an opening wherein a plant can be placed and consisting of water-absorbent material, for example an inorganic material such as rockwool, characterized in that the plant pot has one or more internal cavities closed on all sides. Plant pot as claimed in claim 1, characterized in that the cavities open onto the bottom surface of the plant pot. Plant pot as claimed in claim 1 or 3, characterized in that at least one cavity opens one side surface of the plant pot. Plant pot as claimed in claim 4, characterized in that at least one cavity opens onto two side surfaces. Plant pot as claimed in any of the preceding claims 1, 3-5, provided with a bottom surface with raised and recessed portions, characterized in that the cavities open into the recessed parties. Plant pot as claimed in any of the preceding claims 1-6, characterized in that the cavities are displaced relative to the opening in the upper surface. Plant pot as claimed in any of the preceding claims 1-7, characterized in that a cavity is provided close to each corner point and close to the middle of each side. Plant pot as claimed in any of the preceding claims 1-8, characterized in that the cavities on the one side and the opening on the other overlap mutually in vertical direction of the plant pot. Method for manufacturing a plant pot as claimed in claims 1-9, characterized in that two plant pot halves for assembly are manufactured, that at least one cavity is arranged on one or both adjoining surfaces for assembly and that thereafter the plant pot halves are assembled.

Inventors: VAN GORKOM JOHANNES CORNELIS P, VAN GORKOM, JOHANNES CORNELIS PETRUS MARIA
Applicants: ROCKWOOL GRODAN BV, ROCKWOOL/ GRODAN B.V.
Application year: 1990
Main classification: A01G31
IPC codes: A01G31