Abstract:
A modular field planting system adapted for installation on a roof surface includes an arrangement of substantially identical tray members with each tray member containing two tray compartments. An array of first tray members is positioned on the roof surface with the tray members being in contiguous relationship and oriented in a first direction. A second tray member positionable in overlying relationship with respect to the first tray and rotated 90° with respect to the first direction, is nestably seated within corresponding tray compartments in each of two adjacent first tray members. A wicking material in the first tray member is placed in communication with a wicking material in the second tray member when the respective first and second tray members are seated. The first tray member is adapted to provide a reservoir for water and the second tray member is adapted to retain a growth medium whereby the wicking material provides continuous moisture migration for hydrating the growth medium.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the benefit of U.S. Provisional Application Ser. No. 60/720,229 filed Sep. 23, 2005 and incorporates same herein by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention relates to plant husbandry and especially to sheet or field planting suitable for urban environments. 
   In particular, the invention concerns a modular field planting system suitable for a rooftop garden. 
   2. Description of Related Art 
   The integration of living plants within an urban environment can provide aesthetic, ecologic and economic benefits. For example, rooftop gardens, also known as green roofs, have been found to reduce air and noise pollution, recycle carbon dioxide, control building heating and cooling costs, absorb roof rain runoff and eliminate water pooling, prolong roof life by avoiding direct exposure to solar energy, and prevent blockage of roof drainage systems by trapping debris. Furthermore, roof top vegetation can prevent and/or retard the spread of fire through the roof structure. Additionally, rooftop gardens can create new recreational space which is of particular significance within a crowded urban environment. 
   Rooftop gardens are typically designed by placing a layer of ordinary soil spread onto a roof surface. A distinct problem of this arrangement is that the structural integrity of the roof may be compromised unless the roof is reinforced for the additional deadload. Another shortcoming of rooftop gardens is that the roots from the vegetation can penetrate and damage the roof surface. Furthermore, the roof surface must be adequately waterproofed to prevent leakage as a result of drainage from the overlying soil. The aforementioned rooftop garden systems also require professional installation and maintenance and can present difficulties if there is a need to access the underlying roof surface. 
   Another more easily maintainable roof gardening arrangement involves freestanding planters, pots and/or containers. However, this arrangement does not readily provide continuous coverage of the roof surface. Rectangular planters may provide improved coverage however a disadvantage of rectangular planters is that the top edges of the several adjacent planters are visible and it does not create the appearance of a unitary field planting. Another problem with growing plants in pots, planters, or containers, is that the restricted space for lateral root spread can result in detrimental loss of nutrients and water necessary to sustain the plants. A further limitation is that planters and the like, placed on a roof surface are subject to over-turning due to wind forces and are particularly unstable on sloped roof surfaces. Another disadvantage of independent planters is that they must be separately watered and with shallow potting systems water retention is of particular concern. 
   Previous planter devices have attempted to provide a self-contained water source such as disclosed in U.S. Pat. No. 6,357,179. Although the patented device describes a water reservoir, it does not rely upon a wicking medium for delivering constant moisture. Furthermore, the patented concept does not involve an expansive growth pattern as in field planting. The wicking system described in U.S. Pat. No. 4,219,967 is intended for use with a flowerpot or planter and does not contemplate incorporation within a field planting system as in the present invention. 
   BRIEF SUMMARY OF THE INVENTION 
   Briefly, this invention concerns a field planting system for a green roof utilizing a martrix of modular tray members. The trays members are positionable in a functionally cooperative bi-level relationship with an upper tray member accommodating a growth medium and a lower tray member providing a water reservior. A wicking material, in communication with the respective tray members hydrates the growth medium. 
   An aspect of this invention is that the tray members can be readily placed on a roof surface without requiring professional installation and/or maintenance. 
   Another aspect of this invention is that a tray member arrangement can be designed to provide continuous roof coverage. 
   A still further aspect of this invention is that the tray members are preferably shallow in depth, light in weight, and water impervious, for compatibility with existing roof structures. 
   Still another aspect of this invention is that selected tray members may be easily removed for accessing an underlying roof surface without disturbing the remaining tray members. 
   An additional feature of this invention is that the tray members are interlocked for positive load transfer and for resisting wind forces. 
   Having thus summarized the invention, it will be seen that it is a preferred object thereof to provide an improved modular field planting system of the general character described herein which is not subject to the previously mentioned limitations. 
   Another preferred object of this invention is to provide an improved modular field planting system defined by an interlocked network of nestable tray members. 
   Still another preferred object of this invention is to provide an improved modular field planting system that will maintain a substantially continuous moistening of a growth medium. 
   Yet another preferred object of this invention is to provide an improved modular field planting system that will not damage a supporting roof surface. 
   Yet still another preferred object of this invention is to provide an improved modular field planting system that is economical to manufacture, relatively simple to install, and easy to maintain. 
   With these ends in view, the invention finds embodiment in certain combinations of elements and arrangements of parts by which the aforementioned preferred objects and certain other objects are hereinafter attained, all as more fully described with reference to the accompanying drawings and the scope of which is more particularly pointed out herein. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings, in which is shown an exemplary embodiment of the invention: 
       FIG. 1  is a plan view of a tray member of this invention showing two tray compartments and a pattern of wicking strips extending interiorly within the tray compartments in both a transverse and a longitudinal direction; 
       FIG. 2  is a plan view showing two tray members and an overlying third tray member, with a portion cut away for illustrative purposes, nestably engaged within the two tray members; 
       FIG. 3  is a sectional view taken substantially along line  3 - 3  of  FIG. 2  illustrating the nestable engagement of the tray members; 
       FIG. 4A  is a sectional view, to an enlarged scale, of a portion of a marginal flange of two adjacent tray members, corresponding to the area identified in  FIG. 3 , showing the contiguous relationship of the wicking strips; and 
       FIG. 4B  is a sectional view, to an enlarged scale, of a portion of the nested tray members, corresponding to the area identified in  FIG. 3 , showing the juncture of the wicking strips between the respective tray members. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   With specific reference now to the figures in detail, it is stressed that the particulars shown are by way of example and for the purposes of illustrative discussion of the preferred embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt has been made to show aspects of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings should make it apparent to those skilled in the art how the several forms of the invention may be embodied in practice. 
   Referring now to  FIG. 1  of the drawings there is shown a typical tray member  10  of this invention. The tray member  10  is substantially rectangular in plan view and defines two tray compartments  12 ,  14 . In view of the congruous relationship of the tray compartments  12 ,  14 , the following description will be made with reference to tray compartment  12 , it being understood that tray compartment  14  is similarly configured. The tray compartment,  12  is defined by complimentary sets of opposed sloped sidewalls  16 ,  18  and  20 ,  22 , and a bottom wall  24  spanning between the two sets of opposed sidewalls and provided with a plurality of depending legs  26 . The legs  26  elevate the tray member above a support surface to provide for aeration, and when placed on a roof surface, will allow the roofing membrane to “breathe”. The sloped sidewalls,  16 ,  18  include respective marginal flanges  28 ,  30 . It should also be noted that the set of sidewalls  16 ,  18  is provided with respective wedge-shaped braces  32 ,  34 , the function of which will be described hereinafter. The sidewalls  16 ,  18  also include respective nib members  36 ,  38  and the sidewalls  20 ,  22  include apertures  40 ,  42  that register with the nib members  36 ,  38  when the tray members  10  are assembled in a functional mode. 
   Further with regard to the fabrication of the tray member  10 , a score-line  44  is preferably incorporated within the manufacturing process between the tray compartments  12 ,  14  so as to provide frangibility as needed, for separation of the respective tray compartments  12 ,  14 . 
   By way of example, the tray member  10  may be fabricated of a light-weight, water-impervious, PVC plastic or equivalent material, and may be vacuum-formed and/or injection molded as an integral unit. It should also be understood that the designation “tray member” is intended to encompass a range of open receptacles. Although the tray member  10  is shown and described as being substantially rectangular and as having dual compartments,  12 ,  14 , a tray member  10  having an alternative geometric shape and an alternative number of tray compartments is within the scope of this invention. 
   As shown in  FIG. 1 , the tray compartments  12 ,  14  are provided with an orthogonal pattern of wicking strips  46  extending in a transverse and in a longitudinal direction. The wicking strips  46  are placed along the bottom wall  24 , up the respective sidewalls  16 ,  18 , and  20 ,  22  and extends over the marginal flanges  28 ,  30  slightly beyond the respective edge of the flanges  28 ,  30  and slightly over the top edge of the sidewalls  20 ,  22 . It should also be noted that the wicking strips  46  also extends over the respective nib members  36 ,  38  and the respective apertures,  40 ,  42 . By way of example, the wicking strips  46  can be made of an absorbent fabric such as a non-woven, needle-punched polyester material or the like that will provide for migration of moisture by capillary action. Additionally, in lieu of the wicking strips  46 , a continuous sheet of a wicking material may be utilized. 
   With regard to the operational assembly of the tray members for providing field planting coverage of a surface, there is shown in  FIG. 2  two adjacent tray members designated  10 A,  10 B, lying in one direction (e.g. on a roof surface) with the marginal flanges  28 ,  30  overlapping. An upper tray member  10 C, has been rotated 90° with respect to direction of the tray members  10 A,  10 B, to register the complimentary sets of opposed sidewalls and is nestably seated within corresponding tray compartments in each of the tray members  10 A,  10 B as shown in  FIGS. 2 and 3 . For the purposes of clarity the reference numerals as applied to the corresponding elements in the tray member designated  10 C include the suffix “c”. It should be noted that when the tray member  10 C is fully seated, the nib members  36 ,  38  of tray member  10 A will register with the respective apertures  40   c  and  42   c  (not shown) for snap-fit or equivalent engagement. Furthermore the wicking strips  46  extending from the tray members  10 A,  10 B are urged, by the respective nib member  36  and  38 , through the apertures  40   c  and  42   c  and into contact with the wicking strips  46  of the tray member  10 C as shown in detail in  FIG. 4B . 
   It should also be observed that the distance dimension between the sidewalls  16 ,  18  is slightly greater than the distance dimension between the sidewalls  20 ,  22 . This configuration will limit the vertical displacement of the overlying tray member  10 C into the lower tray members  10 A,  10 B to thus define a chamber for retaining water. The braces  32 ,  34  in the tray member  10 A are used to hold the sidewalls  20   c ,  22   c , apart from the sidewalls  16 ,  18  in the tray member  10 A during nestable seating and also provide stability and help to align the apertures  40   c ,  42   c , with the nib members  36 ,  38 , when the tray members  10 A,  10 B,  10 C are nested as shown in  FIGS. 2 and 3 . 
   Although this preferred embodiment was described using substantially identical tray members  10 , a similar interaction between respective tray members is achievable using a combination of variant tray members. For example, an upper tray member may be shallower in depth than the lower tray member yet nestably engageable with the lower tray member. 
   It is also considered within the scope of this invention to configure the tray compartments with substantially vertical, rather than sloped sidewalls, and to limit vertical displacement of the upper tray member within the lower tray member by providing a “stop” in the form of an offset or “step” in the sidewall of either or both tray compartments. 
   It should be obvious that to accomplish a field planting another array of tray members  10  can be placed adjacent to the first set of engaged tray members to form a grid for providing continuous surface coverage. At the edging along the periphery of the field planting, the tray members  10  may be separated along the score-line  44  to provide a uniform boundary. 
   In accordance with the purpose of this invention, the tray member  10 A is provided with a growth medium  48 , preferably having high absorbency and water retention characteristic for supporting vegetation (e.g. grass, plants, shrubs). Typically, the growth medium  48  can consist of non-organic mineral components and/or artificial soil such as vermiculite or perlite and preferably, should be engineered to weigh less than the weight of conventional soil. The growth medium  48 , preferably extends above the upper edge of the sidewalls  16 ,  18  and  20 ,  22 . 
   Further in accordance with this invention, the tray members  10 A,  10 B, will function as a reservoir for supplying hydration to the growth medium  48 . 
   It should also be apparent that a quantity of water  50  placed in the tray members  10 A,  10 B will migrate via the wicking strips  46 , in a generally vertical direction, to the tray member  10 C and through the growth medium  48 . Additionally, rainwater collected in the upper tray member  10 C will be transmitted via the wicking strips  46 , to the lower tray members  10 A,  10 B. This prevents oversaturation of the growth medium  48  which can be damaging to the vegetation roots. It should be further noted that the water  50  in the tray members  10 A,  10 B will migrate, in a generally horizontal direction, to adjacent tray members via the wicking strips  46  of adjacent tray members in contact along the marginal flange  28 ,  30  as shown in  FIG. 4A . In this regard, it should be observed that the portion of the wicking strip  46  that extends beyond the edge of the flanges  28 ,  30  is wrapped under the upper of the mating flanges  28 ,  30  to place the wicking strip  46  on the respective flanges  28 ,  30  in contact. The portion of the wicking strips  46  extending above the sidewalls  20 ,  22  overlap at the respective confronting edges for water migration and for preventing the growth medium  48  from falling between the tray members  10 A,  10 B. The horizontal water migration will reduce the need to water each tray member. Also designated upper tray members can be filled with gravel, rather than a growth medium  48 , to function as a rainwater collector for replenishing the water  50  in the lower tray member. 
   Note also that apertures  40 ,  42  in the tray members  10 A,  10 B will provide overflow protection; when the water  50  reaches the level of the apertures,  40 ,  42  it will flow out of the tray members  10 A,  10 B. 
   It should thus be seen that there is provided an improved modular field planting system which achieves the various preferred objects of this invention and which is well adapted to meet conditions of practical use. Since other various possible embodiments might be made of the present invention or modifications might be made to the exemplary embodiments set forth above, it is to be understood that all materials shown and described with reference to the accompanying drawings are to be interpreted as illustrative and not in a limiting sense.