Abstract:
The present invention relates to a device for covering a plant growing medium. The device includes a sheet that defines an aperture. One or more protrusions extend from the sheet to engage a top surface of the plant growing medium. A wall is integrally attached to each edge of the sheet. Each wall has a series of ridges.

Description:
FIELD OF INVENTION 
       [0001]    The present invention relates to a device for covering a plant growing medium. 
       BACKGROUND OF INVENTION 
       [0002]    There are a number of situations in which it may be desirable to cultivate plants without having to use soil. For example, during the colder months of the year, some gardeners begin growing seedlings indoors in anticipation of spring. This process is more simple and sanitary when soil is not used. 
         [0003]    Growing mediums other than soil may be used to germinate seeds. One popular growing medium is rockwool. Rockwool is used extensively for hydroponic growing systems. Rockwool is made by melting a combination of rock and sand and spinning the mixture. This results in fibres that may be formed into different shapes and sizes. 
         [0004]    Rockwool absorbs and maintains water. Further, rockwool is porous and thus retains oxygen. As a result, plants that grow in rockwool have healthy root systems. Finally, rockwool can be formed into a number of shapes and sizes. Frequently, rockwool fibres are compressed into cubes. 
         [0005]    Before using a rockwool cube, the cube must be treated by soaking it in a nutrient solution to adjust its pH level. Further, once seeds or seedlings are placed in rockwool, the rockwool is periodically watered. Therefore, rockwool is moist when in use. 
         [0006]    The moisture of rockwool cubes creates some difficulties for gardeners. Specifically, when rockwool is exposed to the light that is normally used for indoor germination and cultivation of plants, algae forms on the surface of the moist rockwool cubes. Such algae attracts insects such as fungus gnats and shoreflies. Further, when algae decays and dies, it can become detrimental to plants since it may invite bacteria and viruses. Algae can even compete with the plants being grown for oxygen, which is necessary for nutrient uptake. 
         [0007]    To prevent the growth of algae on rockwool, it is necessary to deprive the algae of light. Algae flourishes in wet, well lit locations and depriving it of light prevents photosynthesis. 
         [0008]    Various solutions have been proposed for covering rockwool cubes to prevent the growth of algae. However, previously disclosed rockwool cube covers suffer from a number of disadvantages. First, such covers limit the circulation of oxygen, thus creating an anaerobic environment. This inhibits nutrient uptake by the plant. Further, some previously disclosed cube covers are simply sheets of plastic that are placed above the cube and frequently engage the surface of the cube, thus further inhibiting the circulation of oxygen. Finally, previously disclosed cube covers are not durable. 
       SUMMARY OF INVENTION 
       [0009]    An object of the invention is to provide an improved cube cover for use with plant growing mediums. 
         [0010]    Accordingly, the invention herein comprises a device for covering a plant growing medium comprising a sheet. The sheet defines an aperture. Further, the sheet has at least one protrusion projecting from the sheet for engaging a top surface of the plant growing medium. 
         [0011]    Descriptive references herein such as “planar”, “parallel”, “perpendicular”, “normal”, “straight”, “horizontal” or “vertical” are for convenience of description only. It will be appreciated by one skilled in the art that the placement of elements may depart moderately from a planar, parallel, perpendicular, normal, straight, horizontal or vertical configuration. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    In drawings which illustrate by way of example only a preferred embodiment of the invention: 
           [0013]      FIG. 1  is a perspective view of a bottom surface of the cube cover; 
           [0014]      FIG. 2  is a perspective view of a top surface of the cube cover; and 
           [0015]      FIG. 3  is a sectional view of the cube cover along line  3 - 3  of  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0016]    A cover  10  for a plant growing medium is shown in  FIGS. 1 and 2 . The cover  10  is constructed from a suitably rigid material such as plastic. 
         [0017]    The cover  10  has a sheet  20 . The sheet  20  may be of any shape or size so as to cover the surface or surfaces of a plant growing medium that are directly exposed to light sources of the type frequently used for indoor growing. In the embodiment shown in  FIGS. 1 and 2 , the sheet  20  is square. Preferably, the sheet is substantially planar. Further, the sheet  20  has four edges  22 ,  24 ,  26  and  28 . The four edges  22 ,  24 ,  26  and  28  meet at four corners  30 ,  32 ,  34  and  36 . 
         [0018]    The sheet  20  defines an aperture  40 . The aperture  40  may have any shape or size. In the embodiment shown in  FIGS. 1 and 2 , the aperture  40  is circular. The aperture  40  shown in  FIGS. 1 and 2  is orientated at the centre of the sheet  20 . It will be apparent to a person skilled in the art that it is not necessary for the aperture  40  to be orientated at the centre of the sheet  20 . The aperture  40  may also be in a different position in the sheet  20  such as near one of the edges  22 ,  24 ,  26  or  28  of the sheet  20  or near one of the corners  30 ,  32 ,  34  or  36  of the sheet  20 . 
         [0019]    At least one protrusion projects from the sheet  20 . In the embodiment shown in  FIGS. 1 to 3 , there are four protrusions  44  projecting from the sheet  20 . It will be apparent to a person skilled in the art that the objects of the invention may be satisfied by any number of protrusions projecting from the sheet  20  and embodiments incorporating one or moreprotrusions are contemplated. 
         [0020]    As seen in  FIG. 1 , each protrusion is barrel-shaped with beveled walls. The bevelled walls of the protrusion may meet at a point (not shown). In the embodiment shown in  FIGS. 1 and 2 , each protrusion has a surface  60 . Preferably, each of the surfaces  60  is parallel to the plane of the sheet  20 . The protrusions are each orientated proximate to a separate corner of the sheet  20 . 
         [0021]    A preferred embodiment of the protrusions  44  is shown in  FIGS. 1 and 2 . Protrusions having other shapes and orientations are contemplated. 
         [0022]    As seen in  FIG. 2 , each of the protrusions  44  is hollow. It will be apparent to a person skilled in the art that the objects of the invention may be achieved if the protrusions are solid and this is contemplated. 
         [0023]    As seen in  FIGS. 1 and 2 , in a preferred embodiment of the cover, four walls  62 ,  64 ,  68  and  72  are integrally attached to edges  22 ,  24 ,  26  and  281  respectively. In the embodiment shown in  FIGS. 1 to 31  each of the walls  621   641   68  and  72  is in a plane perpendicular to the plane of the sheet  20 . Each of the walls  62 ,  64 ,  68  and  72  has a flange  80  at an end of the wall opposite to the end of the wall that is integrally attached to the sheet  20 . 
         [0024]    In a preferred embodiment, each of the walls  62 ,  64 ,  68  and  72  opposes one of the other walls. 
         [0025]    As seen in  FIG. 1 , two of the opposing walls  62  and  68  define a slit  90 . In a preferred embodiment, each of the slits  90  is elongated and positioned in the centre of the wall. Each of the slits  90  enhance the circulation of air proximate to the plant growing medium. 
         [0026]    Each of the walls  62 ,  64 ,  68  and  72  has a number of ridges  100 . Each of the ridges  100  extend from a point at which the flange  80  meets the walls  62 ,  64 ,  68  and  72  beyond a point at which the edges  22 ,  24 ,  26  and  28  of the sheet  20  meet the walls  62 ,  64 ,  68  and  72 . 
         [0027]    From the inside of the cover  10 , each of the ridges  100  is convex or bowed outward. Further, the ridges  100  are parallel to one another and the ridges  100  other than the ridges  100  orientated where the walls  62 ,  64 ,  68  and  72  meet are equidistant from one another. Each of the slits  90  bisect one or more of the ridges  100 . 
         [0028]    As seen in  FIG. 3 , in operation, the cover  10  is placed upon a plant growing medium  110 . The plant growing medium  110  can be any suitable medium for growing plants including soil and rockwool. The shape and dimensions of the cover  10  must be such that the cover  10  fits on the plant growing medium  110 . Specifically, the distance between opposing walls  60  and  68  of the cover  10  must be greater than the distance between opposing walls  112  and  114  of the plant growing medium. 
         [0029]    When the cover  10  is placed on the plant growing medium  110 , the surface  60  of each protrusion engages a top surface  116  of the plant growing medium  110 . For optimal performance, when the cover  10  is placed on the plant growing medium, none of the walls  62 ,  64 ,  68  or  72  of the cover  10  should engage the plant growing medium. In a preferred embodiment, each of the walls  62 ,  64 ,  68  and  72  is positioned in a plane parallel to a plane of the walls of the plant growing medium  110  upon placement of the cover  10  on the plant growing medium  110 . 
         [0030]    Numerous modifications may be made to the embodiment described above without departing from the scope of the invention which is defined by the claims.