Abstract:
A device and method are disclosed for protecting plants from cold weather damage. A transparent, fluid-filled enclosure encircles a plant above the ground. A heater warms the fluid, which in turn warms the plant.

Description:
FIELD OF THE INVENTION 
     This invention relates to a device and method for protecting plants from cold weather. 
     BACKGROUND OF THE INVENTION 
     Many plants, such as tomatoes, have growing seasons shortened by cold weather, thus lessening food production. These plants can be started or grown in greenhouses, but this is expensive. 
     Various types of outdoor plant heaters exist. Smudge pots burn oil to warm plants, such as citrus trees. However, the use of smudge pots is unsatisfactory. Hot air and combustion products rise rapidly from the level of the plants, especially if there is a wind, and soot is produced during combustion. 
     Other plant heaters spray warm water over plants, but this can lead to over-watering and requires a continuous water source. Still other heaters circulate warm ground water through a thermal barrier adjacent to a plant before spraying the water over the plant or directly onto the ground. 
     Still other plant heaters employ vented, transparent plastic covers to enclose plants, but have no active heating element, relying instead on unpredictable and intermittent sunshine, and do not warm the roots of the plant. 
     U.S. Pat. No. 4,137,667 teaches a method of protecting a plant from cold weather by interposing a water layer enclosed in transparent plastic between the plant and the outside atmosphere. However, the device does not include a heater to prevent the water from freezing, nor a means for heating the roots of the plant. 
     U.S. Pat. No. 5,575,109 teaches a plant protection device with a double-walled enclosure. However, the portion of the device extending above the ground is single-walled and there is no disclosure of heated fluid within the double-walled portion of the enclosure. 
     In summary, while other plant heaters exist, no one has developed a gardening device or method that warms a plant by surrounding it with a double-walled container full of fluid warmed by a heater, yet does not require a continuous water source. 
     The primary objective of this invention is to fulfill the above described need with a new gardening device consisting of a double-walled enclosure, adapted for filling with fluid, of a size sufficient to completely encircle a plant, fluid filling the double-walled enclosure and a heater operatively connected to a wall of the enclosure for heating the fluid within the double-walled enclosure. 
     A further object of the present invention is the provision of a method for keeping a plant warm. 
     These and other objects, features and/or advantages of the present invention will become apparent from the specification and claims. 
     SUMMARY OF THE INVENTION 
     The foregoing objects may be achieved by a device comprising a double-walled enclosure, adapted for filling with fluid, of a size sufficient to encircle a plant, fluid filling the double-walled enclosure and a heater operatively connected to the wall of the enclosure. 
     According to another feature of the invention, the device includes an elongated heating member extending from above ground to a determined depth below ground, and a second heater connected to and causing heating of the elongated heating member. 
     According to another feature of the invention, the device includes a vented lid removably mounted to the top of the double-walled enclosure. 
     According to another feature of the invention, the device includes a trellis removably mounted to the double-walled enclosure for supporting a plant growing above the double-walled enclosure. 
     According to another feature of the invention, the device includes a cover surrounding the trellis. 
     According to another feature of the invention, the device includes a fluid circulation pump for circulating fluid within the double-walled enclosure. 
     The method of the present invention comprises positioning a double-walled enclosure around a plant and adjustably heating the fluid to maintain the plant above a critical temperature. 
     According to another feature of the invention, the method includes positioning a heating member underground near the roots of the plant, and applying heat to the heating member. 
     According to another feature of the invention, the method includes positioning a vented lid on top of the enclosure. 
     According to another feature of the invention, the method includes positioning a trellis on top of the enclosure. 
     According to another feature of the invention, the method includes positioning a cover around or over the trellis. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view of a gardening device. 
     FIG. 2 is an exploded view of the gardening device. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIGS. 1 and 2,  10  designates a gardening device. 
     A double-walled enclosure  12  includes an outer wall  14 , an inner wall  16 , a top wall  18  and a bottom wall  20 . The double walled enclosure  12  may be made of any suitable material such as plastic. The walls define an annular space  22 . The walls may be opaque, translucent or, preferably, transparent. The annular space is filled with fluid  24  through a fill hole  26  that is sealed with a cap  28 . The fluid  24  may be water, but aqueous solutions and other fluids may be used. 
     Pockets  30  attach to the outer wall  14  and include receptacles  31  which removably receive and support vertical members  32  of the trellis  34 . The trellis  34  may be made of any suitable material such as plastic, wood or metal. Horizontal members  36  of the trellis  34  connect the vertical members  32 . While the trellis  34  is shown to be cylindrical, it may also lie in a single plane or be square, or any other enclosed shape that forms a cage for containing the plant being grown. A plastic cover  38  is cylindrical in shape and fits around the trellis  34  and is fastened with fasteners  40 . The plastic cover  38  may be opaque, translucent or, preferably, transparent. The fasteners  40  may be hook and loop fasteners. 
     A first heater  42  and circulation pump  44  attach to the outer wall  14 . The first heater  42  may be an electric heater. Heater  42  is shown with a heating element inside annular space  22 , but it is also possible to place the heater totally outside the outer wall  14 . Furthermore, the heater  42  may be placed inside the inner wall  16 . When placed inside inner wall  16  it may be either totally inside inner wall  16  or it may have a heating element positioned inside annular space  22 . The circulation pump  44  may be an electric circulation pump. A removable, vented lid  46  attaches to the top wall  18 . The vented lid  46  may be made out of any suitable material such as plastic and may be opaque or, preferably, transparent. 
     Stakes  48  may optionally be attached to the bottom wall  20  for fastening the enclosure to the ground  50 . The stakes  48  may be made of any suitable material such as plastic, wood or metal. The top of a plant  52  sits inside the cylindrical space defined by the inner wall  16 . The roots of the plant  54  sit beneath the ground  50  under the top of the plant  52 . 
     A second heater  56  attaches to the outer wall  14 . The second heater  56  may be an electrical heater. Attached to the second heater  56  is an elongated heating member  58  buried in the ground  50  near the roots of the plant  54 . It is possible to eliminate second heater  56  and instead mount heating member on outer wall  14  or inner wall  16  in such a manner that it conducts heat from the heated water through the walls  16  or  14  to heat the soil beneath roots  54 . 
     A gardener can employ the gardening device  10  early in a growing season to get a head start on a garden. After planting a seed or plant outdoors, the gardener can encircle the seed or plant with the double-walled enclosure  12 . The stakes  48  anchor the double-walled enclosure  12  to the ground. The gardener can then fill the double-walled enclosure  12 , through the fill hole  26 , with water, an aqueous solution or other fluid  24  and cap the fill hole with the cap  28 . The gardener can heat the fluid  24  by adjusting the first heater  42  that is operatively connected to the double-walled enclosure  12 . The heated fluid  24 , in turn, warms the plant. The gardening device  10  optionally includes the circulation pump  44  to circulate the warmed fluid from the first heater  42  to all through the annular space  22 . 
     Once the double-walled enclosure  12  is around the plant, such as a tomato plant, the gardener can optionally pile dirt inside the enclosure around the stem of the plant to root up the stem. Optionally, the garden device  10  includes the second heater  56  connected to and causing heating of the elongated heating member  58 . The gardener can bury the elongated heating member  58  in the ground  50  to warm the roots of the plant  54 . 
     The drawings show the double walled structure  12  resting on the upper surface of the soil  50 , but it is also possible to excavate soil  50  and bury the lower end of double walled structure several inches in the soil  50 . This will further stabilize device  10  and will also impart heat to the top several inches of soil  50 . 
     The gardening device optionally includes the vented lid  46  removably mounted to the top of the double-walled enclosure  12 . The vented lid  46  helps to retain heat around the plant, yet allows some air-circulation. Once the plant has grown sufficiently, the gardener can remove the vented lid  46  from the top of the double-walled enclosure and, optionally, mount the trellis  34  into the receptacles  31  to support the plant in growing above the double-walled enclosure  12 . 
     The double-walled enclosure  12  and vented lid  46  are both preferably transparent to let the sun shine in onto the plant. 
     Late in the growing season, the gardener can turn on the first heater  42  and/or second heater  56  again and wrap the trellis  34  with the plastic cover  38 . The gardener can even warm adjacent plants by placing a tarp over the entire gardening device  10  and adjacent plants. The warmth from the first heater  42  and/or second heater  56  is then distributed to all plants under the tarp. 
     The gardener may reuse the gardening device  10  from one growing season to the next. 
     In the drawing and specification, there has been set forth a preferred embodiment of the invention, and although specific terms are employed, these are used in a generic and descriptive sense only and not for purposes of limitation. Changes in the form and the proportion of parts as well as in the substitution of equivalents are contemplated as circumstances may suggest or render expedient without departing from the spirit or scope of the invention as further defined in the following claims.