A grow box is a unit used to grow plants and vegetables indoors or in small spaces. The term can be used to mean simply a covered base for retaining water and preventing weeds (see, for example, the homemade tomato-growing units pictured in this writeup from Texas A&M’s Agrilife Extension).
However, more full-fledged grow boxes are complete enclosures that provide the gardener with the ability to regulate temperature, light, water and nutrients for optimal growth. These units are also called grow closets or grow cabinets.
Like window farms and kitchen gardens, grow boxes make it possible to grow vegetables conveniently and in otherwise-challenging climates and spaces.
Main elements of an enclosed grow box
In addition to the frame and walls, an enclosed grow box will typically include:
-- A light fixture. HID (high intensity discharge) lamps are commonly used as grow lights, and LED and fluorescent lights are also options. Different types of light are optimal for different plants and different stages of growth. According to Interior Gardens in Minneapolis, MN, metal halide (MH) lights are preferable for vegetative plant growth, whereas High Pressure Sodium (HPS) lights are more suitable for fruiting and flowering plants. Both MH and HPS bulbs are forms of HID lighting.
-- A fan and air filter for clean ventilation. This is important for letting excess heat out of the system.
-- Optionally, a water retention/circulation/filtering system. Some grow boxes are hydroponic; by some industry estimates, a hydroponic system (which recycles water) may use as little as one quarter of the water consumed in conventional soil-based systems, says Nate Lipton, founder of Growers House in Tucson, AZ.
-- Insulation to help manage temperature and to protect the construction itself from the effects of moist air in the box. The inside of the box should be lined with an easy-to-clean material, and reflective insulation or liner will help maximize lighting efficiency.
Building or buying a grow box
There are many commercially available grow boxes from small capacity to large. A scan of various websites finds prices ranging from small units under $33 to more than $3,000 for a high-end system. It is also easy to find instructions online for building your own system – do-it-yourself builders will need to know about required space, wattage, and nutrients appropriate for their intended plants. Lipton notes that “the market isn't completely established and the end users tend to be DIYers, so there are often new products and techniques…showing up all over the web.” Effective techniques developed by enthusiasts eventually make their way into commercial products.
(Note: Because of legal and privacy concerns, marijuana growers often use grow boxes, so a good deal of online information is on pro-pot websites, which may also use the term “stealth box”.)