Do Grow Boxes Work Well?

How They Work

• Grow boxes are not self-watering as often described. They are more accurately termed sub-irrigated. Grow boxes are water-tight containers with a water reservoir at the bottom that only needs to be filled every few days. The reservoir has an overflow to prevent overfilling. The plant roots are held above the water level to keep them aired; there is an arrangement to wick the water up into the growing medium. Slow-release fertilizer is added to the planting medium initially, enough for one growing season. A cover helps retain moisture and prevent weeds.

  The system provides maximum amounts of water and fertilizer to plants, which utilize them for fast growth. Grow boxes are hard to move once in place and filled; site them in a sunny location, they can be put on decks, patios and balconies. Well-made grow boxes are long lasting and can be reused year after year.

What Does Best In A Grow Box

• Tomatoes, cucumbers, squash, okra, corn, eggplant, peppers, cabbage, cauliflower, peas, salad, chard, melons and strawberries are among the most popular vegetables and fruit grown in grow boxes. All these are fast-growing annuals capable of making lush fruit and greenery if given sufficient sun, water and fertilizer. There are charts for how many of each plant should be in each box: large bushes like tomatoes are limited to two per grow box, whereas plants such as peas and okra which like crowding can be grown at 20 per box.

  It is less frequently reported, but you can also use grow boxes for water-loving flowering plants.

What Does Not Work

• Grow boxes are not good for desert plants or anything that prefers dry marginal soils. They do not work well for plants which tend to bolt, like radishes. Beware reusing the potting soil too many seasons in a row; each season needs new fertilizer.

Make Your Own Grow Boxes

• There are many articles about making your own affordable grow boxes. Essentially you have to replicate the arrangement for the water reservoir, soil containment and water wicking. Be careful to ensure plant roots get air and don't stay permanently damp. Plastic crates, buckets and mortar boxes are popular containers, using PVC pipe for the water feed.