Contact: Diane Relf, Extension Specialist, Environmental Horticulture
Posted April 1997
Home gardeners are discovering the joy of growing flowers and vegetables in bags of potting soil. Soil mix, in a plastic bag, creates a self-contained planter. Planted, all by itself, it becomes a flower garden, which can be fully covered with flowers from spring until fall. Portable, if placed on a wheeled dolly, it can be moved to follow the sun. It can be rolled to the deck or patio for its color to be shown off at parties, or enjoyed indoors as the sun goes down.
Widely used in Europe, large numbers of soil bags are used by commercial, greenhouse growers for producing tomatoes and cucumbers, as well as flowers. The idea is now beginning to catch on here. Growing in bags takes the idea of container gardening to its ultimate simplicity.
Bagged soil mixes come in different sizes usually containing 4 quarts, 8 quarts, 16 quarts, or 40 quarts of lightweight media. Even the largest size, planted and fully moistened is light enough to move from place to place if it is placed on a sturdy, movable base.
Soilless mixes based on peat and vermiculite provide an ideal combination of moisture-holding capacity and the necessary aeration to let roots breath. Soilless media is free of disease organisms and weed seeds providing an ideal growing environment for flowers or vegetables.
How to Grow in a Bag: Make a hole in the bag of potting media large enough to insert a hose and water slowly, but thoroughly. Fill the bag with water until it resembles a balloon. Let it sit until the water thoroughly permeates the soil mix. Check to make sure that all media is uniformly moist before you start planting. If not, water again. Add fertilizer according to the manufacturer's recommendations. Many gardeners start with a slow-release fertilizer and supplement with a soluble fertilizer.
Compact plants, such as 'Patio' tomato, will grow well in a bag with no support. But taller-growing plants, such as indeterminate varieties of tomatoes, will need staking or caging to keep them from sprawling. Since the bag of media does not provide sufficient depth for supports, stakes or cages are usually secured to a board or dolly under the bag.
Planting is easy. Cut holes in the bag equal to the number of plants. Plant growth is vigorous but if you want full coverage fast, plant closely together. The dimensions of a 16-quart bag are approximately 20 x 13-inches. For instant coverage of flowering plants, space them on four-inch centers. For slower coverage, space plants up to six inches apart on center. Be sure to plant near the edges so foliage hides the edges of the bag quickly. A plastic bag becomes totally covered with foliage, in most cases, within weeks after planting, forming an invisible container, a veritable mound of flowers or vegetables.
At season's end the potting soil mix is reusable in other containers, or for improving the tilth of a regular garden plot or flower bed. If the plastic bag has been shaded from the sun, it may be able to be used the next season as a planting bag, but bags in sunlight usually deteriorate after one growing season.
(Prepared by Virginia Nathan, Extension Technician, Consumer Horticulture, Virginia Tech, Blacksburg, VA 24061-0327.)
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