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Vegetable Gardening In Containers
Sam Cotner, Extension Horticulturist
If your vegetable gardening is limited by insufficient space or an unsuitable area, consider the possibility of raising fresh, nutritious, homegrown vegetables in containers. A window sill, a patio, a balcony or a doorstep will provide sufficient space for a productive mini-garden. Problems with soil-borne diseases, nematodes or poor soil conditions can be easily overcome by switching to a container garden.
Almost any vegetable that will grow in a typical backyard garden will also do well as a container-grown plant. Vegetables which are ideally suited for growing in containers include tomatoes, peppers, eggplant, green onions, beans, lettuce, squash, radishes and parsley. Pole beans and cucumbers also do well in this type of garden, but they do require considerably more space because of their vining growth habit.
Variety selection is of extreme importance. Most varieties that will do well when planted in a yard garden will also do well in containers. Some varieties of selected vegetables which are ideally suited for these mini-gardens are indicated in Table 1.
Note: For additional information on variety selection, consult your county Extension agent or Extension horticulturist.
Synthetic "soils" are best suited for vegetable container gardening. These mixes may be composed of sawdust, wood chips, peat moss, perlite, vermiculite or almost any other type of media. Regardless of what mixture is used, however, it must be free of disease and weed seeds, hold moisture and nutrients but drain well and be lightweight. Many synthetic "soils" are available from garden centers, or one can be prepared by mixing horticultural grade vermiculite, peat moss, limestone, superphosphate, and garden fertilizer. To 1 bushel each of vermiculite and peat moss, add 10 tablespoons of limestone, 5 tablespoons of 0-20-0 (superphosphate) and 1 cup of garden fertilizer such as 6-12-12 or 5-10-10. Mix the material thoroughly adding a little water to reduce dust. Wet the mix thoroughly prior to seeding or transplanting.
Almost any type of container can be used for growing vegetable plants. For example, try using bushel baskets, drums, gallon cans, tubs or wooden boxes. The size of the container will vary according to the crop selection and space available. Pots from 6 to 10 inches in size are satisfactory for green onion, parsley and herbs. For most vegetable crops such as tomatoes, peppers and eggplant, you will find 5-gallon containers are the most suitable size. They are fairly easy to handle and provide adequate space for root growth.
Regardless of the type or size of container used, adequate drainage is a necessity for successful yields. It is advisable to add about 1 inch of coarse gravel in the bottom of the container to improve drainage. The drain holes are best located along the side of the container, about 1/4 inch to 1/2 inch from the bottom.
Best suited for container culture are vegetables which may be easily transplanted. Transplants may be purchased from local nurseries or can be grown at home. Seeds can also be germinated in a baking pan, plastic tray, pot or even a cardboard milk carton. Fill the container with a good media such as the one previously described, and cover most vegetable seed to a depth of 1/4 inch to 1/2 inch to insure good germination. Another method would be to use peat pellets or peat pots which are available from local nursery supply centers.
The seed should be started in a warm area that receives sufficient sunlight about 4 to 8 weeks prior to the anticipated transplanting date into the final container. Most vegetables should be transplanted into containers when they develop their first two to three true leaves. Transplanting should be done carefully to avoid injury to the young root system. (See Table 2 for information about different kinds of vegetables.)
The easiest way to add fertilizer to plants growing in containers is by preparing a nutrient solution and pouring it over the soil mix. There are many good commercial fertilizer mixes available to make nutrient solutions. If one is utilized, follow the directions on the label. An adequate nutrient solution can be made by dissolving 2 cups of a complete fertilizer such as 10-20-10, 12-24-12 or 8-16-8 in 1 gallon of warm tap water. This solution will be a base solution. From this can be made a growing nutrient which will actually be poured around the plants. To make the growing solution, mix 2 tablespoons of the base solution in 1 gallon of water.
If you use transplants, begin watering with the nutrient solution the day you set them out. If you start with seed, apply only tap water to keep the soil mix moist enough until the seeds germinate and the plants emerge. Then begin using the nutrient solution.
The plants should be watered with the nutrient solution about once a day. While the frequency of watering will vary from one crop to the next, usually once per day is adequate. Should the vegetable make a lot of foliage growth, twice a day may be necessary. Less water will be needed during periods of slow growth.
At least once a week, it is advisable to leach all the unused fertilizer out of the soil mix by watering with tap water. Add sufficient water to the container to cause free drainage from the bottom. This practice will prevent any buildup of injurious materials in the soil mix.
Occasionally, it is a good idea to water with a nutrient solution containing minor elements. Use a water-soluble fertilizer containing iron, zinc, boron and manganese, and follow label directions.
Proper watering is essential for a successful container garden. Generally one watering per day is adequate. However, poor drainage will slowly kill the plants. The mix will become water-logged and plants will die from lack of oxygen. If at all possible, avoid wetting the foliage of plants since wet leaves will encourage plant diseases. Always remember that each watering should be done with the nutrient solution except for the weekly leaching with tap water.
Nearly all vegetable plants will grow better in full sunlight than in shade. However, leafy crops such as lettuce, cabbage, greens, spinach and parsley can tolerate more shade than root crops such as radishes, beets, turnips and onions. The root vegetables can stand more shade than those which bear fruit, such as cucumbers, peppers, tomatoes and eggplant. One advantage to container gardening is mobility. Container gardening makes it possible to position the vegetables in areas where they can receive the best possible growing conditions.
Vegetables grown in containers can be attacked by the various types of insects and diseases that are common to any vegetable garden. Plants should be periodically inspected for the presence of foliage and fruit-feeding insects as well as the occurrence of diseases. Should problems occur, then the timely application of EPA-approved fungicides and insecticides is advised. Contact your local county Extension agent for the latest information on disease and insect control on vegetable plants.
For the greatest amount of enjoyment from a container garden, harvest the vegetables at their peak of maturity when a vegetable's full flavor has developed. This will yield maximum pleasure from the excellent taste of vine-ripened tomatoes, tender green beans and crisp flavorful lettuce.