Environmental Control with Container Gardening

by Elmer Krehbiel, Master Gardener
January 30, 2004

Containers allow gardeners to control the environment, that is, the soil (potting mix), moisture, location (relative to sunlight and wind), temperature, and weed prevention.

Plants have been grown indoors and out in window boxes in small containers for hundreds of years. Much larger containers have been used for in-door and/or out-door landscaping residents, businesses, and malls for many years.

Landscape and vegetable gardening in containers is growing in popularity. Containers are useful for gardeners with limited space, to provide special features or flexibility in the landscape and obtain maximum production from flower and/or vegetable plants. Special flowers and/ or vegetables may be grown each spring, summer, autumn, and winter season.

Containers are suitable to grow flowers, vegetables, herbs, small to medium size shrubs or dwarf trees.

The most efficient containers have a water reservoir in the bottom with an overflow hole and a cover over the potting mix and a wick into the water. They do not require additional water as often as others.

The containers may be placed up on other structures or brackets or hung from beams so they are more convenient for the gardeners to work with the plants and protect them from animals. During the summer months in this area, the soil may be considerably hotter than the air temperatures. Then the containers need to be placed on plastic pipes or other material that will not transfer all of that heat into the potting mix. Most plants that we grow in this area are stressed when the soil becomes hot.

Containers may be purchased or built for special needs. Garden supply centers have traditional units, and some with special features and designs. Other suitable types with drainage holes are: buckets, baskets, 30-or 55-gallon drums, cans, tubs, sacks, boxes, half-barrels, etc. Another idea is to hang a bucket from a high hook or beam with a tomato plant growing down out of the bottom.

Plants require suitable moisture, air, nutrients, light and temperature. Many plant species needs at least eight hours of sunlight each day. Plants in containers require more water and fertilizer, than those in the beds or plots.

The size for vegetable plants of beets, carrots, Swiss chard, lettuce, onions and radishes should be at least a 1-gallon container; 2-gallons for beans, mustard and turnips; 3-gallons for peppers and 5-gallons or more for all larger plants according to their expected mature root system.

The containers may be moved for protection from the cold, heat and strong wind. They may be moved into more or less sunlight.

Container gardening can prevent some soil problems. Soils for container plants must have different properties than those in the yard. The potting mix used for container gardening has a much greater effect on plant growth than the container does. Potting mix is best for container gardening and may be obtained from local garden centers or mixed according to a successful formula.

Potting mix should drain well, hold moisture and nutrients, be weed and disease free, be lightweight and contain no yard soil. It should be soaked completely before setting any plants or seeding.

Smaller mature size of flower, shrub and vegetable varieties are more desirable to grow and maintain in containers.

It is best to start with healthy transplants, rather than sowing seeds. Most flowers and vegetables should be transplanted when they develop their first two or three true leaves. Do not touch the hairs on the stem of small plants.

Fertilizers should be water-soluble to avoid accumulation of salts in the container and applied each week, during the peak-growing season. If regular balanced fertilizers are used and the containers have drain holes, leach out unused fertilizer about once each week by applying sufficient water only to cause drainage.

Rainwater is the best source of moisture. When leaves turn yellow and fall off, the plant needed more water several days before that occurred. If the plants are over-watered, the edges of the leaves turn brown. If the containers are too large, it is easy to over-water the plants. Insects and diseases may be easier to control.

Beans, corn, cucumbers, eggplants, melons, peppers, squash, and tomatoes require full sunlight. Beets, carrots, Cole crops, Swiss chard, lettuce, mustard, onions, radishes and turnips require morning sunlight and some afternoon shade during the hot days of summer. All fall crops require full sunlight.

Container gardening is a wise choice for apartment dwellers, a highly mobile society and adding versatility to your gardens. However, container gardening requires better management to develop maximum production.

More on Container Gardening

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Dr. Elmer Krehbiel is the former President of Keep Brazos Beautiful. See his column in The Eagle.