Gardening: Tips for container gardening

April 26, 2013 

Q. For planting tomatoes, what is the optimum width and depth of the container? Which is more important, width or depth?

-- K.K. of Collinsville

Q. I am planning on making container vegetable gardens. How should I go about doing it?

-- L. D. of Columbia

Q. What makes good containers for raising flowering plants and what kind of soil should I use?

-- W. D. of Belleville

A. This year, there seems to be a great interest in container gardening. The container can be almost anything that can hold together for a year or more, from an old shoe or boot to a rusty bucket or sturdy wooden box and, of course, the decorative containers that can be found in garden centers.

Every kind of plant can be grown in a container also but modifications are necessary for woody plants like trees and shrubs.

In answer to the first question, the depth of the container is most important. The minimum depth should be at least 8 inches. Deeper is better. The depth gives more room for the roots to grow and absorb water and liquefied fertilizer. The depth will allow for cooler conditions the deeper the media, and roots are more used to cooler temperatures than the upper parts of the plant exposed to air.

The width is also important. The larger the surface area, the better water can soak into the growing media. For tomato plants, a 1-foot-square area should be the minimum size. This same rule usually works for flowering plants to be grown in a container. But the container can be shallower for lower growing dwarf plants that are only a few inches tall and for vining plants.

Media is an important consideration as well. Media needs to be loose and fluffy to be able absorb and hold water in the root zone. Most contains a decomposed peat moss, which is dark black. Avoid including native soils. They will add weight to hold the contained upright, but placing inert rocks in the bottom can serve the same purpose.

Make sure the container has drainage holes so the roots do not drown from water backing upward in the container.

Also be ready to fertilize container plants on a two-week schedule as the container media does not contain many nutrients for plant growth. Remember the first number on the fertilizer indicates nitrogen, which will promote stem and leaf growth, important when the container plants are quite small.

The second number on a fertilizer container is the percent of phosphorous. It is necessary for root growth, flower production and later for the development of fruit.

The third number indicates the amount of potassium or potash, which is necessary to help your plant avoid stress. Fertilizer needs to be applied in liquid form so the plant's roots can absorb it immediately. But do not apply at the recommended strength. Apply at half the recommended rate because, once the plant collects these nutrients, it does not have an filtering "kidney" to excrete the excess. Too much water kills more plants grown in containers but over-fertilizing comes in a close second.

Do it now

MULCH: Mulch everything when you plant it. This can save time and energy so you do not have to weed as much.

WATER: Water in the very early morning so the sun can dry the water droplets off the foliage and prevent diseases from developing on the plants.

PESTS: After all the recent rain, be ready to control snails and slugs. A saucer of beer does a great job.

Charles Giedeman is a local contributing writer. Send your gardening questions to Lifestyle Editor Pat Kuhl, Belleville News-Democrat, P.O. Box 427, 120 S. Illinois St., Belleville, IL 62222-0427.

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