Controlling Garden Fertility with Sidedress

The fertilizer element most needed and most often applied by this method is nitrogen. The need and frequency of sidedressing depends somewhat on the soil type, fertilizer used and vegetables grown. Sidedressing with nitrogen fertilizer becomes most important in loose, sandy soils where a soluble fertilizer element such a nitrogen is easily leached away during watering or heavy rains.

Slow-release fertilizers applied at planting time spread fertility release, and reduce the frequency of sidedressing. Some plants, such as corn and tomatoes, are heavy feeders, and need several sidedressings during the growing season. Other plants, such as sweet potatoes and turnips, normally do not need sidedressing and it may reduce yields. Sidedressing is usually done with fertilizers containing high levels of nitrogen. Such materials include ammonium nitrate, urea or ammonium sulfate.

Complete garden fertilizers may be used, but the main plant response normally comes from the nitrogen they supply. Nitrogen is soluble, and moves easily down into the root zone after watering or rainfall. Both ammonium nitrate or urea may be used as a sidedressing.

Apply the sidedressing in a relatively wide band or shallow trench at least 3 to 4 inches away from the row or individual plant. Although sidedressing may be done on only one side of a row, there is less chance of root burn from the fertilizer if half the amount is applied on each side of the row. Widely spaced plants such as tomato, cucumber or squash may be fertilized by placing a circular band around the plant. Tomatoes respond well to nitrogen sidedressings; however, too much nitrogen early in the season can delay production.

Apply the first sidedressing by tomatoes about one to two weeks before the first tomato ripens. Follow this with another sidedressing about a month later and, if necessary, again in another 4 to 5 weeks. Sweet corn is also a heavy user of nitrogen and normally needs a sidedressing when plants are about 8 to 10 inches all and again about a week after tassels appear. Keep fertilizer off the leaves when applying, and never use more than recommended. If in doubt, use a little less.

Water the garden after application to wash off any fertilizer that may have landed on leaves, and also to start the fertilizer into solution and into action.

The Vegetable Gardener's Bible, by Edward C. Smith.