Tips to improve your garden this summer

CLEMSON - The best approach to fertilizing a garden is to follow the soil test recommendation. Information on soil testing is available in the fact sheet HGIC 1652, Soil Testing. Spread lime and other fertilizer evenly and uniformly over the entire garden area. Gardeners who prefer to add fertilizer to the row should place it at least 3 inches below and 2 to 3 inches to the side of the seed position. Closer placement may result in fertilizer burn and poor stands.

If the soil was tested last year but not tested for the current season, apply the fertilizer at the same rate as the previous year. Do not apply lime until another test is taken. Poor growth and nutrient deficiencies may occur with too much lime.

Applying limestone when needed according to soil test results will benefit the garden in two ways. It eliminates some acid in the soil and allows plant nutrients to become more available to plants. Limestone is also a form of fertilizer because it contains calcium, a necessary nutrient for plant growth. Dolomitic limestone also contains magnesium, which is essential for plant growth. Lime effectiveness is increased by grinding, and the smaller the particles, the faster it will become effective in reducing acid. Pulverized limestone is the most effective form of agricultural limestone. Other types of lime are sold but must be used at differing rates. All recommendations are based on the use of agricultural limestone.

If a recent soil test is not available, apply 5-10-10 at 30 pounds of fertilizer per 1000 square feet of garden. This initial preplant application will normally supply all of the phosphorous and potash needed by most garden vegetables. Nitrogen requirements vary from crop to crop, and heavy rainfall or sandy soil may cause nitrogen to leach from the soil. For these reasons additional nitrogen may be required.

The application of fertilizer after plants are established is called sidedressing, and some plants respond more than others. This application should contain primarily nitrogen. The first sidedressing application should be applied four weeks after planting using either 7 pounds of calcium nitrate per 1000 square feet or 2 pounds per 100 feet of row. Apply in a band along one side of the row and about 4 to 6 inches from the plants, depending on the plant size. An additional application of general fertilizer (the same as you applied preplant) will be beneficial after heavy (3 inches or more) rains.

Other commonly available sidedressing fertilizers and rates of application per 100 feet of row are: ammonium sulfate with urea (34% nitrogen) at 1 pound, or 10-10-10 (10% nitrogen) at 3 pounds. These application rates will provide approximately 0.3 pounds of actual nitrogen per 100 feet of row.

A corn or tomato crop will need typically 3 sidedressing applications per season. Sweet potatoes and greens will require typically 2 applications per season, while beans and squash will require typically one application per season. If liquid fertilizers are used, such as 20-20-20 or 15-30-15, then mix according to the label and apply every 2 weeks. Other sources of nitrogen may include synthetic materials such as 5-10-10 or urea, or natural materials such as bloodmeal or cottonseed meal.

For answers to your gardening, pest and food safety questions, visit the Clemson Extension Home & Garden Information Center website at http://www.hgic.clemson.edu or call us toll-free at 1-888-656-9988.