All plants must have food for growth. Once plants use up the food stored in the seed, they must obtain sufficient amounts from the soil or other medium in which they are growing. Generally, plant food is in the form of commercial fertilizer or manures. The fertilizer recommended for most garden soils is called a mixed fertilizer. Both dry and liquid forms are effective. If must be placed in the soil where plant roots can reach it. Spraying fertilizer on the leaves is not suggested except for correcting micronutrient deficiencies.
Florida’s sandy soils are notoriously infertile. This is a major problem for commercial farmers and backyard gardeners alike. You can improve the fertility of your garden soil with animal manures and other kinds of organic matter. But, in most situations, you also need to add a commercial fertilizer.
Plants need a variety of nutrients. But the major elements you must supply are nitrogen, phosphorus, and potassium. These chemicals are always listed in that order on the fertilizer tag. The tag also shows the quantity of each major element in the mix. For example, a 100 pound bag of 8-8-8 fertilizer contains 8 pounds of a nitrogen compound, 8 pounds of phosphorus, in the form of phosphoric acid, and 8 pounds of a potassium compound, call potash.
The type and amount of fertilizer you need will depend largely on the kind of soil in your garden. Your objective is to add only those nutrients that your soil doesn’t already contain in adequate amounts. You should remember that too much fertilizer can be as bad as too little. Of course, if you apply too little, your garden will be unproductive. But, if you add too much, you’ll waste money, and you may even injure your crops.
In general an 8-8-8 or 10-10-10 fertilizer is best for sandy soils. For sandy soils, and other soils with low nitrogen content you’ll need from 2 to 5 pounds of a common balanced analysis fertilizer for every 100 square feet of garden. On organic soils, you’ll need one or two pounds per 100 square feet. If the soil in your garden isn’t typical of either of these common types, you should have your soil analyzed to determine the best kind of fertilizer for your particular needs.
You should divide the amount of fertilizer called for into two or three applications. About half should be broadcast over the entire garden a week or two before planting. One fourth of the total amount needed should be applied in shallow furrows on both sides of the seed rows at planting time. This procedure is called banding. The furrows should be about six inches apart, and only two or three inches deep. Spread the fertilizer evenly in the furrows, and then fill them with soil. About three weeks after the crops comes up, side dress with the last one fourth of the total amount of 8-8-8 or 10-10-10 needed per 50 linear feet of row the rest should be applied in two side dressings; three weeks apart after the crops are planted from seeds are transplants. The two side dressings should be placed in a bed in small furrows about 3 inches from the plants to prevent burning.
Analysis, amount, timing, and application method are all key factors in proper vegetable garden fertilization. If in doubt about any of these, check with your garden center or County Extension office.
For more information on garden fertilization contact the Gulf County Extension Service at 639-3200 or visit our website: http://gulf.ifas.ufl.edu or www.http://edis.ifas.ufl.edu and see Publication SP 103 and HS 505.