Q.: I heard that collards and turnip greens are heavy feeders. What does that mean, and what do I feed them?
A.: Vegetables are classified into three groups based on the amount of fertilizer they need – heavy, medium and light. Heavy feeders are hungry plants, and like growing children, they need lots of food to keep them healthy. They require four to five pounds of 10-10-10 or equivalent fertilizer per 100 square feet. One pint of fertilizer will weigh about one pound.
Usually, about one half of the fertilizer is broadcast or spread and tilled into the soil before planting. Then about half way through the crop cycle (8 to 10 weeks) side dress with the remaining fertilizer. Side dressing is just what it sounds like. Place the fertilizer about four inches from the plant and mix it into the soil. Do not let fertilizer touch the plant. If it gets too close to the plant, it will burn the roots and kill it.
In planting a vegetable garden, you should use plants that are mutually compatible. One year ,you will plant heavy feeding vegetables near each other in rows or in your raised beds. The next year, you will swap the plants to medium or light feeders. This changing of the types of feeders from one year to the next is crop rotation, just as is switching from one family of plants to another helps to prevent diseases. It also makes it easier to maintain your garden and apply fertilizer to larger sections of the garden at once.
Some examples of heavy feeding vegetables are the brassica family: cabbage, broccoli, kale, cauliflower, spinach, Brussels sprouts, turnip greens and collards. Also included are leeks, onions, squash, sweet corn, tomatoes, and peppers.
Most other vegetables are medium feeders: carrots, beets, radishes, turnips, rutabagas, snap beans, carrots, cucumber, eggplant, peas, melons, okra, and lettuce. Medium feeders require 2.5 to 3.5 pounds of 10-10-10 fertilizer per 100 square feet.
Most herbs are light feeders. Vegetables that are light feeders are asparagus, sweet potato and Southern peas, such as purple hull, crowder, lady, and field. Light feeders require about 1.5 pounds of 10-10-10 fertilizer per 100 square feet.
You may tire of hearing this piece of advice from Master Gardeners, but it is so very important to test your soil before planting your crops. Since all vegetables do not need the same amount of fertilizer, soil testing can eliminate guesswork. Also, the soil test evaluates the pH of your soil. Lime may be needed to make the fertilizer available to the plants. On the other hand, some nutrients may become too available and become toxic to the plants. Take soil samples to the UGA Cooperative Extension, Carroll County, 900 Newnan Rd., Carrollton, GA 30117, or for more information call 770-836-8546.