Plants need potassium for strong stems and roots, but don't expect the Florida "soil" to help.
By JOHN A. STARNES JR., Special to the Times
Published May 10, 2003
Want to make a Florida gardener laugh? Refer to our sand as soil. The near absence of organic matter and vital nutrients, the surplus of nematodes, the excessive acidity inland and the alkalinity along the coast can turn the healthiest plants and trees into weaklings.
Potassium is one of the three main nutrients that plants need. When reading fertilizer analysis such as 10-2-6, the first number is nitrogen, the second phosphorus and the third potassium. Potassium helps plants build strong stems and roots. It also plays a role in fruit formation and plant metabolism, and it helps plants build resistance to disease and freezes. The little that is in our soil rinses out during heavy rain and irrigation. Potassium supplements are hard to come by, so the roots of our plants, trees and lawns struggle each year.
Gardeners comfortable with chemical feedings can use muriate of potash. The problem is, it's sold to the public in only small bags. Plus, it's high in chlorine, which is abundant in our sand, and too much is harmful to plants.
A classic potassium source is white hardwood ash from a fireplace or campfire. Oak leaves work as a slow release source of potassium in garden beds, but by their nature, they are useless on lawns.
Rosarians have long relied on the natural mineral sold as Sul-Po-Mag to provide potassium, plus the magnesium and sulfur lacking in sandy soil.
Feed stores supplied by the Manna Pro Corp. carry this mineral as a natural livestock supplement under the name DynaMate. It comes in 50-pound bags. A 5,000-square-foot front yard would relish this easy-to-apply potassium source: two bags in the spring, two bags in the fall.
Sprinkle it by hand on veggie, flower and rose gardens (apply it about as heavily as you'd sprinkle Parmesan cheese on spaghetti). It won't burn your hands or plants and is safe for pets. Use a broadcast spreader to treat your grass (Bahia, St. Augustine or Bermuda) twice a year. Once a good rain or sprinkling begins dissolving it into your plants' root zones, they will get the potassium they need. Bulbous plants (crinums, amaryllis, onions, etc.), root crops (potatoes, sweet potatoes, true yams), citrus, palms, cycads, shrubs, perennials and annuals will benefit as the season progresses.
Not all feed stores are supplied by Manna Pro, so call your favorite one to be sure it has the mineral on hand or will order several bags for you.
- John A. Starnes Jr., born in Key West, is an avid organic gardener and rosarian who studies, collects, cultivates and hybridizes roses for the diverse regions of Florida and Colorado. He can be reached at his new e-mail address: JohnAStarnes@aol.com
