By ROBIN ROBINSON Key West Garden Club
Nitrogen, phosphorus and potassium -- N, P, K on the periodic table of elements -- are the three that put fear in the hearts of many a gardener. The questions pop up like weeds. What kind? What brand? Is this enough? Too much? Where do I put it? Will it make my plant flower? Burn it? How long does it last?
So here are a few good words about fertilizer, which contain all three elements and should be replenished every six months. Native plants do not need fertilizer, but they do better with it. Exotics definitely need its help.
It is important to choose a fertilizer that works in the Florida Keys' alkaline soil. The Key West Garden Club uses Palm Special (8-2-12) by Atlantic-Florida East Coast Fertilizer & Chemical. This is granulated fertilizer specially formulated for South Florida plants. Besides the three main elements, it has 10.8 percent potash, 4.31 percent sulfur, 4 percent magnesium, 0.99 percent manganese, 0.14 percent iron, and 0.05 percent of each copper and zinc. It is coated with sulfur to allow it to release slowly into the ground. The more it rains, the more fertilizer is dissolved, but it generally lasts six months.
Miracle Grow is good for instantaneous feeding, but it will not bind to our limestone. Instead, it goes directly into our groundwater and then into the ocean. There is a special fruit tree fertilizer for trees such as mango, avocado and lime. Bananas need Banana Special Fertilizer.
Don't hesitate to use your coffee grounds and tea leaves for bananas, roses, ixora, hibiscus and most exotics that like a more acid soil. Plants here also like plant tabs and will grow faster with them.
If you would like your plants to bloom profusely, add potassium to the soil. Choose a fertilizer with a high last number.
Lack of iron (Fe) is often a problem here in the Keys. If the plant's leaves are yellow and anemic looking, add chelated iron to the soil. A powdered product named Sequestrene can be absorbed and works well. Work in old clothes, as it stains everything it touches yellow.
Of course, yellow leaves could also mean that the roots of the plant have been damaged by too much salt in the soil. For potted plants, SUPERthrive will dissolve salts.
Applying fertilizer is another learned skill. Do not simply throw it at the roots of the trees. Most roots in the Keys are shallow and wide. Feeder roots will often be within 2 inches of the top of the soil. Fertilizer should be broadcast under the entire canopy of the tree.
Instead of using your hands or a scoop that may result in uneven application, which would burn the roots, put the fertilizer into a plastic pot with holes in the bottom and swing the pot evenly over the area to be fertilized. Mulching is another form of fertilizing. Buying invasive melaleuca mulch instead of eucalyptus mulch gives the gardener a double whammy. First the mulch is good for retaining moisture and nutrients in the soil; and second, harvesting the invasive melaleuca is part of its statewide eradication. Save a eucalyptus tree. Cyprus mulch does not rot and return nutrients to the soil, but it looks nice.
Putting pea rock on the ground does nothing to help the soil. It simply raises the pH alkalinity level even higher. If it is possible, it is best practice to leave the fallen leaves and they will soon turn your soil into rich composted black soil.
So if you want to "perti-lize" your garden, fertilize.
•The Key West Garden Club will have a fertilizer party at 9 a.m. Monday. Join in to spread it around. Club members may buy fertilizer for their own gardens directly from the club on Monday mornings.
•The club welcomes volunteers to pull weeds, learn to propagate plants and play in the sandy soil at the West Martello Tower from 9 a.m. to noon on Mondays.
Key West Garden Club Master Gardener Robin Robinson was a columnist at the Chicago Daily News and syndicated with Princeton Features. Her books,. "Plants of Paradise" and "Roots, Rocks and Rain: Native Trees of the Florida Keys," can be found at the Key West Garden Club and on Amazon.com. Visit www.sorapublishing.com for more information. This column is part of a series developed by the Key West Garden Club. Visit www.keywestgardenclub.com for more information.