By BJ Jarvis
Florida gardeners are in love with a few plant groups and palms are near the top of many gardeners’ “must have” list. Unfortunately most landscape palms suffer from improper nutrition.
These expensive and cornerstone components of our landscape need to have their nutritional deficiencies accurately identified and met. If not, the result is a super-stressed plant or worse, death. Let’s look at four common nutrient issues and how to resolve them.
Symptoms on older leaves
While turf likes nitrogen, it is rarely a palm deficiency. On the other hand, potassium, the last number on a fertilizer bag, is one of the most widespread challenges. Symptoms are often confused with diseases, appearing as small yellow spots in the leaves. In severe cases, leaflets become dried and frazzled. The midrib will remain green and usually appears on older fronds.
Magnesium is also commonly in short supply for palms. Canary Island palms are especially prone, appearing as a yellow band along the margin of older leaves. Thankfully, a magnesium shortage rarely kills landscape palms.
Symptoms on new leaves
Manganese can be identified on damage on new leaves characterized as frizzle top. New spear leaves are weak, withered and often misshapen. Queen palms are especially prone to manganese deficiency.
Boron deficiency appears initially as bent leafs progressing to a zipper-like or accordion pleated leaf. Queen palms are especially affected and in more severe cases, the entire plant will grow to one side.
So how does the gardener address this confusing and extensive array of palm nutritional deficiencies? This is one of the few times I recommend a special fertilizer to assure proper nutrition. Slow release palm fertilizer should be applied uniformly over the soil surface, not just in a small band that isolates fertilizer to about 10 percent of the roots.
The best palm fertilizer is one that has a nutritional complement of 8-2-12+4Mg (magnesium) plus minor nutrients. Although minor nutrients are needed in only small quantities, they are vital to plant health. Prilled kieserite is the best formulation for the 4 percent magnesium.
Palm fertilizer should be applied for a full 25-foot radius around palms, even if that extends into the rest of the plantings or grassy areas. Never use turf fertilizer around palms, as the high nitrogen adversely affects the other nutrients. With a palm fertilizer, grasses and other landscape plants are just as happy. But palms are never happy with turf fertilizer.
Deficient palms will appreciate fertilization a couple times per year, usually in April, June and early October. Remember, no fertilizer is better than using the wrong fertilizer.
One reason palms are expensive is they grow slowly, which means their health improves slowly too. Putting on an average of one new leaf per month, you must be patient to see improved palm health.
Keeping palms properly nourished will pay back huge dividends in the long run for these stately pillars of our landscapes.
For more information on palms nutrition, visit the University of Florida’s, http://edis.ifas.ufl.edu/pdffiles/EP/EP26100.pdf or contact the Pasco Extension office.
—BJ Jarvis is Director and Horticulture Agent for Pasco Cooperative Extension, a partnership between the University of Florida, USDA and county government. She can be reached at . Visit Extension’s website at www.pasco.ifas.ufl.edu/gardening for more information.