It is common in Northwest Florida for palms to show signs of nutrient deficiencies. In general our sandy soil is often nutrient poor and available nutrients can easily move out of soils with frequent rainfall. In landscapes where fertilization is occurring, often the wrong types of fertilizer are applied. Fertilizer miss-application actually increases nutrient problems for the palm.
Palms can be deficient in many nutrients but the most common deficiencies we see in landscapes are from inadequate amounts potassium and magnesium. The simple solution would be to purchase a fertilizer labeled for palms to correct the problem. The difficulty is that most easily available fertilizers for palms do not have the correct form of nutrients that are required for the problems. With the exception of nitrogen, all other nutrients are in a quick release form so while the slow release nitrogen lasts for 2-3 months, all other nutrients have been used up. In response, the palm is encouraged to grow by the nitrogen but does not have enough of the other critical nutrients to carry out vital plant functions. What we see is often older leaves that are yellowing, browning, and die off before they should because the plant is pulling any available potassium and magnesium from old fronds to support new growth. Without the application of proper nutrients to the soil, the deficiency can continue until even new fronds are affected or the palm dies.
There is a solution that will help keep your palms healthy and attractive. Make sure you choose a specially designed fertilizer that has all nutrients in slow release form. Look for an analysis such as 8-2-12-4 (Nitrogen-Phosphorus-Potassium-Magnesium). Also read further on the label for Polymer Coated Sulfate of Potash, Magnesium Sulfate (Kieserite), and Chelate (Iron EDTA). These are the forms of nutrients that will be beneficial to your palms.
If you have a mixed landscape where the palms are planted in the lawn, be sure to keep all lawn fertilizers out of the root zone of the palms. Lawn fertilizers do not have the correct forms of nutrients for palms. Remember also that palms roots extend many feet beyond the palm canopy so your ‘no lawn fertilizer zone’ may be past the mulch ring.
The recommendation from the University of Florida is 1.5 pounds of fertilizer over a 100 square foot area. Broadcast this on top of the ground and lightly water after application. In North Florida, you will likely apply the correct palm fertilizer about at least two times in May and end of August or 1st of September. If you are not able to use a palm fertilizer with the correct form of slow release nutrients, it is best not to fertilize palms at all.