Selecting Good Fertilizers for Palms
Summer is coming soon; roots and palm fronds will grow fast! Are you sure that you are applying the correct palm fertilizers? The latest fertilizer recommendation from University of Florida is 8 – 2 – 12 + 4 Mg at the rate of 1.5 lbs. of fertilizer per 100 sq. ft. of palm canopy area. Lately, various fertilizers with the same formulation have appeared in the marked. Which one is the best? Based on Dr. Broschat and Dr. Elliott explanation (UF palm expert specialists and retired professors) a brief justification of why some are good or bad are provided:
Fertilizer Labels A : Is a good fertilizers to use for palms, as they include 100% control-release sources of N, K and Mg. All of the K is present as polymer coated sulfate of potash. All of the Mg is present as magnesium sulfate in the form of kieserite.
Fertilizer Label B: This fertilizer is not acceptable to use for palms because not all of the K is control-release and none of the Mg is control-release. They have included “sulfate of potash-magnesia”, which is 100% water-soluble. So, when the landscape is irrigated or when we do receive our first good summer rain, the Mg will quickly leach and about half of the K will also quickly leach, creating an imbalance in availability of K to Mg and in N to K. This will lead to an increase in both K and Mg deficiencies. The other problem with this fertilizer is that it contains iron oxide and manganese oxides, which are not good sources of Fe and Mn in neutral or alkaline soils
Fertilizer Label C: This fertilizer is really bad! The only control-release nutrient is the N, as polymer coated urea. The K and Mg are all 100% water-soluble sources, which are highly leachable. The other problem is the micronutrients (except boron) are sucrates, which are nothing more than oxides with molasses – i.e., they are not good sources of micronutrients. This fertilizer should not be used on palms!
Remember: Bad fertilizers are a waste of money and could cause pollution. It is better to follow Dr. Broschat recommendation: If you can’t fertilizer your palms correctly, you are better off not fertilizing at all!
For a thorough explanation of palm fertilizers, see EDIS publication: Not All Landscape Palm Fertilizers are the same: http://edis.ifas.ufl.edu/ep516.