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Managing Palm Fertilization during “Black-Outs”

One of the 9 Florida Friendly Landscaping principles is “Fertilize Appropriately”.  As a homeowner or landscaper, sometimes it’s difficult to know what that means during fertilizer “black-out” periods. Fertilizer black-out times are when we are forbidden to use fertilizers containing N (Nitrogen) or P (Phosphorus) in the landscape.

What are fertilizer black-out periods?

Ft. Lauderdale recently issued a Nitrogen (N) and Phosphorous (P) black-out for June 1 – September 30, and other cities are also re- evaluating their current regulations about fertilizer.  This change is to protect the waterfronts: our beaches, lakes, and rivers.

Black-out periods also coincide with the summer, when plants are growing quickest and require the most fertilizer to maintain their health.  So, what’s the best way to protect the environment while keeping our palms and ornamentals looking their best?

Nutrient deficiencies are more easily prevented than corrected.

In many non-native palm species that we grow here, it is essential to fertilize because our native soil has serious deficiencies of the nutrients they need.  Some palms will decline rapidly and even die if not fertilized regularly, and it can take years to correct a deficiency once it appears.  If you love your palms and want them to thrive, then you must get on a regular feeding schedule.

Palm nutritional deficiencies cause rapid decline that can take years to correct.

What to feed your palms

It is imperative that 100% of the N (Nitrogen), K (Potassium) and Mg (Magnesium) be in SLOW RELEASE form.  Since our soils are extremely porous, the only way to keep these nutrients in the tree root zone is to provide them in slow release form.  Water soluble fertilizers will quickly leach out during periods of heavy rain and irrigation, wasting money and polluting water.

Look for Palm Special fertilizers having 8N-2P-12K+4Mg with micro-nutrients. Read the label and be sure it states these slow release sources of N (Nitrogen) on the bag: sulfur-coated urea, urea-formaldehyde, resin-coated urea and resin-coated ammonium salts, and follow the recommended application rate, which will depend on the size of the palm or plant bed.

How you apply fertilizer is also important.

Do not concentrate fertilizer in holes, spikes or bands around the trunks of palms.  Spread it uniformly around the area under the canopy.  Nutrient movement is always downward, so only a small portion of the root system will be able to capture the nutrients when applied in concentrated areas.

Handling black-outs is easy!

If your city or county prohibits the application of N (Nitrogen) and P (Phosphorous) during the summer months, you can simply apply complete fertilizers in February, when quicker growth begins, May, right before the black-out and then again in November, before winter begins.  Studies show that if the August application skips the N (Nitrogen) and P (Phosphorous) component as required by law, but still provides the K (Potassium) and Mg (Magnesium), the palm quality is as good as the traditional recommendation of 4 applications of complete fertilizer per year.  (Click here for full details on fertilization.)

Points to remember:
  • Always use only slow release fertilizers on palms
  • Never concentrate fertilizer – apply evenly around the canopy
  • Apply a complete Palm Fertilizer in February, May and November, and only if needed in August, but using formulations without N (Nitrogen) and P (Phosphorous).
Quick tip

While palm special fertilizers are designed with palm trees in mind,  they are also suitable for most other types of plants.  This includes trees, shrubs, fruit trees and even turfgrass. Trials conducted at UF/IFAS FLREC have shown that St. Augustine grass fertilized with palm maintenance fertilizer had quality equal to that produced by a turf fertilizer.

So, keep it simple.

Using palm maintenance formulations on your total landscape simplifies the process and protects palms from over fertilization caused by high N and K turf formulations.  Remember, that tree roots will extend outward and absorb whatever is there.  Turf fertilizer formulations with a high Nitrogen to Potassium ratio will cause palms to grow too rapidly.  This will induce a potassium deficiency which can lead to early decline and even death.

If palms are happy then everybody’s happy!

When it comes to fertilizing your landscape, using a complete slow-release palm fertilizer according to directions can make the task easier.  These palm fertilizers contain all the necessary nutrients to produce lush and healthy growth of all the plants that live with them, even during fertilizer “black-outs”.

Click this link for a handy app!  It shows each county in Florida and each jurisdiction’s requirements.  Remember, it’s YOUR responsibility to know the laws in each city and county you are working in.


4 Comments on “Managing Palm Fertilization during “Black-Outs”

  1. Very nice article! Can you suggest trade names or where to buy the summer formulation that contains no N or P?

    • Thank you! You can try Lesco for the formulation. However, perhaps you can forgo the fertilization during the black-out period?

  2. Great article Donna. Makes sense not to limit fertilizers in the summer months.

    Do you know of any other Cities that have implemented this? With the recent fish kills in Biscayne Bay, Miami and Miami Beach need to get on board!

    • Thank you, Brian. Yes, they do need to get on board. This is one thing we can do to help mitigate this issue of deteriorating water quality.