Planting palms in the landscape is a common practice for homeowners who want to create a more tropical landscape here in Northeast Florida. While one may think of a palm as a tree, it is actually more closely related to grasses and bamboos. While palms may look like a tree, their care and maintenance is a lot more intensive.

One difference in the care of palms is fertilization. A typical shade tree, once established, rarely needs to be fertilized. Palms, on the other hand, need to be fertilized four times a year. Most common palm nutrient deficiencies can be prevented and corrected with proper palm fertilization. The most widespread nutrient deficiency in palms is potassium deficiency. Potassium deficiency symptoms can vary depending on the species of palm but always can be seen on the oldest leaves. The symptoms usually include the deaths of the frond tips. This causes the lower leaves to look brown and tattered. Unfortunately, once a palm leaf is symptomatic, it will be symptomatic until it dies or is removed. However, once the deficiency is corrected, the new leaves that emerge will look better.

The type of fertilizer is also important. Fertilizing a palm with the wrong kind of fertilizer such as high-nitrogen turf fertilizers can quicken their decline. Finding the correct palm fertilizer can be tricky. There are a few important details. First, the analysis on the bag of fertilizer should be 8-2-12 +4mg. This means that the fertilizer should contain 8 percent nitrogen, 2 percent phosphorus, 12 percent potassium and 4 percent magnesium. Second, not all palm fertilizers with these numbers are created equal. University of Florida research has shown that the nitrogen (N), potassium (K), and magnesium (Mg) should come from “controlled-release” sources. This means that they will take longer to dissolve and be available to the palm for a longer period of time. If they are not in a controlled-release form, they will wash down into the soil with rainfall and not be available to the palm in the required ratio, creating a nutrient deficiency. To determine if a nutrient is slow-releasem read the “guaranteed analysis” section of the fertilizer label. It is usually on the side or back of the fertilizer bag. The amount of palm fertilizer added to the landscape should be 1.5 pounds of fertilizer per 100 square feet of area treated; noting that palm roots can go out 30-40 feet from the tree.

There is one caveat to this fertilization regime. If the palm is surrounded by turf that is routinely fertilized with high-nitrogen fertilizer, then the recommendation is to apply polymer-coated potassium sulfate (0-0-16) in addition to the turf fertilizer to adjust the ratio of nutrients given to the tree.

The other important palm maintenance task is pruning. Judging by the palm pruning being performed in our landscapes, you would think that pruning palms to a few fronds sticking out of the top of the tree is the right thing to do. This type of pruning is far from correct. In fact, it is actually harmful to the tree.

Some of the negative outcomes of over-pruning palms are:

• Reduction in the amount of food produced by the leaves, causing the tree to get skinnier and skinnier as it grows.

• Reduced winter hardiness.

• Enhanced nutrient deficiencies.

• Spreading of disease.

So with all these reasons to properly prune palms, how should they be pruned? Ideally, a healthy palm has a canopy that is almost 360 degrees around, or circular in shape. However this is rare in our landscapes as folks feel the need to create a more formal look.

When pruning, the best method would be to only prune out dead fronds. Fruit and flower stalks can also be pruned at any time. You may also be tempted to remove lower fronds that are displaying a nutrient deficiency. Resist this temptation. The palm is moving the scarce nutrients from the older fronds to the newer fronds. Pruning out these “ugly” fronds causes the tree to mine the needed nutrients from the next level of fronds, causing them to look deficient. It is a harmful cycle that usually results in the death of the tree.

In order to reduce the frequency of having to prune, the rule of thumb is to prune no higher than horizontal. Another way to look at it is that the outline of the canopy should be no higher than 9 o’clock and 3 o’clock on a clock face.

To reduce the transmission of serious palm diseases, the pruning tools should be sterilized before pruning each tree. Solutions to disinfect pruning tools include pine oil cleaner, alcohol and denatured ethanol. A bleach solution can be used; however, bleach has been known to be corrosive.

As more and more palms are maintained properly, the under-fertilized, and over-pruned palms will start to become less common in our landscapes. Hopefully then properly maintained palms will become the norm instead of the exception.

Larry Figart is an urban forestry extension agent with the University of Florida/Duval County Extension Service.