Fertilization of Palms
by Tom Broome
Past President, Central Florida Palm & Cycad Society
When determining which fertilizer to use on any plant, it helps to understand the growth pattern of the plant in question. Different fertilizers have different release patterns, as well as different lengths of time for the product to work. Also, certain plants are prone to particular minor element deficiencies. Instead of just suggesting any particular fertilizer for your plants, I would rather explain these factors, and let you choose for yourself what fertilizer to use. In many cases the fertilizer I use may not be available to everyone.
Palms have a continuous growth pattern. Once they start growing in the spring, one leaf is produced after another. Some palms tend to get magnesium and manganese deficiencies. When looking for a fertilizer, it is good to get one with as many minor elements as possible. For palms, look for one with at least these two plus iron.
Cycads have an eposodic growth pattern. Leaves are pushed out, extend out, and harden up. Then, after a certain amount of time, another flush will be pushed out. When cycads are young, they produce only one leaf at a time. As they get older, the number of leaves produced each time increases. The more leaves at a time, the more energy required to produce the flush. When young, a cycad may produce leaves every two to three months. When older, many cycads in the garden will only produce leaves once a year, or even once every other year for some species. On my young cycads, I use a time release fertilizer. As they get older, I use a fertilizer that has a faster release pattern to increase the number of flushes per year. For cycads as well, it is good to buy a fertilizer with as many minor elements as possible. Manganese is probably the most important, especially with the king sago, Cycas revoluta.
But what fertilizer should you buy? Instead of asking me, or the person selling fertilizer in the store, you need to know how to read the label on the bag or box. In many cases there is nothing on the label that tells you how long the product lasts or how fast the product releases in the soil. Of the three large numbers that everybody is used to seeing, the first represents nitrogen. The key to it all is on the back of the container in an area called " nitrogen derived from". Urea is a fast releasing nitrogen that probably will not last more than a month. Ammonium nitrate, or something close to that, will last one to maybe two months. Insoluble nitrogen does not dissolve in water rapidly, so this is a type of longer lasting nitrogen. Time release nitrogen can be sulfur coated, polymer coated, and other type products. Most of these types should have the duration of release on the label. It is good to keep in mind that a sulfur coated fertilizer can increase the acidity in your soil. The second of the three numbers is phosphate. The only time this is really important is when you may want to produce flowers and seeds on palms. By reducing the amount of nitrogen and increasing the amount of phosphate, you will produce more flowers on your palms. The third number is potassium. This helps with the general health of your plants. Most fertilizers you buy should have enough of this chemical, so this is not really all that important.
When growing palms you need to keep the energy as constant as possible. This constant release will maximize the continuous growth pattern. If you use a time release fertilizer, it can be applied once or twice a year, according to label instructions. Nutricote or Osmocote are examples of such products. What if you can't find one of these products? There are many "palm special" fertilizers on the market. Look at the label, and use the product as often as is needed. If you are using a fertilizer with urea as it's only nitrogen source, you may have to apply it every month. A product with ammonium nitrate as it's only source has to be used maybe every other month.
When growing young cycads, use a time release fertilizer. I also use a time a release fertilizer on Zamias and Macrozamias. Zamias have a tendency to split when grown too fast, and Macrozamias seem to have more of a continuous growth pattern when they get larger. As your cycads get larger, it will be more important to use a faster release, high nitrogen fertilizer. When the plants get to the stage that they are producing more than three leaves at a time, they seem to slow down. This is a good time to switch to the faster release fertilizer. I have found that using this type every three to four months will increase the number of flushes per year. If you want to produce cones on cycads, use a fast release, high nitrogen fertilizer two months before the expected emergence of cones. Each species has it's own timing, and you will have to study the coning pattern of each species in your area to determine when this might be. Keep in mind that any time you use a fast reacting, high nitrogen fertilizer, that you use it according to label instructions. Using too much can burn and sometimes kill your plants.
I hope this article has helped everyone to grow your palms and cycads more efficiently. Instead of taking the word of someone else as to the product that you should use, you can make your own determination of what is the best product in the right situation.
President, Central Florida Palm & Cycad Society
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