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Index : Plant Care
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- 26. Palms Need Special Care - Top
- If your palms are looking a little peaked, it could be their not getting the care they need. Although some varieties of palms, such as the "true" date palm (Phoenix dactylifera), and Mexican fan palm (Washingtonia robusta) come from arid regions of the world, they need some special care to flourish here in the Sonoran desert. The reward is a luxuriant tropical appearance that provides a pleasing compliment to equally exotic native species; like the saguaro and octopus agave.
Deep water on a regular basis. Even palms adapted to arid regions, such as date palms and Mexican fan palms benefit from watering every two to three weeks during the spring and summer. Other palm species originating in moister regions of the world, such as queen palm (Syagrus romanzoffiana) and pindo palm (Butia capitata) need watering every one to two weeks.
Water deeply, so that the soil is wetted to a depth of two feet. Palm roots will extend out as far as irrigation is provided from the trunk. Water out from the trunk a minimum of four feet. A watering basin can be made by forming a circling ridge of soil several inches high.
Fertilize with "palm special" fertilizer. Palms have exacting needs when it comes to nutrients. Scientific research has determined the best ratios of macro and micro nutrients. These are now available in so-called "palm special" fertilizers. Not all such fertilizers are the real thing. Look on the label to make sure the nutrients are in the following proportions: nitrogen (10% to 20%), phosphorous (5% to 10%), potassium (10% to 20%), magnesium (2% to 5%), and (.5%) of manganese and iron. It should also contain sulfur and trace amounts of zinc and copper. Nitrogen and potassium should be in equal percentages and in a slow release form.
Dry, granular fertilizer should be broadcast or banded under the canopy of the palm, or equally distributed around the drip emitters. Never place fertilizer against the trunk. One application in March and another in June or early July should be adequate. For palms under eight feet tall, 2-5 lbs of fertilizer per feeding should be adequate. Newly planted palms can receive even less (2 to 2 lbs depending on the size). Large, mature palms should receive 5 to 8 lbs each application.
If palms are suffering from nutrient deficiencies, then supplemental amounts of the deficient nutrients will be required. Magnesium deficiencies are common on date palms (Phoenix species). Older leaves turn yellow first, progresssing up to younger leaves. Leaflet tips yellow while the bases remain green. Correction of this deficiency requires the addition of magnesium sulfate to the soil.
Queen palms are often deficient in manganese, not to be confused with magnesium. Manganese deficiency on Queen palm causes the new leaves to become yellow or brown and frizzled, which gives this disorder it's common name: "frizzle top". New growth is crinkled and distorted. Correction of this deficiency requires the addition of manganese sulfate to the soil, and as a spray on the new growth. Manganese deficiency is also common on sago palm or king sago (Cycas revoluta). Although palm-like in appearance, sago palm actually belongs to a family of prehistoric plants called Cycads.
Pruning should never be excessive. Hurricane pruning is a common practice along the Atlantic and Gulf Coasts. All but the very top fronds are removed just prior to Hurricane season. Hear in Tucson we have no hurricanes, and yet the practice of hurricane pruning, or "rooster-tailing" is alive and well. This excessive pruning of palms is not recommended. Only yellowing or brown fronds should be removed from palms. Green fronds manufacture the food reserves to provide for new top and root growth. Removing these fronds gradually weakens the palm, slowing it's growth and making it more susceptible to insect and disease problems.
Sometimes commercial pruning practices dictate the removal of some green fronds, but never should this be excessive. Superimposing an imaginary clock face over the leaf canopy, pruning should never remove those leaves between the 10 o'clock and 2 o'clock positions.
If your pruning your own palms, allow the yellowing leaves to turn brown before removing them. Palms draw the nutrients for the old, yellowing leaves and transfer them to the newer growth. This reduces the chances your palms will become nutrient deficient.
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Written by John Begeman, College of Agriculture and Life Sciences, the University of Arizona, 520-626-5161.
Material originally appeared in Arizona Daily Star gardening column, on June 30, 1996
- Updated: June 30, 1996
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