The tendency is to prune palms severely. Standard practice is to remove all but the top tier of leaves. In coastal areas this is called Ahurricane@ pruning. It is typically done just prior to the hurricane season, with the intention of protecting the palms from high winds. 

In reality, palms need no protection from high winds. Their flexible leaves and low wind resistance make them nearly storm-proof. But the practice of hurricane pruning continues, even in locations far away from the sea. It the Desert Southwest the practice is referred to as Arooster-tailing@ due to the plumed appearance of the remaining leaves.

Rooster-tail pruning is harmful in several ways. Instead of protecting the palm from high winds, the practice actually weakens the canopy. The reason for this is that all fronds (leaves) in the head of a palm act together, with each frond layer supporting and adding strength to the one above. They all protect the bud and newly emerging spear leaf. The more leaves removed, the less strength and protection there is.

Like trees, palms manufacture their food through their leaves. But palms are not as efficient as trees at storing their food for needy times. So palms are more dependent on their leaves to provide necessary food for growth. With relatively few leaves, compared to trees, removing even one green frond can significantly reduce the palm=s ability to feed itself. 

An unpruned Mexican fan palm carries no more than 30 fronds at one time. Typically, as many as 20 fronds may be removed in Arooster-tail@ pruning. That means the palm=s ability to manufacture food has been reduced by two-thirds. Try to imagine if you had to survive on two-thirds less calories a day!

Severe pruning also stimulates an unhealthy survival response in palms. Energy is burned, to quickly produce new leaves to replace those lost. Instead of storing food, palms that are severely pruned begin depleting their reserves of energy. If this happens on an annual basis, the palm=s trunk gradually decreases in diameter and becomes weak. It is more likely this weakened trunk will break or shatter in a storm. 

Palms also move nutrients from the older fronds to the new growth. When all of these older fronds are removed, so is the source of much of the nutrients that palms need. As a result, nutrient deficiencies can develop. These nutrient deficiencies can be difficult to correct.

Ideally, only brown or yellowing fronds should be removed when pruning a palm. If green fronds must be removed, prune off as few as possible. Under no circumstances should palms be severely pruned! Severe pruning is characterized by the removal of any fronds between the 10 o=clock and 2 o=clock positions on the palm canopy. This can be visualized by imagining a clock face placed over the palm canopy, with the 12 o=clock and 6 o=clock positions being aligned with the trunk. 

Finally, it is important that the trunks of palms not be injured. Palms should never be climbed using spiked or cleated climbing shoes. These spikes puncture and wound the trunk, allowing the entry of pathogens that can kill the palm. Pruning should be done by knowledgeable professionals using a hydraulic bucket lift Acherry picker@, pole pruners or ladders.

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 May 16, 1999
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