Home & Garden

March 7, 2013

Local gardening: The right way to prune palmettos

Amanda McNulty: Our state tree, Sabal palmetto, all too often gets over-zealously and incorrectly pruned.

Garden writers recently have reminded us that now is the time to prune. Last weekend, I rode through Edgefield County and thousands upon thousands of peach trees sported trimmed, upright limbs waiting for blossoms to appear. Overgrown foundation plants, branches hanging in walkways, nandinas up over the window frame — all are being addressed by gardeners armed with pruners, loppers and saws.

We in the Palmetto State often consider ourselves uniquely knowledgeable on many issues. Sadly, our state tree, Sabal palmetto, of which we are so proud and plant in every possible nook and cranny, all too often gets overzealously and incorrectly pruned.

The natural aging process for palmetto fronds is for the entire leaf to slowly turn brown, over several years. During that time, the edges get ragged from wind damage and the leaves may hang down if an ice event has occurred. Many a tidy landscaper or homeowner wants to only have perfect leaves swaying in the summer breezes. However, your tree has a balance between the photosynthates, foods, which the leaves can generate and the roots that provide water and dissolved nutrients. Cutting off older leaves that are a little tattered or brown starves some of the roots below, causing them to die and become entry points for disease.

Clemson’s Home & Garden Information Center has a fact sheet on palms and cycads (HGIC 1019). In the section on pruning palms, they caution to never remove a leaf unless the petiole (the structure that attaches the leaf to the trunk) has turned brown. And as attractive as you may find an up-do, never prune off leaves that are growing at an angle less than 90 degrees; i.e., leave all the fronds that are oriented horizontally to the ground and above.

Palmettos are monocots and therefore more closely akin to turfgrass than to a pecan tree. We fertilize pecan trees in March as they are beginning their active growth then. Palmettos, however, are warm weather fellows, and, just like warm-season turfgrass, should not be fertilized until the ground is warm and the plants are actively growing, usually in April. Most palm family members are very susceptible to nutrient deficiencies from low potassium and magnesium. If your palmettos are growing in turfgrass, you actually need to use the fertilizer recommended for the trees rather than the grass. Fortunately, the ratio is similar to that for most turfgrasses with the inclusion of the additional nutrient of magnesium.

Surprise, surprise!! Our famous $6 Clemson Extension soil test system now allows you to get a recommendation just for your palm trees. If cosmetic surgeons gave dollar value like we do at our soil test lab, I would be wrinkle-free and have a nose like Ingrid Bergman’s.

Although our state tree has migrated towards the Upstate in recent years, a really cold winter may kill many that aren’t protected. Happily, one of our most beautiful native palms is the hardiest in existence. Although needle palm, Rhapidophyllum hystrix, is smaller, it eventually achieves a size of eight or 10 feet in height and width. It grows so densely it completely fills its space and is shade tolerant. As more and more of our natural flood plains are drained or altered, this palm is losing its natural habitat. Once difficult to find, you can now obtain it in containers easy to transplant and at a reasonable price. Maybe not S. palmetto size, but it’s bigger than the decal you put on your car’s rear windshield!

Amanda McNulty is an associate extension agent for the Clemson University Cooperative Extension Service and the host of “Making It Grow!” broadcast weekly on ETV television stations. Website: www.clemson.edu/extension/hgic/ Check out her blog at the Making it Grow! page at www.scetv.org

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