Richard Bogren, Owings, Allen D.
News Release Distributed 06/13/13
By Allen Owings
LSU AgCenter horticulturist
HAMMOND, La. – The use of palms in home landscapes has gained considerable interest in the last few years. Several reasons have brought about this resurgence. For one, many new, exotic palm species and varieties are more readily available; however, our cold temperatures the past couple of winters have damaged some of the species, and people are searching for the most reliable palms for landscape use.
While most of us now realize that fall and winter are the best times to plant the majority of ornamental plants in our landscapes, the best time to plant palms in Louisiana is May through September. The soil is warmest this time of year, and warm soil is one of the most necessary criteria for palm root growth.
Rough handling of palm trees or severe vibrations during transport can break the tender bud, causing death that may not appear until many months down the road. It also is important to transplant a palm as soon as possible after digging. Never allow the roots to become dry. But this should not be a problem with container-grown plants.
Climate is without a doubt the single largest limiting factor in selecting palms. Louisiana is located in U.S. Department of Agriculture hardiness zones 8 and 9, and many palms will do well for us. Keep in mind, though, the large differences in average minimum temperatures between these zones. Some palms that will do fine in zone 9a (New Orleans, Lafayette, Lake Charles) may have damage in zone 8b (Alexandria, Baton Rouge) and will definitely exhibit damage in zone 8a (Shreveport, Ruston, Monroe).
We do have reliable palms for some of these areas.
Palms regularly planted in Louisiana include the needle palm (Rhapidophyllum hystrix), dwarf palmetto (Sabal minor), windmill palm (Trachycarpus fortunei), cabbage palm, (Sabal palmetto), saw palmetto (Serenoa repens), Mediterranean fan palm (Chamaerops humilis) and cocos or jelly palm (Butia australis or Butia capitata).
A popular palm-like plant for Louisiana is the sago palm. These plants are actually not palms, but cycads. The sago palm is a native of Japan and is hardy to 15 degrees. The 2- to 3-foot-long leaves can be even larger on older plants and are divided into many narrow, needlelike segments. The primary problem with sago palms in south Louisiana is a fungal leaf spot disease to which they are especially susceptible during periods of high humidity. Sago palms, however, are highly recommended and should be planted in the late spring and early summer, just as true palms should.
LSU AgCenter horticulturists Severn Doughty and Dan Gill conducted an extensive survey of palms growing in south Louisiana a number of years ago. They found 14 genera comprising 21 species of palms. Of these, less than half have been found to be statistically reliable for planting due to climate limitations. So you can see that species selection is important.
Realize that many home gardeners, nursery growers and landscapers use palm species that may not be reliable for long-term performance because of cold weather. The desirable characteristics and fast growth rates of some overcome the necessity to replace them once every 10-20 years due to winter damage. Washingtonia species of palms are hardy to about 15-22 degrees but will suffer excessive damage after several consecutive days of temperatures in the teens.
For palm success, select for cold hardiness. It is also important to consider vertical and horizontal space limitations. Once established, palms should be maintained under a moderate fertilization program. During late spring and early summer, remove old leaves and inflorescences as they become unsightly.
You can see more about work being done in landscape horticulture by visiting the LSU AgCenter Hammond Research Station website. Also, like us on Facebook. You can find an abundance of landscape information for both home gardeners and industry professionals at both sites.