Most gardeners have never given any thought to growing a palm outdoors in Oklahoma, assuming that they are all tropical plants which can't survive our winters.  In reality, there are a few palms which can thrive here, despite our winter cold and summer heat.  We actually have a native population of one species, the Dwarf Palmetto Sabal minor in southeast Oklahoma.

The absolute hardiest palm is the Needle Palm Rhapidophyllum hystrix, native to the southeastern U.S.  It has been known to survive 20 degrees below zero.  Needle Palms grow new plants from the base called "pups" which can be removed to propagate.  Most Needles will reach 3-6 feet in a few years, but some have been known to reach more than ten feet, and a clump with pups can be many feet in diameter.

 Next in line is The Dwarf Palmetto, Sabal minor, which has survived similar temperatures, and usually doesn't even get leaf damage at near zero temperatures.  Sabal minor usually only reaches 2-4 feet in height, with fronds (leaves) two to three feet across.

The Louisiana Palmetto is considered by botanists to be the same plant as Sabal minor, just growing in better conditions and getting larger.  Actually, it is genetically different, growing much larger and faster than Sabal minor, even under the exact same conditions.   We use its original name, Sabal louisiana. Sabal louisiana is slightly less hardy than the two preceding species (some plants will begin to damage between zero and ten degrees), but its much larger size and speedier growth make it a good choice for many gardens.  In the wild, some louisianas grow more than 20 feet, in cultivation they can reach 4-10 feet in 5-10 years, with fronds more than six feet across.

A few other palms are being grown experimentally in Oklahoma, but they all tend to damage in average winters, and may be killed outright if not given some active protection in a worse than average winter.  These include Windmill Palms Trachycarpus fortunei, Mediterranean Fan Palms Chamaerops humilis, California Fan Palms Washingtonia filifera, and Saw Palmetto Serenoa repens.

To Trunk or Not to Trunk

The three most reliable palms for Oklahoma (Needle, minor, and louisiana) can't really be expected to grow trunks of any size in a reasonable amount of time.  Sabal minor almost never grows an above ground trunk (preferring instead to grow a small trunk underground).  Needle Palms can grow a trunk of a few feet, but only after many years. Sabal louisiana grows a trunk in much of its native range, but even in cultivation it may take 10-20 years for it to begin trunking.

There is one very promising palm on the horizon.  Sabal 'birmingham' is an extremely hardy palm which has survived -11 degrees in Tulsa.  It grows quite large, producing a small trunk  in about ten years. It is not known for sure what species it is (many believe it to be a hybrid).  We now have a limited number of 1 and 5-gallon plants available for local retail sales.

Planting and Care of Sabal Palms

Sabal minor can be planted successfully almost anywhere in the Oklahoma City landscape, from protected microclimates to exposed open areas, and from full sun to heavy shade.

Sabal louisiana does best against a hot, sunny south wall.  This will provide shelter from cold, damaging north winds and allow for maximum growth.  Sabal louisiana can be grown in more open locations, but growth will not be as robust, and dry, cold winds may cause more winter damage.  Heavily shaded locations (such as north facing walls) should be avoided altogether.

Both Sabal species love water and do best in moist (but well drained) soil.  Do not plant either in poorly drained, constantly muddy or anaerobic soil, such as the shoreline of a pond or lake.  Sabals naturally grow in swamps and flood plains, but always on higher ground that is above the water line  most of the time.

Dig a hole 1/3 larger and three inches deeper than the growing container.  Gently remove the root ball from the container and place in the center of the hole.  Back fill with the soil removed from the hole.  It may help to "mud in" the hole by adding water to the back fill, to avoid leaving air pockets below ground level.  Do not amend the soil with organic material, as it will decompose and create unstable soil levels, exposing the roots and trunk.

If you received your Sabal by mail order, a little more preparation is needed. Unpack the plants as soon as they arrive, and soak them in a bucket of room temperature water overnight.  Ideally, you should repot the bare-rooted plant you get in a well-drained potting mix and keep it in a bright, humid location (but out of direct sunlight) until you see new growth starting.  If you must plant it outside right away, choose a location where you can provide shade for the first few weeks.  A newly planted bare-root specimen is much more susceptible to sun, wind and cold damage than an established plant.  Be sure to "mud-in" new bare-root plants, to avoid air pockets below ground level, and keep the soil moist for the first few weeks. Finally (I know this hurts) it is a good idea to trim off some of the outer leaves.  The process of transpiration (water loss through the leaves)  often occurs faster than a newly installed, bare-rooted plant can absorb water through the roots, especially in dry, windy or sunny locations.  Trimming some of the outer leaves makes it less likely that the plant will self sacrifice leaves if transpiration losses are too high. I personally hate cutting off leaves, but it is a good idea if planted anywhere with low humidity.

Water new plantings regularly the first season.  Sabals are very drought tolerant after they are well established, but will grow much faster and larger if irrigated regularly.

Newly planted palms will benefit from light applications of a good fertilizer, but can easily damage from too much.  Mix commercial fertilizer slightly weaker than the manufacturer suggests.  Established Sabal palms have deep fibrous root systems which can easily scavenge for nutrients, so supplemental fertilization is not necessary.

Don't over groom the palm's crown.  Every frond that is still at least partially green is feeding the plant, and speeding its growth.  The plant may not look quite as nice with old, partially dead leaves on it, but the longer you wait before removing them, the better the plant will grow.