Trees - Palms

by Jim Hoare, Master Gardener

Introduction

So, what is a palm? They are certainly not a tree – although we like to call them Palm Trees. Palms belong to the division of flowering plants called monocotyledons or monocots that include lilies, grasses, irises, orchids and others.

Most palms are reasonably drought tolerant. They usually can not tolerate having “wet feet” – but established plants can take short periods of excessive water (which we seem to get in our area fairly often). You can plant a certain number of palms quite successfully in the Houston/Galveston area. Please refer to the table included in this article for a listing of some of the more common types of palms that can be grown here.

Planting

Palms should be planted any time between spring and mid-summer so as to ensure they are properly established before winter. They prefer a well drained, fertile and slightly acidic location – although they also appear to be growing quite well in our alkaline, clay soils. When digging a hole to plant a palm a good rule of thumb is to make the hole twice the width of the root ball. The depth of the hole needs to be just enough to accommodate the root ball. It is best that you do not amend the soil. If really necessary, don’t add any more than 25% new soil and keep at least 75% of the existing soil. You should keep a ring of mulched bed or border around the palm so as to keep the lawn away from the trunk. The trunk of a palm can be easily damaged by lawn cutting or by driving a nail into the trunk for a support. Any damage made to the trunk is permanent. Unlike trees that repair themselves when their bark is damaged, palms do not repair themselves. This in turn makes the tree more prone to access by insects or pathogens.

Fertilizing and Watering

Palms should be watered so as to keep the soil moist – but not wet. Some palms are fairly drought tolerant (see table) and can be reasonably forgiving about the amount of water they receive. Turf fertilizers are generally not compatible with palm nutrient requirements. Turf fertilizers usually have too much nitrogen and can accentuate deficiencies of elements such as potassium. It is recommended that a slow-release fertilizer formulated for palms be used that has a 2:1:3:1 (N:P:K:Mg) ratio. Apply at a rate of 1 ½ lbs/100 sq.ft. of canopy area every 2-3 months if the soil is sandy. Use 1 lb/100 sq.ft. for clay soils. I have also been advised that composted manure contains all of the necessary elements to keep any plant healthy - including palm trees.

Pruning

Palms need to be pruned on a yearly basis. The best times to prune are spring and early summer. Only remove dead, badly damaged, or diseased leaves. Do not over-trim by taking off healthy leaves as this reduces the food manufacturing efficiency of the plant. When pruning, make the cuts as close to the trunk as possible and try to make the cuts at the same angle. This will help you to obtain a clean, neat pattern on the trunk.

Common Problems

Palms are usually pest-free but they can be affected by scale, red spider mites, mealybugs and chewing insects. Most insect damage occurs to very young plants and can be treated with an application of dormant oil during cooler weather (between 40ºF and 70ºF). General purpose sprays can be used in the warmer months. The other problem you can encounter is mineral deficiencies. These include the following:

Potassium (K) deficiency - always appears first on the oldest leaves. Early symptoms are small 1 –3 mm translucent yellow or orange spots on leaflets.
Magnesium (Mg) deficiency - the tips of the leaves turn yellow while the inside or base of leaves stays green
Iron (Fe) Deficiency - appears on newest leaves as interveinal or uniform chlorosis
Manganese (Mn) deficiency - new growth come out as small, chlorotic leaves with longitudinal necrotic streaking. As the deficiency progresses, succeeding leaves emerge frizzled or withered. It’s usually caused by a high soil ph.

COMMON NAME	SCIENTIFIC NAME	LEAF TYPE	MIN. TEMP	COMMENTS
Queen Palm	Syagrus romanzoffianum	Pinnate	24º F	Grows up to 40 ft. tall with a single trunk. Fast growing palm that likes full sun or part shade
Pindo or Brazilian Jelly Palm	Butia capitata	Pinnate	15º F	Grows up to 20 ft. tall with a single trunk. One of the hardiest of palms for this area. Likes full sun or part shade.
European Fan Palm	Chamaerops humilus	Palmate	18º F	Grows up to 40 ft. tall and is usually multi-trunked. Grows well in full sun or part shade.
Mexican Blue Palm	Erythea amata	Palmate	18º F	Grows up to 40 ft. tall with a single trunk and leaf widths of about 6 ft. It is a very hardy palm that is tolerant of dry conditions. Needs to be grown in full sun.
Chinese Fan Palm	Livistona chinensis	Palmate	22º F	Grows up to 25 ft. tall with a single trunk. Likes moist, organic soil and light to moderate shade – but will grow in full sun.
Australian Fan Palm	Livistona australis	Palmate	20º F	Grows up to 50 ft. tall with a single trunk. Likes full sun, well-drained soil and is fairly drought tolerant.
Canary Island Date Palm	Phoenix canariensis	Pinnate	20º F	Grows 80 – 100 ft. high with a single trunk that can be 1 – 2 ft. in diameter and leaves 10 – 20 ft. long. This palm likes full sun.
Date Palms	Phoenix dactylifera	Pinnate	20º F	Grows up to 60 ft. tall. This is a fast growing palm that does well in Houston. Prefers moist soil in full sun. May be single or multiple trunk.
Texas Palmetto	Sabal mexicana	Palmate	18º F	Grows up to 40 ft. tall with a single trunk that can be 1 to 3 ft. in diameter. It likes moist conditions and grows well in sun or part shade.
Florida Cabbage Palm	Sabal palmetto	Palmate	10º F	Grows up to 100 ft. tall with a single trunk that can be 1 to 2 ft. in diameter. Likes moist conditions and grows well in sun or part shade.
Dwarf Palmetto	Sabal minor	Palmate	5º F	Grows up to 10 ft. tall. Likes moist conditions and can withstand growing in dense shade. It is usually trunkless.
Texas Sabal Palm	Sabal texana	Palmate	12º F	Grows up to 60 ft. tall with a single trunk that can be up to 3 ft. in diameter. Likes moist conditions and grows well in sun or part shade.
Hispaniolan Palmetto or Royal Palm	Sabal umbraculifera	Palmate	10º F	Grows up to 60 ft. tall with a single trunk that can be up to 3 ft. in diameter. It likes moist conditions, sandy soil, and grows well in sun or part shade. This palm has huge leaves (up to 10 ft. across)
Windmill Palm	Trachycarpus fortunei	Palmate	10º F	Grows up to 40 ft. tall. A very hardy palm that likes moist conditions and will grow in full sun or part shade (they seem to do better if given a little shade).
Himalayan Palm	Trachycarpus takil	Palmate	10º F	Grows up to 10 ft. tall with a single trunk. Likes full sun or part shade and moist, well-drained soil.
Mexican Fan Palm	Washingtonia robusta	Palmate	22º F	Grows 80 to 100 ft. tall with a single trunk that can be 1 to 2 ft. in diameter. A drought resistant palm that grows rapidly and likes full sun.
Needle Palm	Rhapidophyllum hystrix	Palmate	5º F	Grows up to 10 ft. tall with multiple trunks. Likes moist conditions and grows best in light shade.
Afghanistan Palm	Nannorrhops richtiena	Palmate	16º F	Grows up to 15 ft. tall with multiple trunks. Likes full sun and is fairly drought tolerant.
Chilean Wine Palm	Jubaea chilensis	Pinnate	12º F	Grows up to 80 ft. tall with a single trunk and diameter of 4 –6 ft. Likes moist conditions and grows best in full sun. This is a very slow growing plant.
Everglades Palm	Acoelorrhaphe wrightii	Palmate	23º F	Grows 20 to 40 ft. tall with multiple trunks. Likes full sun and can take high heat and dry conditions – but will also tolerate damp soil once plant is established
Dwarf Sugar or Formosa Palm	Arenga engleri	Pinnate	23º F	Grows up to 10 ft. tall with multiple trunks. Likes full sun or part shade. Prefers warmth and deep room for the roots.
Gru-gru Palm	Acromcomia totai	Pinnate	23º F	Grows up to 25 ft. tall with a single trunk. Likes partial shade or partial sun in moist, well-drained soil. Trunk is spiny – but spines can be removed.
Mexican Cliff Palm	Brahea dulcis	Palmate	25º F	Grows up to 25 ft. tall with a single trunk. Likes full sun and well drained soil.
Saw Palmetto	Serenoa repens	Palmate	18º F	Grows up to 20 ft. tall with multiple trunks. Will thrive in a great variety of conditions from swamp to drought but prefers well-drained conditions with full sun or partial shade.
Sago Palm	Cycas revoluta	Pinnate	15º F	This is not a palm tree but included here because of their popularity in this area. They can grow in full sun but also do well in part-sun. They grow slow to a typical height of 6 to 10 ft.

Notes:

Pinnate is feather-type leaves. Palmate is leaves that resemble the palm of your hand.
The minimum temperatures are a general guide. Material available on this is quite wide ranging and so I’ve tried to use a conservative number for the purposes of this article.
The above list is a selection of palms that can be grown in this area. It is not an all-inclusive list and there are other palms that can be grown here – provided you can find them in the local nurseries.