by Phil Bergman
General information about various spiny palm trees that can be grown successfully outdoors in Southern California. Palm trees with spines are unique and often sought after by enthusiasts.
With so many species of spiny palm trees in existence, it would take pages upon pages to write about all of them. There are actually a lot more spiny palms than you’d think. Therefore, I will concentrate on a few that can be grown outdoors in some areas of Southern California. Some people love them while others would never consider planting spiny palms. Below are a few species to consider because they look so different.
Acanthophoenix crinita is a rather new addition to the list. We first began propagating this palm about ten years ago. It is somewhat difficult to germinate, but once established is a fast grower. We’ve had good success with plants sold. Reports are that it will take into the low 30º F. Some have grown this species in sun, others in strong filtered light. It is really spiny.
Acanthophoenix rubra is a sought after species with silver on the underside of the leaflet. It likewise seems to be cold hardy but may need a little more protection from sun while small. Both species are quite beautiful.
Acrocomia species likewise can be grown here. Germination is the trick with this genus. Germination requires high heat. Plants are quick growing and require full sun after attaining five gallon size. Species I’ve grown will tolerate temperatures into the low 30º F. Although some taxonomists have lumped multiple species together, growers still appreciate differences between the old “species”. It is often touted that Acrocomia totai is the most cold hardy, tolerating freezes. Most Acrocomias retain spines on the trunks for some time and make very large trees. There are dwarf forms. Look for the specimen Acrocomia at the meeting this July.
Aiphanes are being successfully grown by many palm enthusiasts. At our meeting this month, we will see a flowering Aiphanes caryotifolia. This species tolerates temperatures into the low30º F. With ample humidity, they can grow in full sun. If you have hot and dry conditions, give them some protection. A. caryotifolia is probably the easiest species to grow and the most cold hardy. It grows at a relatively fast rate.
Astrocaryum mexicanum is a beautiful spiny pinnate palm. Even the collected fruits are spiny! Germination is easy with fresh seeds and growth rate is moderate. This species is not a large palm. The specimen in the San Diego Zoo has been there at least twenty years and seen cold temperatures in the low 30ºs F. Anticipate a small trunk about three inches in diameter and a crown that is no more than six or eight feet across. Filtered or broken light is preferred. Other species of Astrocaryum have not proven good for Southern California and Astrocaryum standleyanum will eventually die from our cold winters.
Bactris species have been grown in Southern California. However, they suffer during the coldest winters. Bactris militaris is a stunning plant! Temperatures under the mid 30ºs F. will damage the foliage of most Bactris. If you are attempting to grow this species, acclimate it into fairly strong sun while still trying to give it some overhead protection. Bactris have wicked spines on the trunks and leaves. Be careful not to get poked when you are around palms with spines.
Various Calamus species and related genera are being grown well in Southern California. The attractive Calamus caryotoides makes a nice clumping palm and can be grown in most non-freezing areas. It prefers filtered light. Some have grown it in full sun with success. Other species should be tried, especially non-equatorial varieties. There seems to be promise with some of the northern Indochina species. Most Calamus are easy to germinate and grow at a moderate speed
Plectocomia himilayana is a more recent spiney palm that’s become available on the market. It has spines on its trunk and petioles. Note on the photo to the right how the spines are clustered in groups. It is fairly cold hardy and grows in Southern California.
Some palm species have modified “spines” which are large in diameter and are often attached to the trunks. These are called “needle” palms and are not usually thought of as spiny palm trees. All of the Trithrinax species and Rhapidophyllum hystrix are very easy to grow and have needles on their trunks. Some have interesting trunk fiber as well. Both these genera are fan palms and all are extremely cold hardy. Trithrinax prefer full sun whereas Rhapidophyllum is more beautiful in partial sun or strong filtered light. Growth rates are slow to medium. One of the most interesting “needle” trunk palms is Zombia antillarum. It is a gorgeous suckering palm with the most interesting pattern of swirling needles and fiber on its trunks. Although not as cold hardy as Trithrinax and Rhapidophyllum, Zombia can be grown in warmer coastal areas. It prefers full or near-full sun.
There are some gorgeous spiny palms that will not grow here. These include Verschaffeltia splendida, Phoenicophorium borsigianum, and Salacca magnifica. All three are stunningly beautiful, the first two with prominent orange color. All three of these species will succumb during a freeze and should only be attempted in the most protected areas outdoors in Southern California. And, even then, use a prayer on planting. However, there are many beautiful spiny palms that can be grown here. Palms with spines are truly different. Give one a try!