Mexican and California Palms are Not That Easy to Tell Apart. Or Are They?

Q. My husband and I are snowbirds from Canada. We try to have our yards as low maintenance as possible. The Mexican fan palms in our backyard are bulging up, pushed and broke the bricks on the ground again. How often are these pruned? Will they get much bigger?

Mexican fan palm, Washingtonia robusta, is known for its height and the narrow trunk. California fan palm, Washingtonia filifera or desert palm (palm on the bottom), is known for its broad trunk and shorter stature.

A. Two most common palms considered for home landscapes are the Mexican and California fan palms. The difference between the two is that Mexican fan palm has a narrow trunk while the California fan palm has a very wide trunk. These palms interbreed with each other so it's very difficult to know exactly what you have even though you bought supposedly a narrow trunked "Mexican fan palm".

So, unfortunately, it's hard to predict how wide across your fan palm will get even though it's called "Mexican fan palm". When these fan palms grow about 10 feet tall, the width of the trunk probably won't change a whole lot. Palms grow differently than trees and they don't get much wider with age due to a lack of secondary growth after a few years.

Even the so-called experts have trouble telling them apart!

Is this W. filifera?

Which is which? Or are they both the same?

Mexican and California fan palms gets 60 (California fan palm) to 100 feet tall (Mexican fan palm). There are other palms that stay smaller than this and are better suited to residential landscapes. These palms produce seed from the flowers in about April. If you have your palm pruned at that time of year you can have the flower stalks removed as well as the palm fronds. This eliminates seeds from being spit and germinating everywhere or landing in your pool.

Palm seedlings like this one start easily when water is present.

It's best to prune these palms every year but you could get by with pruning the fronds off every two years. Ideally you want the palms pruned so that the head of it is a half-circle. This means only removing fronds below horizontal. I would discourage you from having it pruned as a "feather duster" with only a wisp of palm fronds at the very tip. Landscape maintenance companies encourage homeowners to do that so that you can get an extra year before pruning again. I wouldn't recommend this as it weakens the palm.

Mostly Mexican fan palms pruned improperly like a feather duster.

            Personally, I think these palms are too large for residential landscapes and it's best to have them removed when they're young. It's expensive to remove them when they're older.

            By the way, they won't produce shade of any amount as they get taller, and they are water guzzlers compared to the shade they produce.