Winterproofing palms to survive climate change

You have probably already seen one: a tall palm tree wrapped in strips of burlap which the owners hope will protect the tree during winter cold. In truth, this burlap bandage going from the ground to where the fronds begin is unlikely to have any impact at all.

There is, however, a proven way to “weatherproof” and protect palm trees in areas where winter temperatures sometimes fall below freezing–places like Palm Springs, Tucson, Las Vegas and London. That’s right–palm trees are now being planted and thriving in London in the U.K., a city that is further north than Seattle.

Climate change is definitely having an impact on gardens worldwide and on which plants will thrive where. While we think of palms as warm climate trees, they are now being planted in areas where cold, freezing winters are normal. And future changes in weather conditions are becoming more unpredictable, except that it looks like extremes of hot and cold will become normal.

The Proven Way to Protect Palms

So here is how to look at the situation: The best way–the proven way–to winterproof palm trees, which thrive in warm to hot weather, is to start off right and plant one of the palms that are also hardy–one that has built-in DNA resistance to winter chill. And you may be surprised at how many palm trees fit this requirement.

Let’s start with my London friend’s palm tree which she was told by her local garden center was a “New Zealand palm”. I recognized immediately that New Zealand had nothing to do with it. Her palm was and is a sturdy, hardy multi-trunk Mediterranean Fan Palm (Chamerops humilis).

Ideal for small gardens, this short shrub-like palm has survived brief cold spells down to zero F. (-18 C.) And “brief” is the important factor; their survival depends on daytime warming after a night of chill. It has been 14 years since she planted it in a sheltered corner and, growing slowly, it still survives, and recently has even bloomed and produced fruit.

The next on this list of chilly-weather survivors is the Date Palm (Phoenix dactylifera), a native of the Middle East. It’s the tree you probably think of when someone says “palm tree”. Tall with long pinnate (rather than fan-like) fronds, this 75 foot high giant is very hardy. It has been known to survive and regrow after experiencing temperatures down to 5 F. (-16C.) Dates are, obviously, edible and the difficult-to-find Bahri dates are the very best. Unlike the chewy Medjool dates you buy in a store, Bahri dates are soft, delicious and taste like caramel.

Next is the Date Palm’s cousin, the Canary Island Palm, (Phoenix canariensis). While a few of these palms have reached a mature height of over 130 feet, that is uncommon. But they still are among the tallest palms. It will withstand temperatures to 20 F. (-7 C.) at least for a short time.  After a cold snap the fronds will turn brown and may very slowly regrow.

Tall palm trees native to the West

More common in gardens here in the West are two fan palm trees. The California and Mexican Fan Palms, (Washingtonia filifera and W. robusta), natives of Southwestern U.S. and northern Mexico, are also rugged, surviving cold weather as low as 18 F. (-8 C.)

Trimming the “hula skirt” of dead fronds off these trees may make them look a bit more tidy but that “skirt” offers the palms some protection, some insulation from severe weather. The downside of not removing dead fronds is that Mother Nature may do it for you during our fierce Spring and Fall windstorms. And falling palm fronds are very dangerous. The thorns on these fan fronds are also hazardous.

Like the date palms, the Washingtonias can reach heights of 60 to 100 feet, making them not particularly suitable for residential gardens although we see them planted around homes everywhere. After a few years’ growth they are more like architectural columns in a yard than trees.

Shorter palms for home gardens

A native of Mexico’s rocky Guadalupe Island, the Guadalupe Fan Palm (Brajea edulis) is a distinctive palm with a smooth grayish-brown trunk and silvery fronds. It grows about a foot a year to a mature height of only 25 feet tall, ideal for a residential garden. It flowers in summer from long drooping stems and the blooms are fragrant. Because it is a native to a small island with variable weather conditions, it tolerates heat, wind and drought, and it is one of the hardier palms, to 18 degrees F. (-7.7 C)

Pindo Palm (Butia capitata) , a native of dry South American savannahs, is another short palm, growing only to 20 feet. In Florida where it is popular in home gardens, it is known as the Jelly palm because people make jelly with its fruit. It tolerates temps as low as 5°F (-15 C) In this photo a very young Pindo palm was planted at the same time as the Washingtonia behind it. They have very different growth rates.

Originally found in high altitudes in China, Japan, Myanmar and India, the Windmill Palm (Trachycarpus fortunei) is a semi-dwarf palm with windmill-shaped fronds. Slow-growing to 15 feet tall, this tree loves our summer heat but will withstand winter temperatures of -10F (-23C).

My favorite fails the chill test

My favorite is the graceful Queen Palm (Syagrus romanzoffiana) a native of South America commonly planted in Southern California. It does not do well at all in cold weather. While I’ve seen it planted in hot dry Palm Springs, but with the weather uncertainty stemming from climate change, it may not survive there at all, except in a local micro-climate. Nearer the California coast, it grows beautifully and is ideal for home gardens.

And finally…

If a freeze comes and your palm tree ends up with browned fronds, do NOT remove it right away. Give it a few weeks or even a month or two of Springtime weather and it may very well produce green fronds again. And if you have to replace it in the end, choose one of the palms on this list.

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