I once had a neighbor who was a bit lackadaisical about winterizing his palm trees. I asked him once why he made no preparations at all for them and he said that with the planet warming, he didn’t think it was appropriate.
And while it’s true that the temperatures in my area have warmed overall, that doesn’t mean we don’t still have cold periods. One year, we had an unusually cold winter and his poor plants didn’t make it.
If he had taken some steps to protect his palms, they might have survived. As it was, he had to hire a company to dig them up and his yard looked naked for years to come.
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Whether you are growing cold-hardy palms or tropical types, whenever the temperature drops below their tolerance, you’ll need to provide some protection.
Winterizing doesn’t have to take much effort, and it can make all the difference in the health of your plants. So, to help you with the process, we’re going to discuss the following in this guide:
True palms – plants in the Arecaceae family – vary widely in what kind of temperatures they can tolerate.
For example, needle palms (Rhapidophyllum hystrix) are hardy to -20°F, or Zone 5. Some Raphia species can’t handle anything lower than Zone 10.
You don’t need to worry about protecting your palm until the temperature is near the low that it can tolerate.
It’s actually healthy for them to be exposed to some cold, so you don’t want to start preparing for winter too soon.
We want them to experience some cold because it signals to the plant to slow growth and go dormant or partially dormant during the winter.
Also, be sure to feed your palms as recommended for the species during the growing season. A plant that lacks nutrients is less able to survive cold weather than those that are healthy and robust.
But it’s important not to fertilize right before the cold weather because you don’t want to encourage them to put out more growth when they should be going to sleep.
By the way, palms aren’t true trees, but we’ll continue to refer to them as such.
They might look and act like trees, but the vascular system isn’t like a traditional tree at all, it resembles that of ornamental grass. They don’t have bark or a cambium layer.
Palms are technically monocots – plants with seeds that contain one embryonic leaf, while trees are dicots – plants with seeds that contain two embryonic leaves.
You can learn more about palms and how to grow them in our guide.
So, with that out of the way, let’s get into how to winterize these plants. First, we’ll talk about how to care for potted plants.
Potted Plants
Are you growing your palms in pots? Great! You don’t have to do nearly as much to prepare potted plants for winter as you do with in-ground specimens.
Wheel or (yikes!) carry the pot inside and put it in a warm spot that receives as much or slightly less sun exposure as the tree was receiving outside.
You should do this gradually over the course of a week to reduce the chances that the plant will drop its fronds.
Think of it a bit like reverse hardening off – take the plant indoors for an hour or two and then move it back outside. The next day, double the indoor time. Continue for up to a week.
When you have the plant in place, over the winter months give it about half the water it was receiving outside.
Depending on the species, that might mean letting it dry out completely for a few days before you water again.
Don’t fertilize while the plant is indoors.
When temperatures are consistently above the lowest that your particular species can handle, you can move the plant back outdoors. And don’t forget to do this gradually!
As an alternative, if you want to force a potted plant into dormancy, you can move it into an unheated garage or basement once the weather turns cold.
You want a spot that won’t drop below freezing but will remain between 40 and 60°F. You want a good amount of bright, indirect light, but it shouldn’t be in direct light.
The goal is to stop growth while keeping the palm warm enough to survive the winter.
Allow the soil to dry out completely between watering.
When the temperatures climb back up into the right range, harden the palm off for a week or two and move it back outside.
Either method works perfectly well for hardy palms, though most tender types do better inside the home or in a greenhouse rather than an unheated garage, simply because they don’t have the same dormancy period of hardier species.
Winterize in Place
When you fall in love with a plant that isn’t quite hardy to your growing Zone, some gardeners opt to do what is known as “Zone pushing.”
This refers to growing a plant that isn’t suitable for your Zone and providing protection during the winter months.
Palms are a popular choice for zone pushing. You may be growing a species that’s hardy to just one Zone above your region or perhaps more.
For all plants, add a thick three- to six-inch layer of mulch to protect the roots. Straw, leaf litter, or shredded bark are good options.
Whole leaves from deciduous trees make excellent mulch because they release heat as they break down.
When the roots are protected and kept warm, the palm can continue to absorb moisture and nutrients as needed and can regenerate should some part of the crown be damaged.
In addition to protecting the roots with mulch, you’ll need to cover the plant. After you have applied your mulch, tie up the fronds loosely with twine or thin rope.
If you don’t want to tie up the leaves, either because they’re prone to breakage or they aren’t long enough, you’ll need to construct a frame around the plant to drape the cover over. This can be as simple as stiff wire or a custom wood frame.
Take some frost cloth or burlap and starting at the base, wrap the plant or frame from bottom to top. No part of the plant should be exposed. If it is, that area of the specimen may experience cold damage. Secure the cloth in place using twine or rope.
That should be enough if your plant is just one Zone outside of its recommended hardiness Zone. Each layer of burlap or cloth that you use can provide about 2°F of warmth.
If you are growing your palm two or more Zones away from its hardiness rating, wrap chicken wire around the burlap and train incandescent Christmas lights up the wire.
You want the strands of lights separated by four to six inches of space. If you’re using an extension cord, make sure it’s rated for outdoor use, and avoid using LED lights as these don’t put off any heat.
It’s important not to allow the lights to come into contact with the tree as the heat can damage the fronds.
When the lights are in place, tent or wrap foil insulation or bubble wrap around the plant and cover it with a tarp.
You don’t need to leave the lights on all the time. They can be turned off during the day or whenever the temperature is above 15 degrees below the tolerance range for your particular species.
Whenever temperatures drop below that 15-degree mark, go ahead and turn on the lights.
If the weather warms up a bit during the winter, remove the outer layers surrounding the lights.
The insulation and tarp can trap moisture inside the tent, which can promote rot or fungal issues.
When the weather starts to warm up, gradually remove the protection. First, remove the tarp and insulation and leave it like that for a few days. Then, remove the burlap.
Finally, remove the mulch gradually over the course of a week.
Cold Damage
In spite of your best efforts, it’s still possible that your palm ends up suffering from some cold damage.
The result is leaf discoloration, with the foliage turning black, brown, or yellow. There might also be spots of necrosis. Red blotches, bleached leaf tips, wilting, and dropping fronds might also occur.
The trunks can also show symptoms of cold damage, including sunken reddish areas, cracking, necrotic spots, and decay where fungi and bacteria invade the damaged tissue.
When the trunk is damaged, in most cases the tree will eventually die – like those of my neighbor.
Don’t remove any of the damaged fronds until the threat of cold weather has passed. Once it’s safe, pull out each dead leaf.
They should come out readily. Trim off any damaged areas but leaves that haven’t died entirely can remain in place.
If the trunk is damaged, treat it with copper fungicide whether or not you see any signs of disease.
Copper is both a preventative and a treatment for fungal diseases. Be sure to follow the manufacturer’s directions closely and reapply every two weeks for two months.
I always keep copper fungicide in my gardening toolkit because it’s useful for addressing a number of diseases on most common garden species.
You can find Bonide Copper Fungicide available at Arbico Organics in 16- or 32-ounce hose ends, 32-ounce ready-to-use spray, or 16-ounce concentrate.
If you’ve experienced fungal issues in the past, it never hurts to spray your plant preventatively before overwintering.
Don’t Let Winter Get You Down
Palms conjure up warm days, sitting in a hammock with a good book, and listening to the ocean waves.
We don’t generally think of frost and snow when we picture palm trees. But depending on where you live, winter can be a reality we have to face. And that means protecting your plants.
I hope this guide prepared you to do that. I’d love to hear about your setup. Are you growing your palms outside of their ideal temperature range? Or maybe your plant just needs a little extra love here and there? Let us know in the comments section below!
And for more information about growing palms in your home or garden, add the guides to your reading list next:
