Do you live in an area of freezing winter temperatures but long for the look of the tropics in your garden? Don’t despair. You can have the best of both worlds.
There are dozens of species of cold-hardy palms, the signature plant of beach vacations and tropical getaways, that will grow in states well above the Sun Belt. In fact, there are a few that can survive temperatures below zero.
Many are native to high elevations in distant lands, such as Trachycarpus fortunei (the Windmill Palm, which is from China). A few are native to the Southeastern United States, including Rhapidophyllum hystrix (Needle Palm), Sabal palmetto (Cabbage Palm) and Sabal minor (Dwarf Palmetto). Perhaps best of all, there are one or more palms that will grow in all but a handful of states.
If you are an adventurous gardener who would like the way snow could turn a palm tree in your garden into a conversation piece, here is a guide to help you choose and care for cold-hardy palms.
Matching plant temperature minimums and your plant hardiness zone is a good place to start. However, if you have a protected microclimate, it may be possible for you to cheat a little on your hardiness zones. Also bear in mind that hardiness zones have been creeping northward (i.e. getting warmer), although the change in zones hasn’t gained wide acceptance among plant enthusiasts.
How to site palms
All palms want a well-drained site. If in doubt about whether a palm can survive your winters, plant it in a protected area – preferably one with a southern exposure.
How to grow
Palms, like almost any tree, are most vulnerable in their first three years. Your best chance to help a young palm live through these initial winters is to protect it from the elements.
Some might suggest the best way to do that is to put a wire basket around it and fill the basket with leaves to serve as insulation. That may work for elephant ears and bananas (which go dormant), but is not such a good idea for palms, which are evergreen. Instead, cover a young tree with an old blanket or sheet to help insulate it. Once the plant has established some trunk size, a protective covering should not be needed.
Other factors that can affect a palm’s ability to survive low temperatures include:
How long cold weather lingers.
Daytime high temperatures.
How much sun and wind the plant receives.
Palms have several other cultural requirements that should be remembered:
They prefer neutral soils.
Their roots should be left as undisturbed as possible.
Regular watering during the summer and regular fertilization will make them happy.
Pruning is important
Pruning palms can be tricky for people who are not familiar with the growth habit of these trees. Only the dead fronds hanging straight down should be cut off. But, instead of pruning the frond all the way back to the trunk, a short piece of it should be left attached to the trunk. Leaving a piece of frond a few inches long helps to minimize damage to the trunk, which can be hard for palms to recover from.
Also, flower and fruit stalks can be removed. This is especially beneficial when a plant is young because it helps maintain the health of the plant and allows it to continue to grow vigorously.
For more information
Good resources include the book "Betrock’s Cold Hardy Palms" and the Palm Society’s website.