Palms Can Grow in Northern States!
Palms are grown all over the world. Canada serves a Northern reference point and many types of palm trees can grow there. The main factors affecting hardiness are the minimum winter temperature, the number of hours of cold every winter, the amount of heat every summer, and the relative wetness or dryness of the climate. In general, palms are not particularly hardy. Many are actually injured by a single freezing night. Others can withstand zero degrees F for short periods without damage.
The U.S. Department of Agriculture has developed a system of cold hardiness zones based on the average annual minimum temperature. The zones that are considered “borderline” are the following:
- 10 to 15 degrees F = Zone 8a
- 15 to 20 degrees F = Zone 8b
- 20 to 25 degrees F = Zone 9a
- 25 to 30 degrees F = Zone 9b
How do I get a palm established in a “borderline” area?
Most hardy palm growers recommend protecting the palm from the climate for at least the first two years that it is in the ground. The palm should be mulched with a deep layer of fall leaves or other material. The palm can then be wrapped in burlap, bubble plastic, a spun landscape material such as “remay” or “garden blanket”, or even an old sheet or blanket. If you use a non-porous material such as plastic, it is best if air space is left between the palm and the material. This air space may not be needed if you only protect the palm during cold spells. It is best to stay with palms that grow in your zone.
The hardiest arborescent (trunking) palm is the Windmill Palm – Trachycarpus fortunei. They are grown as far north as parts of British Columbia in Canada. They have a fuzzy trunk which can grow twenty feet tall. They do not need a hot climate, and seem to thrive in cool, moist weather.
Sabal palmetto (Sabal palm, Cabbage palm) is the state tree of Florida and South Caroline. It has been known to survive between zero and five degrees when well-established . It cannot survive these temperatures on a regular basis, and is probably best rated as a zone 8a. It is a large fan palm which takes many years to form a trunk. It can be found in the wild as far north as Bald Head Island, North
Carolina, near Willmington.
Chamaerops humilis (European fan palm/Mediterranean fan palm) is quite hardy in areas which have a dry climate. It is usually rated as a “zone 8” palm. In areas with wet winter soil (like the eastern U.S. and the Pacific Northwest). It seems to be less hardy. Planting this palm in a well-drained bed (such as a bed prepared for a cactus garden) may help it survive in these areas.
Washingtonia robusta, Washingtonia filifera, and Brahea armata are western desert palms which are fairly hardy in their native environment (zone 8, zone 9a).
Phoenix canariensis is a large date palm which can grow in zone 8b areas.