The Chinese Windmill Palm, also known as Trachycarpus fortunei, is a cold-hardy palm tree than can be cultivated as far north as Southern Virginia and Tennessee. This palm is known to withstand temperatures as cold as 0 degrees Fahrenheit for a brief period of time. For the best cold hardiness, you will want your palm to be healthy and a fast grower.
Boosting Windmill Palm Growth
Remove all grass from around your windmill palm in a circle that is as wide as its canopy. Generally, this is how far the root system spreads out. It is important to do this because grass robs nutrients and moisture from your tree.
Amend the soil around the palm. Windmill palms prefer soil that is well draining and fertile. To achieve this, mix a few shovelfuls of organic compost and organic nitrogen fertilizer into the top two inches of the grass-cleared soil. This amendment is all natural and will not burn your plant.
Spread wood mulch around the windmill palm where you removed the grass and added the soil amendments. Mulch improves soil's water retention and works to keep weeds at bay, so your tree's roots won't have competition for water and nutrients.
Clear excess vegetation near your windmill palm. It will grow to between 10 and 20 feet tall and have a spread of 6 to 10 feet wide. Windmill palms grow best in areas that are part shade/part sun, however, they are tolerant of full sun when given plenty of moisture.
Water the palm frequently to keep the soil evenly moist. In periods of hot, dry weather, you will have to water the palm almost daily. Give it a good soaking each time you water it. This will help promote a deep, penetrating root system.
Pull the mulch back every month or so during the growing season and mix in more organic nitrogen fertilizer. You almost can't give plants enough of this in warm summer months.
Protect your windmill palm when the temperature falls below freezing. A simple, yet effective, protection method is to tie your palm's fronds up with bungee cords, wrap the trunk and fronds with C9 Christmas lights (larger bulbs) and then wrap it in burlap. Turn the lights on for heat when the temperature falls below 15 degrees F or when it will not top 32 degrees F for more than a day. Remove all protection when warm weather returns.
Put down 8 to 12 inches of mulch in autumn to insulate the ground if it regularly freezes. Remove in spring.