Windmill palms (a.k.a. Chusan Palms) are native to a large region of southeastern Asia, ranging from India to China, and are found in mountainous elevations above 6,500 feet. They can face extended periods of below-freezing weather as well as heavy snow in their native habitats.
All members of the trachycarpus genus share some common characteristics, such as a tall, narrow trunk, and a compact crown featuring a dense group of palmate leaves. The old, dead leaves can form a skirt around the top of the trunk. They often grow up to 30 feet when planted in warmer temperate regions of the United States, and can grow even taller in their native habitat.
Trachycarpus Fortunei (Windmill Palm)
One notable characteristic of trachycarpus fortunei is that it prefers mild summers. In fact, it will not grow in hot, tropical areas, but it seems to grow well throughout most of the southern United States, and up the west coast as far north as Vancouver.
Windmill palms can be grown to zone 7b without significant winter protection. In a sheltered site or with winter protection, windmill palms can be grown through zone 6, although defoliation may occur during cold winters. With care, the palms will usually recover from defoliation. The sensitivity of trachycarpus fortunei to defoliation may decrease as the palm becomes older and more established.
Mulch heavily. Gradually remove the mulch in spring. Site in a favorable wind-protected exposure, such as the south side of a wall or building. Windmill palms are prone to fungal and bacterial crown rot under wet winter conditions. Spraying the foliage and crowns several times during the winter with a fungicide/bactericide spray will help prevent crown rot.
Windmill palms prefer moist, well-drained, organic soil. Planting in partial shade is recommended, especially in areas with hot summers.