Answer: Avocados do well in the mild-winter areas of California, Florida and Hawaii. Some hardier varieties can be grown in the cooler parts of northern and inland California and along the Gulf Coast. The northern limits in California is approximately Cape Mendocino and Red Bluff. Avocados do best some distance from ocean influence but are not adapted to the desert interior. West Indian varieties thrive in humid, tropical climates and freeze at or near 32? F. Guatemalan types are native to cool, high-altitude tropics and are hardy 30 - 26? F. Mexican types are native to dry subtropical plateaus and thrive in a Mediterranean climate. They are hardy 24 - 19? F. Avocados need some protection from high winds which may break the branches.
It is important to choose a cultivar that is hardy in your area. Mexican types are the best choice for colder regions. Plant above a slope for air drainage, or near the house for added protection. In youth, protect with rugs, towels and such spread overhead on a frame. For further protection heat with light bulbs and wrap the trunk with sponge foam. These measures also permit tender cultivars to become established in borderline locations; established trees are much hardier than young ones. The upper branches can also be top worked with hardy Mexican types, which will protect a more tender cultivar on lower branches, as well as serving as a pollinator. Harvest fruit before the frost season begins. Cold-damaged fruit turns black. Avocados are often in bloom at the time of frost and the flowers are killed, but the tree tends to rebloom. This is especially true of Mexican types.
I'd recommend growing Fuerte, Mexicola Grande or Murrieta Green in your new garden.
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