Avocados are native to Mexico and Central America; in most cases, they grow in U.S. Department of Agriculture Plant Hardiness Map zones 9 to 11. Avocado plants are semitropical and grow the avocado fruit, which comes in a few different varieties. Alabama ranges from USDA plant hardiness zones 7 to 8, which can be a little too cold for most kinds of avocados. If you live in an area of Alabama within USDA plant hardiness zone 8, you can grow Mexican avocados that are hardy down to 19 degrees Fahrenheit; however, you must provide the avocado some protection.
Determine the best location for your avocado tree. Choose an area of your yard that faces the south or the west and is not prone to freezing. Select a location near a fence or wall for added protection from the wind. Work 12 to 18 inches of compost into the soil to a depth of about 2 feet. Avocados need full to partial sun and well-drained soil to thrive.
Plant the tree in the spring once the weather warms to about 70 degrees Fahrenheit. Dig a hole for the avocado tree about 2 feet deep and 3 feet wide. Place the avocado tree into the hole and fill the hole with soil. Water the tree well for 15 minutes so the soil settles around the tree's roots.
Add 3 to 4 inches of mulch around the base of the avocado tree. Water the tree for 15 to 20 minutes every one to two weeks if there has been no rainfall.
Sprinkle 1/4 lb. of 10-10-10 fertilizer around the base of the one-month-old tree. Increase the amount of fertilizer to 1 lb. when the tree is a year old. Fertilize the tree every year in the spring before it blooms.
Wrap the avocado tree's trunk in blankets and tie the blanket closed with twine. Drape the rest of the canopy with blankets and place one or two space heaters around the base of the tree on cold nights that drop below about 20 degrees Fahrenheit. Remove the blankets when the weather moves above freezing.
Harvest the fruit once it is fully grown. The avocados will ripen after one to two weeks.