The key lime tree, also known as Mexican lime, is a citrus variety native to the Indo-Malayan area. Key limes are hardy to plant in the subtropical climates of southern Florida, but also grow in northern Florida when given cold protection. The tree produces glossy leaves with small, bright-green fruit that adds a touch of tartness to desserts and drinks. The key lime tree reaches a height of 12 feet with a branch spread that needs 25 feet of space between trees.
Select a planting location for the key lime tree that has nutrient-rich, well-draining soil. The site should receive at least six hours of direct sunlight daily. Test the soil pH to verify it is 6.0 to 8.0. Amend the planting area with ground rock sulfur to raise the pH or limestone to lower the pH.
Plant the key lime tree in a hole that is two times the size of the root ball and the same depth. Mix an equal part of organic compost into the removed soil to increase the nutrient value and moisture retention since Florida soil is sandy.
Water newly planted trees two to three times a week for the first month. Continue to supply water to the tree during the first growing season when the soil becomes dry to 1 inch below the surface. Water established lime trees when the weekly rainfall is less that 1 inch during periods of drought.
Fertilize the key lime tree each spring with a 2-8-10 fertilizer to promote fruit production. Contact your county university extension office to have a complete soil test completed on the planting area. The results will give recommendations for an appropriate fertilizer application based on the soil characteristics.
Apply a 3- to 4-inch layer of organic mulch around the drip line of the tree. The drip line is the ground area from the trunk of the tree to the tip of the lower branches. Leave a 6-inch gap from the trunk of the tree to the start of the mulch.
Prune key lime trees each spring to remove dead and damaged branches. Remove branches that sprout on the lower trunk below the main branches.
Provide cold and frost protection for key lime trees growing in northern Florida. Wrap the trunk and crown of the tree when the temperature drops below 26 degrees Fahrenheit.