The limes you're likely to grow are tart limes -- as opposed to the sweet varieties grown in other countries -- and are generally one of three varieties: the Tahitian, Persian or Bearss lime (Citrus latifolia); Key lime, also called Mexican or West Indian (Citrus aurantifolia); or Kaffir lime (Citrus hystix). Most limes grow outdoors in the tropical and subtropical climates of U.S. Department of Agriculture plant hardiness zones 9 through 11. You can grow them indoors in containers in colder climates if you give them enough sun.
In general, lime trees produce most of their fruit from May to October after their third year of growth, although the specific time frame differs by variety. When grown outdoors in warmer climates, they can produce fruit all year. For all limes, ripeness is determined by the color, weight and age of the fruit. Limes turn yellow at full maturity, but you can harvest the Tahitian lime before the color change and you can pick Key limes just after they change color. In general, limes are ripe when they have smooth, glossy skin and a vibrant, dark green or light yellow color. You can always check the ripeness of the limes on a tree by picking one and cutting it open. If it is firm and juicy, your limes are ripe.
Tahitian limes grow to 2 inches in diameter. This seedless variety of lime is ready to pick about three to four months after the tree blooms, with peak production in June, July and August, depending on your climate. Pick these limes when they reach 1 3/4 inches long and have thin, smooth, dark green skin. The flavor of these limes is best just before the color changes from green to yellow.
Key limes are small, acidic limes that are 2 inches in diameter or less when they're mature. This lime variety produces fruit approximately three to four months after the tree blooms, with peak production at the height of summer. Pick Key limes just as they begin to turn yellow for the best flavor.
Kaffir limes are grown mainly for the leaves, rather than the fruit. Use the leaves in Asian cooking to add flavor to chicken and fish. Unlike other lime varieties, kaffir limes have gnarled, bumpy rinds. You can pick the limes in spring, around May, when the fruits turn yellow and drop off the tree. These limes drop from the tree when they're ripe. The fruit of the Kaffir lime can be used as an ingredient in insecticide washes or as an aroma for soaps.