A key lime tree that produces fruit is a coveted possession, so despite its love for warm climates, people want to grow it outside its natural habitat. Key limes are yellower than the more common Persian lime, and people prize the fruit not only for making key lime pie, mousse, coulis, ice cream, sorbet, pudding, yogurt, cookies, tarts, and other desserts, but also as a compliment to seafood such as salmon, swordfish, striped bass, shrimp, lobster, and red snapper. It is also used in martinis, mojitos, ginger cup, and in Ke Ke Beach Key Lime Cream Liqueur, whence its nickname, Bartender’s Lime.
The key lime is in the Rutaceae family and is called Citrus aurantifolia, which means golden-leaved citrus. The fruit is 1 to 2 inches (2.5 to 5 cm) in diameter and has a unique flavor among the limes. In the United States, it is closely associated with the Florida Keys, hence its popular name, but it is also known as Tahitian lime or West Indian lime—Mexican lime is actually a different species.
The key lime is native to Southeast Asia. It apparently traveled from there to North Africa, from there to the European countries on the Mediterranean, and was brought by Spanish explorers to the Caribbean, including the West Indies and the keys of Florida. Later, it spread to Mexico, northern Florida, and California. Today key limes that are sold as food are grown in Texas, California, Mexico, and Central America.
There are several ways to grow a key lime tree, partly depending on where you live. If you live in USDA Zone 10 or higher, you can grow definitely grow a key lime tree outdoors, but experts vary in recommending it as an outdoor plant for Zone 9: some do and some don’t. North of Zone 9 or 10, container planting is recommended. When it is warm enough, you can move the key lime tree outside if you wish. Alternatively, you can keep your Key lime tree indoors year round. Dwarf Key Lime trees are available, which can make shifting the container around easier.
Suggestions for container planting include lining the bottom of the container with stones or pottery shards, and using soil that drains well. Experts warn that if the trunk is below the soil line, it may rot. Key lime trees prefer moist soil and misting. They prefer a southern exposure, and may need additional light if they can’t be placed in full sun. The best temperature for a key lime tree is 70ºF (21ºC) during the day and 54ºF (12.2ºC) at night.