Delicious and easy to grow, Citrus × aurantiifolia (Key Lime) is a spiny evergreen shrub or small tree, prized for its rounded fruit, 2-3 in. across (4-6 cm), with juicy green pulp. Green and glossy when immature, the fruit turns pale-yellow when ripe. It is aromatic, juicy, very acid and flavorful. Valued for its unique flavor, it lends itself to many culinary uses. It is smaller and seedier, with a higher acidity, a stronger aroma, and a thinner rind, than that of the Persian lime (Citrus x latifolia). The slightly fragrant flowers are beautiful with their 5 long white petals, with a light purple tinge on the margins, and their bundled white stamens adorned with yellow anthers. They shine against the pleasantly aromatic, evergreen foliage of glossy green elliptic leaves. Flowers and fruit appear throughout the year, but are most abundant from late spring to early fall in the Northern Hemisphere. Exceedingly vigorous, Key Lime boasts many slender, spreading branches, armed with short, stiff, sharp spines.

The common name is derived from its association with the Florida Keys, where it is best known as the flavoring ingredient in Key lime pie.

• Grows up to 6-15 ft. tall (180-450 cm) and 2-4 ft. wide (60-120 cm).
• A full sun lover, this plant is easily grown in fertile, well-drained soils. Add sand and ground bark to potting mixes and garden soils. Needs water regularly but cannot stand flooding or saturated soils. Fertilize four times annually with an all-purpose formula or a specialty fertilizer made for citrus. Mulch plantings in beds or pots with 1 in. (2.5 cm) of organic material such as ground bark.
• Key Lime is more sensitive to cold than the lemon. It thrives in a warm, moist climate, but nevertheless tolerates drought better than any other citrus fruit. Where winters are frost-free, choose a site outdoors in full sun. Elsewhere, grow it indoors in a warm, sunny room when temperatures are below 40ºF (4ºC) and move it outdoors to a sunny spot.
• Shrubby by nature, key limes can be trained into a small tree with selective pruning in late winter or early spring.
• Generally disease free. Keep an eye out for glasshouse red spider mite, glasshouse whitefly, scale insects and mealybugs under glass.
• Propagate by air layering, seeds, and rooting tip cuttings.
• Toxic to dogs, toxic to cats, toxic to horses.
• Native to tropical Asia