The grapefruit (Citrus × paradisi) is a subtropical, evergreen citrus tree that is grown for its juicy fruits. Grapefruit trees have a rounded top of spreading branches and can grow up to 5-6 m tall. The twigs normally bear short, supple thorns. The leaves are dark green, long and thin with rounded teeth on the margins, and dotted with tiny oil glands. It produces 5 cm white four-petalled flowers, borne singly or in clusters in the leaf axils.

The fruit is largely oblate and ranges in diameter from 10-15 cm, yellow-orange skinned sometimes blushed with pink, with smooth, finely dotted peel, up to 1 cm thick, and aromatic outwardly and with white, spongy and bitter inside. The flesh is segmented in 11 to 14 segments with thin, membranous, somewhat bitter walls, varying in color depending on the cultivars, from white to pink and red. The flavors range from highly acidic and somewhat bitter to sweet and tart. While some fruits are seedless others may have up to 90 white, elliptical, pointed seeds of about 1.25 cm long and are usually polyembryonic. The number of fruits in a cluster can vary from a dozen to as many as 20.

The grapefruit trees grow well in a warm subtropical climate but they are also suitable to be grown indoor or a greenhouse. They will grow best in a place with full sunlight. Temperature differences affect the length of time from flowering to fruit maturity. Humidity contributes to thinness of peel, so a medium humidity is required. Low winter temperatures also may cause a thicker peel for the fruits that will appear in the following year and may even affect the fruit shape. Grapefruits can grow on a wide range of soil types but grow better in a soil that retains water yet drains well. In general, culture of grapefruit is similar to that of the orange, except that they need a wider space to develop well.

Grapefruits ripen slowly over an extended period, storing well on the tree after reaching edible quality, with fruit of a given cultivar harvested from early fall to midsummer. Store grapefruit at room temperature up to a week, or up to 8 weeks in a refrigerator. Leave at room temperature for a couple of hours before eating.

Propagation can be done from cuttings with heel or by sowing seeds. Cuttings can be taken in late summer. Seeds should not be allowed to dry out before sowing. Cover the pot and plant with a plastic bag secured by a rubber band. Place the pot in indirect sunlight or under a fluorescent light. Repot in its regular mix after it has been growing for a while. The plants obtained from seeds are slow in producing flowers and are generally used as stocks for grafting, which can be done early spring, using the splice method. New plants can also be obtained by layering the branches and by air layering, in early summer. Pinch back the plants and mist occasionally with warm water. Prune in the spring.