CITRUS x paradisi
Plant Common Name
The common grapefruit takes its name not from its flesh, which is juicy and acidic, but from the way the fruit grows in hanging clusters. This evergreen tree is thought to be a hybrid of the Asian pummelo, which has much larger fruits, and the sweet orange, a native of China. It arrived in the United States around 1853 from the Caribbean.
Grapefruit trees are large, evergreen and sometimes have short, soft thorns on their twigs. The fragrant, thick, glossy leaves are broadly oval, dotted with small oil glands and usually have winged petioles (leaf stems). The flowers are born from late winter to early spring and may be clustered or solitary in the leaf axils (joint between the leaf and stem). Flower buds are red or purple-hued and open to reveal white, four-petaled, fragrant blooms. From these come highly variable, large, fragrant fruit that are round to pear-shaped and generally yellow. They have thick leathery skin dotted with oil glands and juicy, variously tinted, acid flesh with or without many seeds. Fruits ripen in the late fall through winter and are harvested by hand as they mature.
Like most citrus, the trees are cold sensitive and prefer locations with warm, dry winters, and long warm to hot summers. If fact, trees can only tolerate a few degrees below freezing for a few hours. Grapefruits require full sun and are tolerant of most soils, even nutrient-poor soils, with ample drainage. Though moderately drought tolerant once established, they must have regular applications of water for good fruit production.
Grapefruit trees have large rounded canopies and require plenty of space, more than orange trees, for good growth. They are heavy feeders needing regular applications of fertilizer. There are a multitude of varieties available, some ideal for commercial production and others best suited to backyard orchards. Most are grafted on to rootstocks, which impart tolerances to local soil, pest and climate conditions as well as preserving the desired varietal characteristics.
Though large, these trees can be trained to be more compact via grafting and pruning. Those on dwarfing rootstocks make great tub or conservatory specimens. No backyard orchard in subtropical and tropical zones is complete without at least one prolific and long-lived grapefruit tree.