Citrus x paradisi

One of the newest citrus fruits, grapefruit is a small evergreen tree in the Rutaceae family that grows 10 to 30 feet tall and just as wide and usually has sharp thorns on its twigs. Grapefruit are grown in tropical, sub-tropical climates around the world.  In the 19th century, it was found growing in Barbados, and in most of Jamaica.  Originally, it was thought that grapefruit was a mutation of the pumelo.  In the mid 1900s, citrus specialists decided it was an artificial hybrid cross between an orange and a pumelo.  The fruit is pale yellow (when ripe) with areas of pink and has several varieties with pale yellow, nearly white, pink, or even deep red pulp. The fruit is very juicy, and the juice is acidic. In cooler zones it can be grown in a container that can be overwintered indoors.

Grapefruit requires full sun and cannot tolerate shade.  It prefers a deep, well-drained but moist, loamy soil.  Do not overwater.  Established plants are drought tolerant.  It prefers a pH of 5 - 6 and is sensitive to high salinity.  Grapefruit will tolerate a neutral or alkaline pH range as well with proper fertilization.  They need very little pruning, only to keep its shape or to remove dead or damaged branches.  Grapefruit are propagated by grafting as seeds will not produce fruit true to type.

The leaves, flowers and the fruit are all used for medicinal purposes.  Grapefruit are high in Vitamin C which is good for the body.  A concentrate prepared from the flowers can be taken to overcome insomnia.  The fruit and its juice can improve an appetite and aid in digestion.  Also, as a cardiotonic. The pulp is considered an effective aid in the treatment of urinary disorders. Leaf extractions have shown antibiotic activity.

Plant outside in full sun for year-round enjoyment in tropical or subtropical climates or put in a planter for movement inside when the weather turns cold.  If you choose to leave some of the fruit on the tree throughout the winter, it will continue to ripen on the tree and become sweeter.  Be aware that in doing so, it may reduce the size of the following year's harvest.

Insects, Diseases, and Other Plant Problems:  This plant can cause contact dermatitis in some people.  Many of the same insects and diseases affecting the sweet orange also affect the grapefruit.  The tree is highly susceptible to citrus canker and several viruses including crinkly leaf virus, psorosis, tristeza, xyloporosis, and infectious variegation. 

The Clemson Cooperative Extension Home and Garden Information Center has a factsheet on common citrus insect and related pests.