Modern citrus fruits, according to genetic analysis, are complex hybrids arising
from mandarin, pomelo, and citron ancestors, refined by more than four thousand years of
cultivation. The grapefruit was first identified in Barbados, and resulted from an accidental
cross between Sweet Orange and Pomelo. Many cultivars, and hybrids of grapefruit with other
citrus, are now available.
Lifespan: 35-50 productive years.
Leaf retention: Evergreen.
Growth rate: Moderate.
Mature Size: 15-20' high and as wide.
Flowers: White, four petals, fragrant.
Self-fruitful: All cultivars self-pollinate.
Years before fruiting: 3 for grafted trees, 10 for those grown
Fruit: Round to oval, a thick yellow rind, with flesh that can be
white, pink or red, aromatic, and slightly bitter. The red fleshed cultivars tend to be sweeter.
Months for fruit to ripen: 10. Grapefruit may be allowed
to stay on the tree after ripening until May.
Storage after harvest: Up to one week at room temperature or
several weeks refrigerated.
Leaves: Glossy dark green, lance-shaped, smooth margins.
Stems: There are short thorns on the twigs. The bark is prone
to sunscald if not shaded by the leaves, especially in higher temperatures.
Roots: Usually grafted onto a special rootstock that is pest
resistant and adapted to the local climate.
Cultivars of Note:
'Rio Red' - Sweet red flesh, few seeds.
'Oro Blanco' - Sweet yellow flesh, few seeds, easy to peel,
a hybrid of grapefruit and pomelo.
Wildlife: Attracts bees, insects, birds, and is a
food plant for the Giant Swallowtail butterfly caterpillar – see Pests, below.
Mammals may strip the bark off of young trees, consume fallen fruit, or climb the tree to eat
Toxic / Danger: Possible thorns. Grapefruit can interact with
many medications, including chemotherapy, making them more, or less, effective and throwing off the
Origin: A natural hybrid first recognized in Barbados.
Cultivation and Uses
USDA hardiness zones: 9-11. Somewhat less cold-hardy than oranges.
Chill hours: None.
Heat tolerant: Yes.
Sun: Full sun.
Drought tolerant: Depends on the rootstock. Drought will damage the
Water after becoming established: Deeply, monthly in winter to weekly
in summer, from the trunk to just beyond the canopy. Grapefruit trees require 20% more water than orange trees
of the same size. Young trees need watering more often than older trees even though older trees consume
more water. A sign of insufficient water is the leaves turning dull and curling inward from the edges.
Soil: Well drained, can be mixed with aged compost and sand,
pH 5.6-8.5 (acidic to alkaline).
Fertilize: Do not fertilize the first two years.
Apply an organic fertilizer every month from mid-February to early October. Apply citrus micronutrients
three times a year, in February, May and August. Do not fertilize after October to keep the plant from
producing new growth that will be harmed by early frost.
Mulch: Keep all mulches 1' away from the base of the trunk.
Keep grasses and vegetation 3' away from bud union on trunk.
Planting: Place the root ball so that it is slightly higher than the
surrounding soil and not at the bottom of a large basin that will cause overly wet soil during rains
and subsequent root rot.
Prune: Remove sprouts growing on the trunk under the bud union
as they occur because these are from the wrong plant. Remove dead, damaged, crossing and weak branches in
late winter. When shaping into a tree, unshaded trunks and branches should be painted with a tree trunk
paint to protect against sunscald.
Litter: Dropped fruit must be picked up immediately to avoid
attracting wild animals.
Propagation: Cuttings grafted onto disease resistant rootstock
adapted to the local climate. Trees grown from seed are usually true to their parent tree characteristics.
The Giant Swallowtail Butterfly caterpillar. This larvae
resembles bird poop and has white and black and/or brown splotches. On a large plant it will cause no harm.
On a small plant, relocate it to a large citrus.
See Citrus: Diseases and Disorders
Uses: Ornamental, edible fruit.
The fruit and flowers pictured are 'Oro Blanco'.
Do you have additional information or a different
experience for this plant that you would like to share?
Email firstname.lastname@example.org. All contributions
are welcome and appreciated.