A member of the Rue family. Modern citrus fruits, according to genetic analysis,
are complex hybrids arising from mandarin, pummelo, citron and pepeda ancestors,
refined by more than four thousand years of cultivation. The grapefruit was
first identified in Barbados, resulting from an accidental cross between Sweet
Orange and Pummelo. Many cultivars and hybrids of grapefruit with other citrus
are now available.
35-50 productive years.
15-20' high and as wide.
White, four petals, fragrant.
All cultivars self-pollinate.
Years before fruiting:
3 for grafted trees, 10 for those grown
Round to oval, thick yellow rind, flesh can be slightly
bitter, white, pink or red, aromatic. The red fleshed cultivars
tend to be sweeter.
Months for fruit to ripen:
Storage after harvest:
Glossy dark green, lance-shaped, smooth margins.
Short thorns on twigs. Bark is prone to sunscald if not
shaded by leaves, especially in higher temperatures.
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 pummelo.
Attracts bees, butterflies, birds, mammals, including
those which climb the tree to pick the fruit.
Toxic / Danger:
Possible thorns. Grapefruit can interact with
many medications, including chemotherapy, making them more, or less,
effective and throwing off the prescribed dose.
A natural hybrid first recognized in Barbados.
Cultivation and Uses
USDA hardiness zones:
9-11. Somewhat less cold-hardy than oranges.
Depends on rootstock. Drought will damage fruit crop.
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 leaves turning dull and curling inward
from the edges.
Well drained, can be mixed with aged compost and sand,
pH 5.6-8.5 (acidic to alkaline).
Apply a citrus fertilizer mid-February, May, and early October.
Follow directions on package.
Or, if using organic fertilizer, apply every month from mid-February to
early October. Do not fertilize after October to keep the plant from producing
new growth that will be harmed by early frost.
Keep all mulches at least 1' away from the base of the trunk.
Keep grasses and vegetation 3' away from bud union on trunk.
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.
Remove sprouts growing on the trunk under the bud union
as they occur. Remove dead, damaged, crossing and weak branches in
late winter. When shaping into a tree, unshaded trunks and branches
should be painted with a white tree trunk paint to protect against sunscald.
Dropped fruit must be picked up immediately to avoid attracting wild animals.
Cuttings grafted onto disease resistant rootstock
adapted to the local climate. Trees grown from seed are usually true to
their parent tree characteristics.
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 or kumquat.
Citrus: Diseases and Disorders
Ornamental, edible fruit.
The fruit and flowers pictured are 'Oro Blanco'.
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