Grapefruit

Tree facts

Scientific name

Citrus × paradisi

Origin

Barbados (West Indies)

Tree size

15–30 ft; can be kept at 12–15 ft

Growth rate

Medium

Sun

Full sun, at least 6–8 hours

Soil

Any soil that drains well, including sand. Never waterlogged; plant high where water stands.

Soil pH

6.0–7.5

Pollination

Self-fertile; one tree is enough

Cold hardiness

Leaves are damaged near 26–28°F; fruit freezes after a few hours at 28°F

USDA zones

9b–11

Years to first fruit

3–4 for a grafted tree

Season

Nov–Apr

Water

About every 7 days once established, without rain; more in heat, in pots and while young

Feeding

About every 60 days, Feb–Oct

Pruning

Mar–Apr

Taste

Tart-sweet and juicy with a bitter edge; red types are sweeter

Nutrition

High in vitamin C, with lycopene and beta-carotene in red and pink types

Is grapefruit safe to eat? Edible and toxic parts

What you can eat

• Segments and juice
• Peel, candied or in marmalade

Toxic parts and cautions

• Toxic: Grapefruit interacts with many prescription drugs. Its furanocoumarins block CYP3A4, a gut enzyme that breaks down medicines, so drug levels can climb dangerously high, and one serving can last a day or more. Affected drugs include some statins (simvastatin, lovastatin, atorvastatin), some blood-pressure and heart-rhythm drugs, and some anti-anxiety, transplant and other medicines. Pomelos, Oro Blanco and sour (Seville) oranges do the same. If you take any regular medicine, ask a pharmacist before eating it.
• Good to know: Citrus juice or peel oil left on the skin in strong sun can cause a burn-like rash that darkens the skin for weeks (phytophotodermatitis). Wash your hands after peeling or squeezing fruit outdoors.

Pets: The peel, leaves and seeds contain essential oils (limonene, linalool) and psoralens that can cause vomiting, drooling and skin irritation in dogs and cats. A bite of the flesh is usually harmless.

How to eat and enjoy grapefruit

• Halved and eaten with a spoon
• Broiled with brown sugar
• Fresh juice
• Salads with avocado or shrimp
• Paloma cocktail (Mexico)
• Candied peel and marmalade

Grapefruit varieties (7)

• Duncan

  The oldest known Florida grapefruit: very seedy, but with superb, rich flavor.

  Origin: Florida, about 1830 · Taste: Rich, tart-sweet · Season: Dec–Mar · Size: Large

  Somewhat more cold-hardy than other grapefruit.

• Flame

  A seedless red grapefruit selected in Florida that keeps its red color well in Florida's climate.

  Origin: Florida (USDA), 1987 · Taste: Sweet-tart · Season: Nov–Apr · Size: Large

• Marsh · also Marsh Seedless, White Marsh

  The classic seedless white grapefruit, with pale yellow flesh and a sharp, refreshing flavor.

  Origin: Florida, 1860s · Taste: Tart, refreshing · Season: Dec–May · Size: Large

  Holds well on the tree into late spring.

• Oro Blanco · also Oroblanco

  A cross of pomelo and white grapefruit with pale, very sweet, low-acid flesh and a thick rind.

  Origin: California (UC Riverside), 1980 · Taste: Sweet, mild, no bitterness · Season: Nov–Feb · Size: Large

  It carries grapefruit's drug interactions too.

• Rio Red

  A deep red, seedless Texas grapefruit and a more vigorous alternative to Star Ruby.

  Origin: Texas, 1984 · Taste: Sweet, low acid · Season: Nov–Apr · Size: Large

  The main red grapefruit grown in Texas.

• Ruby Red · also Ruby, Redblush

  A red-blushed, pink-fleshed sport of the Thompson grapefruit, found in the Rio Grande Valley.

  Origin: Texas, 1929 · Taste: Sweet-tart · Season: Nov–Apr · Size: Large

  The flesh fades toward pink as the season goes on.

• Star Ruby

  A seedless grapefruit with intensely red flesh, bred in Texas from irradiated seed.

  Origin: Texas, 1970 · Taste: Sweet, rich · Season: Nov–Apr · Size: Medium to large

  A fussy tree: sensitive to cold, some herbicides and nutrient shortages.

Pests and diseases to watch for

• Whiteflies

  Clouds of tiny white flies when a branch is shaken; yellowing leaves and sooty mold.

  What to do: Insecticidal soap or horticultural oil on leaf undersides.

• Citrus greening (HLB)

  Blotchy, uneven yellowing that isn't the same on both halves of a leaf; small, lopsided, bitter fruit that stays green at the bottom; twig dieback.

  What to do: There's no cure. Keep the tree well fed with a complete citrus fertilizer and micronutrients to slow decline.

  A regulated disease in Florida, Texas, California and elsewhere. If you suspect it, contact your county extension office or the state agriculture department.

• Citrus canker

  Raised, corky brown spots with a yellow halo on leaves, twigs and fruit; fruit may drop early.

  What to do: Copper sprays protect new growth and young fruit.

  Regulated in several states. Report suspected cases to your extension office.

• Citrus leafminer

  Silvery, winding tunnels in young leaves, which curl and twist.

  What to do: Mostly cosmetic on mature trees; leave them be.

• Phytophthora root rot

  Small, pale, wilting leaves, thin canopy and branch dieback; roots are black and brittle instead of white.

  What to do: Water less and improve drainage.

• Caribbean fruit fly

  Ripe fruit with tiny puncture marks; maggots inside and soft, rotting spots.

  What to do: Pick fruit slightly early and ripen indoors.