Tree · Rutaceae
Blood Orange
Citrus × sinensis
Give it full sun and cold winter nights, and the blood orange ripens flesh the color of garnet.
Full sun
Every 7–14 days
USDA 9–11
8–30 ft · 2.4–9.1 m
Overview
The blood orange is a sweet orange with a secret inside. Cut one open and the flesh runs from streaked orange to deep garnet, colored by anthocyanins, the same natural pigments found in berries. It belongs to the citrus family and grows as an evergreen tree, fragrant in flower and heavy with fruit in the cooler months.
What sets it apart is how the color forms. The flesh only reddens when warm days give way to cold winter nights, so the same tree grown in a mild, even climate yields paler fruit. That quirk ties the best blood oranges to places like Sicily, where the chill off Mount Etna deepens the color year after year.
Blood oranges ask for the same care as any sweet orange. They want full sun, free-draining soil, and protection from hard frost, and they reward patience more than fuss. A grafted tree takes a few years to settle in, but once it does it can fruit for decades.
Care
The short version: full sun, well-drained soil, and steady but careful watering that never leaves the roots waterlogged. Feed through the growing season, shelter the tree from frost, and let cold winter nights do the work of coloring the fruit.
Light
Blood oranges want full sun, the more the better, since sun drives both the crop and the sugar in the fruit. They put up with a little partial shade, but a shaded tree flowers less and sets fewer oranges.
Water
Soak young trees about twice a week for the first month, then ease off as the roots reach out. An established tree mainly needs water in dry spells, and the one thing to avoid is waterlogging, which citrus roots cannot stand.
Soil
Plant in well-drained loam, silt, or sandy soil where water never pools. A slightly acidic pH of 5.5 to 6.5 suits the tree, and sharp drainage matters more than the exact number.
Temperature
The tree handles a wide range, from about 41°F to 100°F (5°C to 38°C), but a hard freeze damages leaves and twigs. Cold nights are welcome at fruiting time, though, since they are what turn the flesh red.
Humidity
Average humidity of 40% to 60% keeps the tree happy, so most climates within its range pose no problem. Good airflow matters more than any target number.
Feeding
Feed with a balanced citrus fertilizer such as 8-8-8 with micronutrients through the growing season, roughly February to October. Spreading the feedings across spring through fall keeps growth steady without forcing it.
Pruning
Blood oranges need little pruning. Cut out dead, damaged, or crossing branches and clear any suckers below the graft union, and do it after the fruit ripens, since flowers form on new wood.
Repotting
A container-grown tree needs a larger pot every 2 to 3 years. Roots circling the pot, roots pushing out the drainage holes, or growth that has stalled all tell you it's time to move up a size.
Size & spacing
Out in the ground a blood orange can reach 8 to 30 feet (2.4 to 9 m) tall with a canopy spreading 8 to 15 feet (2.4 to 4.5 m) wide. Give it that much open room so the branches get full sun and air moves freely through the tree.
When to plant
Blood oranges run on a winter clock. Plant young trees in spring once frost has passed, watch for fragrant white flowers later that spring, and pick the ripe fruit from winter into early spring, after a run of cold nights has turned the flesh red.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Spring, after danger of frost has passed
- Harvest: Fragrant white flowers in spring; blood oranges ripen winter to early spring (about December to April), developing deepest flesh color after cool nights
Hardiness
USDA hardiness zones: 9–11
Temperature: down to -7°C
Troubleshooting
Most blood orange trouble traces back to insects, cold, or one serious disease. Catch the early signs and you can save the tree, or at least slow the damage. Match what you see below, then act before it spreads.
Patchy yellow leaves and lopsided, bitter fruit
This is citrus greening, also called Huanglongbing, and it is the worst thing that can happen to a citrus tree. A tiny insect, the Asian citrus psyllid, carries it from tree to tree, and there is no cure once a tree has it. Pull and destroy the infected tree, plant only certified disease-free stock, and keep the psyllid in check before it ever arrives.
Fix:
- Remove and destroy infected trees
- Control the Asian citrus psyllid vector
- Plant certified disease-free stock
Leaves dropping and twigs dying back after a cold snap
This is freeze damage. A hard frost leaves the foliage water-soaked, then brown, and the leaves fall while the twig tips die back. Cover the tree during freezes, give it the warmest spot you have, and wait until new growth returns in spring before you cut out any dead wood, since the bare twigs often push fresh leaves once the weather turns.
Fix:
- Provide cold protection during freezes
- Prune out dead wood only after new growth resumes in spring
Black sooty film over leaves and fruit
The black coating is sooty mold, and it grows on the sticky honeydew left behind by aphids, whiteflies, scale, or mealybugs. The mold itself does little harm and wipes right off, but it tells you sucking insects are feeding underneath. Treat the bugs with horticultural oil and rinse the leaves clean, and the mold has nothing left to live on.
Fix:
- Control the honeydew-producing insects with horticultural oil
- Rinse foliage to remove mold
Toxicity
The juicy flesh is a kitchen favorite, but the rest of the tree is not for animals. The peel, leaves, and seeds hold essential oils and psoralens that upset a pet's stomach and can irritate skin. Keep cats, dogs, horses, and grazing animals away from the rind, foliage, and prunings.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds
Safe for
People
Cats Mild
A cat that chews the peel or leaves may drool, vomit, or get loose stools and act low for a while. The peel oils can also leave the skin red and itchy.
Dogs Mild
Expect an upset stomach, vomiting, or diarrhea if a dog eats the rind or foliage, and the oils sometimes irritate the skin on contact.
Horses Mild
The ASPCA lists sweet orange as toxic to horses, and the same peel oils and psoralens upset the gut. Keep prunings and windfall peels out of the paddock.
Rabbits Caution
The peel and leaves carry the same irritating oils, so they are not a safe nibble. A small piece of the flesh now and then is fine, but skip the rind and foliage.
Livestock Caution
Goats, sheep, and cattle can handle small amounts of pulp, but a belly full of bitter peel and leaves brings on digestive trouble. Don't let them browse the tree or its trimmings.
Birds Caution
A bit of the juicy flesh is a treat many birds enjoy, but the oily peel and pith are best left off the menu.
People Flesh safe
The juicy flesh is a kitchen favorite and perfectly safe to eat. Handling a lot of peel can leave sensitive skin tingling in sunlight, thanks to the psoralens in the oil.
The fleshy fruit pulp is edible, but keep peels, leaves, seeds, and concentrated peel oils away from pets.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
Three blood orange cultivars turn up again and again, each with its own balance of color, sweetness, and season. These are the ones worth knowing by name.
Moro
Moro carries the deepest, most reliable crimson-to-burgundy flesh of the three, with the highest anthocyanin content and a berry flavor that hints at raspberry.
Tarocco
Tarocco is Italy's most widely grown blood orange, sweet and low in acid with almost no seeds and flesh that ranges from orange to red.
Sanguinello
Sanguinello is a late-season Spanish cultivar with few seeds and moderate red color that holds well on the tree long after it ripens.
How to propagate
Blood oranges are grown almost entirely by grafting, which copies a prized tree exactly. Seed works in a pinch, but it asks for years of patience and gives you no promises.
GraftingDemanding
Spring to summer when the bark slips · 1 to 2 years to a sellable tree; about 3 to 5 years to fruiting
Grafting is how nurseries grow nearly every blood orange. You join a bud of the chosen cultivar onto a rootstock in spring or summer, while the bark still slips, which keeps the fruit true to type and borrows the rootstock's disease and cold tolerance. It takes skill, and you're looking at 1 to 2 years to a tree worth selling and 3 to 5 years before it fruits.
SeedModerate
Spring · Several years; many seedlings come true due to nucellar embryony but are slow to fruit
Growing from seed is easy enough to try in spring, but nurseries skip it for good reason. Many citrus seeds come true to the parent through a quirk called nucellar embryony, yet the seedlings throw thorny juvenile growth and take several years to fruit. Expect a slow, unpredictable plant rather than a quick copy of the tree you started with.
Myths
Blood oranges are a man-made cross or a genetically modified fruit.
The red color comes from anthocyanins, the same natural pigments that redden berries and red cabbage. A blood orange is just a pigmented form of the ordinary sweet orange, Citrus x sinensis, that arose on its own with no lab or crossbreeding behind it.
Blood oranges need a hot tropical climate to turn red.
The opposite is closer to the truth. The flesh reddens only with a swing between warm days and cold nights, which is why the deepest color comes from places with chilly winters, like the slopes around Mount Etna in Sicily, rather than from steady tropical heat.