Tree · Rutaceae
Yuzu
Citrus junos
Hardiest of the true citrus, yuzu trades easy fruit for patience and a sheltered, sunny spot.
Full sun
Every 7–14 days
USDA 8–11
6–18 ft · 1.8–5.5 m
Overview
Yuzu is the cold-hardy citrus that lets gardeners well outside the orange belt grow their own fragrant fruit. It comes from East Asia, where the knobbly yellow fruit flavors everything from ponzu sauce to winter baths, and the aromatic peel and tart juice are what make it worth the wait. The tree itself is a thorny evergreen that holds its leaves year round.
Patience is the trade-off. Yuzu grows at a moderate pace and a grafted tree takes a year or two to fruit, while a seedling can take several. It earns its keep with toughness, taking temperatures down toward 14°F (-10°C) once established, far colder than most citrus will bear.
Grown in the ground in zone 8 and warmer, or in a large pot that moves under cover for hard freezes, yuzu rewards steady care. Give it full sun, free-draining soil, and shelter from the worst cold, mind the long thorns when you prune, and the tree will hand you fruit every autumn.
Care
The short version: full sun, slightly acidic well-drained soil, and water once the top of the soil dries. Feed monthly through the growing season, shelter young trees from hard frost, and wear thick gloves around the thorns.
Light
Yuzu wants full sun, ideally six or more hours a day, to ripen good fruit. It will take partial shade, but the tree grows leggier and crops lighter where the light runs thin.
Water
Let the top inch or so (3 cm) of soil dry before watering, then water deeply, roughly every 7 to 14 days. Trees in pots dry out faster and need it more often, while in winter you should ease off and let the tree rest.
Soil
Plant in well-drained, slightly acidic sandy loam with plenty of organic matter worked in. A pH of 6.0 to 7.0 keeps the roots taking up iron and the other micronutrients citrus depends on.
Temperature
Yuzu handles a wide range, from about 14°F to 95°F (-10°C to 35°C), the toughest cold tolerance of any true citrus. Even so, young trees need frost cover, since the hardiness builds only as the tree matures.
Humidity
Average humidity of 40% to 60% suits it fine, so there's no number to chase outdoors. Indoor trees in dry winter air may appreciate a little extra moisture around the leaves.
Feeding
Feed monthly through spring and summer with a citrus fertilizer higher in nitrogen and carrying iron, zinc, and manganese. Stop the feeding in late season, since a late nitrogen push grows tender shoots that frost will burn.
Pruning
Prune in late winter to early spring to shape the tree and clear dead, crossing, or frost-damaged wood. Wear thick gloves: the branches carry long, sharp thorns that catch skin and clothing.
Repotting
Move container trees into a larger pot every 2 to 3 years, before the roots circle the inside or push out the drainage holes. Water running straight through without soaking in is another sign the tree has outgrown its pot.
Size & spacing
Yuzu matures at roughly 6 to 18 feet (1.8 to 5.5 m) tall and spreads 5 to 13 feet (1.5 to 4 m) wide, so give it open room. The size depends on rootstock and whether you grow it in the ground or hold it back in a pot.
When to plant
Yuzu follows the citrus calendar with a cold-hardy edge. It flowers in spring, ripens fragrant fruit through late autumn as the skin turns yellow, and goes in the ground after the last frost in zone 8 and warmer. Grafting is the usual way to start a new tree.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Seed late winter to early spring; yuzu is usually propagated by grafting rather than seed
- Plant: After the last frost in spring in zone 8 and warmer
- Harvest: Flowers in spring; aromatic fruit harvested in late autumn as it turns yellow
Hardiness
USDA hardiness zones: 8–11
Temperature: down to -12°C
Troubleshooting
Most yuzu trouble traces back to cold or to soil that's wrong for citrus. Read the early signs on the twigs and new leaves and you can step in before the tree sulks. Match what you see below, then act while it still helps.
Dead twig tips and dropped leaves after a cold winter
This is cold or frost damage, and it shows up most on young trees pushed past their hardiness limit. Scratch a suspect twig: brown, dry wood at the tip with green wood lower down confirms it. Wait for spring growth, then cut back to live wood, and shelter young trees with frost cloth through hard freezes.
Fix:
- Wait until new growth resumes in spring, then prune back to live wood
- Protect with frost cloth or move containers under cover during hard freezes
Yellow leaves with green veins on the newest growth
This pattern is interveinal chlorosis, a shortage of iron, zinc, or manganese that usually traces back to alkaline or waterlogged soil. The newest leaves turn yellow between their green veins while older leaves hold their color. Feed a citrus fertilizer with chelated micronutrients and fix the drainage so the roots can take the iron up.
Fix:
- Apply a citrus fertilizer containing chelated micronutrients
- Correct drainage and avoid overwatering
Toxicity
The fruit is the prize and is perfectly safe for people to eat, but the rest of the plant is another matter for animals. The peel, leaves, and stems hold essential oils and psoralens that give cats, dogs, horses, and other animals an upset stomach. Keep clippings and windfall peel out of reach of pets and livestock.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds
Safe for
People
Cats Mild
The essential oils and psoralens in the peel, leaves, and stems can leave a cat drooling, vomiting, or off its food, often with loose stools. Contact with the peel may also irritate the skin.
Dogs Mild
A dog that chews the leaves or peel usually shows an upset stomach, with vomiting, diarrhea, and a low, sluggish mood. The same oils can redden skin on contact.
Horses Mild
The peel, leaves, and stems carry the same citrus oils, so a horse that nibbles them may drool and develop diarrhea or general gut upset. The strong scent keeps most horses from eating much.
Rabbits Caution
The oily peel and foliage don't sit well in a rabbit's sensitive gut and can bring on soft stools or a loss of appetite. Keep trimmings out of the hutch rather than offering them as a treat.
Livestock Caution
Goats, sheep, and cattle may pick at fallen leaves or prunings, and a large mouthful of the oily material can loosen the stomach. The bitter taste usually limits how much they take.
Birds Caution
The essential oils in the peel and leaves can upset a bird's digestion, so keep pet birds away from clippings. A small taste of the flesh is far less of a worry than the peel.
People Fruit safe
The fruit, juice, and zest are prized in the kitchen and safe to eat, which is the whole point of growing the tree. Handling a lot of peel in sun can make sensitive skin react, so rinse your hands after juicing.
The branches also bear long, sharp thorns that can scratch curious pets and people.
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
Only a few named yuzu turn up outside Japan, and they split between fruit for the kitchen and fruit for show. These are the two worth knowing.
Yuzu Ichandrin
A widely grown seedling-type yuzu prized for extra cold hardiness and dependable fruiting in cooler climates.
Shishi Yuzu
Grown more as an ornamental novelty than for juice, it carries unusually large, bumpy fruit.
How to propagate
Yuzu is almost always grafted for speed and cold hardiness, though you can grow it from seed if you don't mind a long wait.
GraftingModerate
Late spring through summer when bark slips easily · 1 to 2 years before reliable fruiting
Grafting is the common commercial route, done from late spring through summer while the bark slips easily. Worked onto trifoliate rootstock, the tree gains cold hardiness and vigor and starts fruiting reliably within 1 to 2 years.
SeedEasy
Late winter to early spring, sown fresh · Several years to fruit
Sowing fresh seed in late winter or early spring is the easy way in, but patience is the price. Seedlings grow slowly and take several years to fruit, so seed is the simplest path rather than the fastest to a harvest.
Myths
Because the plant is toxic to pets, yuzu fruit is poisonous to people.
The pet warning is about essential oils and psoralens that upset cats and dogs, not the flesh on your plate. Yuzu zest, peel, and juice are everyday, safe ingredients in human cooking, from ponzu sauce to marmalade.
Yuzu is fully winter-proof and shrugs off any freeze.
It is one of the most cold-hardy true citrus and takes roughly 10°F to 15°F (-12°C to -9°C) once settled in. Young trees are another story, still needing frost protection and still prone to tip dieback after a hard freeze.