Tree · Rutaceae
Lemon
Citrus limon
Give it full sun, deep but infrequent water, and protection from frost, and a lemon tree fruits for decades.
Full sun
Every 7–14 days
USDA 9–11
6–20 ft · 1.8–6 m
Overview
The lemon is a small evergreen tree in the citrus family, prized for its glossy leaves, fragrant white blossoms, and tart yellow fruit. It came from Asia by way of the Mediterranean and now grows wherever winters stay mild, in zones 9 to 11. Plant one in a warm, sunny spot and it carries flowers and fruit at the same time, sometimes all year round.
Lemons grow well in the ground in frost-free regions and just as happily in a large pot you can roll under cover when the cold arrives. A mature tree reaches 6 to 20 feet (1.8 to 6 m) tall, though dwarf types stay far smaller and suit a patio or sunroom. Almost every tree you buy is grafted onto a hardy rootstock, which is why a lemon grown from a pip rarely matches its parent.
Give a lemon what it wants and it asks for little in return. The big risks are frost, soggy roots, and a short list of citrus pests and diseases. Get the drainage and the watering rhythm right, watch the tender new growth, and the tree rewards you with fruit for many years.
Care
The short version: full sun and shelter from frost, deep watering only after the top few centimetres of soil dry out, well-drained soil rich in organic matter, and a monthly citrus feed through the growing season.
Light
Lemons crave full sun, ideally 8 hours or more a day, which is what drives heavy flowering and fruit. They'll take partial sun or bright indirect light indoors, but less light means a leggier tree and a thinner crop.
Water
Water deeply, then wait until the top few centimetres of soil dry out before watering again, usually every 7 to 14 days. Citrus hate both drought and soggy roots, so the rhythm matters more than the volume. A tree in a pot dries out faster and needs checking more often in the heat.
Soil
Plant in well-drained sandy loam with plenty of organic matter, and never let the roots sit in water. A slightly acidic pH of 5.5 to 6.5 keeps the tree taking up nutrients well. Drainage is the one thing a lemon will not forgive.
Temperature
Lemons are happiest in warmth and run from about 28°F to 100°F (-2°C to 38°C), though frost near that low end damages tender growth. Hold a potted tree above freezing through winter and it sails through.
Humidity
Average humidity of 30% to 60% suits a lemon fine, so there's no need to fuss over it. Indoors, the bigger concern is the dry air near a heater, where the odd misting or a pebble tray helps.
Feeding
Feed monthly through the growing season, spring into late summer, with a citrus-specific fertilizer higher in nitrogen. The added iron, zinc, and manganese head off the yellowing that citrus are prone to.
Pruning
Lemons need little shaping. Prune lightly in late winter or early spring to take out dead, crossing, or weak wood and any suckers below the graft union, and thin the canopy enough to let light and air through.
Repotting
Move a container tree into a pot one size larger every 2 to 3 years. Roots circling the pot, water running straight through, or growth that stalls despite feeding all tell you it's time to size up.
Size & spacing
A lemon tree grows 6 to 20 feet (1.8 to 6 m) tall with a spread of 5 to 15 feet (1.5 to 4.5 m), so give it open room or pick a dwarf for a tight spot or a container.
When to plant
A lemon runs on warmth and stops dead at frost. Set young trees out in spring once the cold has passed and the soil has warmed. Blossom comes mainly in spring, and the fruit takes its time, ripening roughly 6 to 9 months later with peaks that often land in winter.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: spring, after all danger of frost has passed and soil has warmed
- Harvest: Blooms mainly in spring but is everbearing in mild climates; fruit ripens roughly 6 to 9 months after bloom, with peaks often in winter. Trees are typically grafted onto rootstock rather than grown from seed.
Hardiness
USDA hardiness zones: 9–11
Temperature: down to -7°C
Troubleshooting
Most lemon trouble lands on the leaves first, whether it's a pest mining the new flush or a fungus blistering the older foliage. Learn to read those early signs and you can act before the tree slips. Match what you see below, then deal with it while it still helps.
Blotchy mottled leaves, dieback, and lopsided bitter fruit
These are the marks of Huanglongbing, or citrus greening, a bacterial disease carried by the Asian citrus psyllid that slowly kills the tree. There is no cure, so a confirmed tree has to come out to protect the trees around it. The blotchy mottling crosses the veins unevenly, which sets it apart from a tidy nutrient deficiency, and any suspected case should go to your agricultural agency for testing.
Fix:
- There is no cure; remove and dispose of confirmed infected trees to protect the area
- Report suspected cases to your state department of agriculture or extension office
- Manage the Asian citrus psyllid vector
Sticky leaves, black mold, and bumps along the stems
Those small fixed bumps are scale insects drinking sap, and the sticky film and black mold are the honeydew they leave behind. Wipe or prune off a light run, then coat the rest with a narrow-range horticultural oil for full cover. Knock back any ants too, because they farm the scale and chase off the predators that would otherwise clean it up.
Fix:
- Wipe or prune off light infestations
- Apply horticultural or narrow-range oil for thorough coverage
- Control ants to allow natural predators and parasitoids to work
Greasy yellow-brown blisters under the leaves
This is greasy spot, a fungus that blisters the undersides of older leaves after warm, humid spells and eventually drops them. Rake up and bin the fallen leaves where the spores overwinter, and open the canopy with a little pruning so the foliage dries faster. A copper or oil spray timed to the summer flush helps where it's recommended for your area.
Fix:
- Rake and remove fallen leaves that harbor spores
- Improve airflow through pruning
- Apply a copper or horticultural oil spray timed to summer leaf flush where recommended
Silvery winding trails and curled new leaves
This is the work of the citrus leafminer, whose larvae tunnel inside the soft new flush. Pinch off the worst-hit growth and go easy on nitrogen and light pruning, since both push out the tender leaves the pest favors. On an established tree the damage looks alarming but rarely costs you fruit, so a light touch beats reaching for a spray.
Fix:
- Prune off and dispose of heavily mined new flush
- Avoid excess nitrogen and frequent light pruning that forces vulnerable new flush
- Use horticultural oil on new growth; protect natural parasitoid wasps by avoiding broad-spectrum insecticides
Toxicity
The flesh and juice are safe for people, but the rest of the tree is not pet-friendly. The peel, leaves, and seeds hold essential oils and psoralens that the ASPCA flags as toxic to cats and dogs, and the same compounds can upset other animals. Keep rinds, prunings, and any concentrated citrus oils away from pets.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds
Safe for
People
Cats Mild
A cat that chews the peel or leaves usually shows vomiting, loose stools, drooling, and a flat, depressed mood. Concentrated citrus oil on the skin can also leave it sensitive to sunlight.
Dogs Mild
Expect an upset stomach, diarrhea, and low energy if a dog gnaws on bark, leaves, or peel. Strong citrus oils can make the skin react in sunlight, so keep those products off your dog.
Horses Mild
The same oils and psoralens in the peel and leaves can unsettle a horse's gut and leave it dull. Most horses turn their nose up at the bitter foliage, so trouble is uncommon.
Rabbits Caution
The fragrant oils in the peel and leaves don't suit a rabbit's sensitive digestion. Skip the rind and greenery, and treat even a little juicy flesh as an occasional nibble at most.
Livestock Caution
Cattle, goats, and sheep rarely browse citrus, but the oily peel and leaves can irritate the stomach if they do. Keep prunings and windfall fruit out of grazing areas to be safe.
Birds Caution
The concentrated oils in the rind and leaves are best kept away from pet birds, whose systems handle such compounds poorly. A small taste of the plain flesh is the most they should ever have.
People Flesh safe
The flesh and juice are everyday kitchen staples and safe to eat and drink. Handling a lot of peel or oil can leave skin sensitive to sunlight, so rinse your hands before heading out into the sun.
Keep peels, leaves, seeds, and any concentrated lemon essential oils away from pets, and avoid applying citrus oil products to animals.
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
Hundreds of lemon selections exist, but a few show up in nearly every garden and grocery aisle. These are the ones worth knowing by name.
Eureka
The familiar grocery-store lemon, nearly thornless and everbearing year-round in mild climates.
Lisbon
A vigorous, thorny tree that crops heavily in seasonal flushes and shrugs off both cold and heat better than Eureka.
Meyer
A lemon-mandarin cross with sweeter, less sour fruit and a thin orange-tinged rind that makes a favorite dwarf container tree.
How to propagate
Lemons are nearly always multiplied by grafting, but you can also strike a cutting or sow a seed if you accept the trade-offs each route brings.
GraftingDemanding
Active growing season, late spring to summer · A season or more for the graft to take and push growth
Grafting is the standard commercial route, where a chosen lemon scion is budded onto a vigorous, disease-resistant rootstock during the active growing season from late spring into summer. It takes skill, and the graft needs a season or more to knit together and start pushing growth, but the payoff is a tree that fruits true with the toughness of the rootstock.
Stem cuttingsModerate
Spring to early summer from semi-hardwood growth · Several weeks to a few months to root
You can root a lemon from semi-hardwood cuttings taken in spring or early summer, and they strike in anywhere from several weeks to a few months. The resulting tree grows on its own roots, which is simpler than grafting, but it gives up the disease resistance and vigor that a good rootstock would have brought.
SeedModerate
Sow fresh seed from ripe fruit · Many years to reach fruiting size, if ever true to type
Sowing fresh seed from ripe fruit is easy enough, but the seedlings come up variable, often thorny, and take many years to reach fruiting size, if they ever fruit true to the parent. For that reason seed is used mostly for breeding work and raising rootstock rather than for growing a tree you mean to harvest.
Myths
Lemon trees grow true to type from supermarket seeds.
Shop lemons are grafted onto a separate rootstock for disease resistance and reliable fruit, so a seedling won't copy its parent. What you get instead is a slow, variable, often thorny tree that may never fruit the way you hoped.
Lemon plants and their oils are harmless around cats and dogs.
The ASPCA lists Citrus limon as toxic to cats and dogs, thanks to the limonene, linalool, and psoralens packed into the peel, leaves, and seeds. Keep the rind, foliage, and any concentrated citrus oils well out of a pet's reach.