Tree · Meliaceae
Neem Tree
Azadirachta indica
Give it heat, sun, and free-draining soil, and the neem tree shrugs off drought and poor ground for decades.
Full sun
Every 7–21 days
USDA 10–12
50–75 ft · 15.2–22.9 m
Overview
The neem is a fast-growing evergreen of the mahogany family, native to south Asia and now planted across the warm parts of Asia and Africa. Left to its own devices it climbs to a broad, shady tree, and it does it quickly. People have leaned on neem for generations, from chewing the twigs to pressing the seeds for oil.
What sets neem apart in the garden is its seed oil. The seeds are rich in azadirachtin, a compound that puts insects off their food and throws their growth and breeding out of step, which is why gardeners turn neem into a natural pesticide. The leaves carry a long medicinal tradition of their own and are far gentler than the concentrated oil.
It asks little once it's settled. Neem takes heat to 113°F (45°C), shrugs off drought, and grows in poor, rocky, even mildly salty ground. Its one true limit is cold, since frost cuts it back and a hard freeze can kill it, so it stays outdoors only in the warmest zones.
Care
The short version: full sun and warmth, deep well-drained soil, and a deep soak for young trees during dry spells while you let the surface dry between waterings. Once established it handles drought and poor ground on its own, but it cannot take frost.
Light
Neem wants full sun and grows fastest in the open, though it puts up with partial sun or light shade. The more direct light it gets, the denser and stronger the crown.
Water
Water young trees deeply during dry spells, then let the top half of the soil dry before the next drink, roughly every 7 to 21 days. Once a neem is established it handles real drought, and the one thing it won't forgive is waterlogged ground.
Soil
Plant in deep, well-drained sandy or loamy soil. Neem isn't fussy and tolerates poor, rocky, and mildly salty ground, working across a wide pH band of 6.0 to 8.0. What matters most is drainage, since the roots rot in soil that stays wet.
Temperature
This is a tropical to subtropical tree, comfortable in heat all the way to 113°F (45°C). The hard limit is at the cold end, around 41°F (5°C), below which frost scorches the leaves and a freeze can kill a young tree.
Humidity
Average humidity suits it, somewhere in the 40% to 70% range, and it tolerates the dry air of semiarid regions well. There's no need to mist or fuss over moisture in the air.
Feeding
Feed through spring and summer with a balanced slow-release fertilizer or compost, once a season is plenty. Neem grows well in lean soil, so heavy feeding does more for pests than for the tree by pushing out soft, sappy growth.
Pruning
Prune in late winter to early spring to shape the crown and take out any dead, damaged, or crossing branches. Neem takes hard pruning and even pollarding in stride, which makes it a good candidate for a clipped hedge.
Repotting
A container-grown neem needs repotting every 2 to 3 years while it's young, before the roots circle and choke the pot. In a frost-free climate, the better long-term move is to plant it straight into the ground.
Size & spacing
A mature neem is a big tree, reaching 50 to 75 feet (15 to 23 m) tall with a broad canopy that can spread 40 to 60 feet (12 to 18 m) across. Give it plenty of open room and keep it well clear of buildings, paving, and smaller plantings.
When to plant
Neem runs on warmth and won't survive frost. Sow fresh seed in late winter or early spring under cover, set young trees out in spring once the soil has warmed and the cold has passed, and look for fragrant white flowers in spring followed by olive-like drupes from summer into early fall.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Late winter to early spring in frost-free warmth; sow fresh seed because viability is short
- Plant: Spring after all danger of frost, once soil is warm
- Harvest: White fragrant flowers in spring; olive-like drupes ripen summer to early fall
Hardiness
USDA hardiness zones: 10–12
Temperature: down to -1°C
Troubleshooting
A neem in the right climate gives little trouble, so most problems trace back to cold, soggy soil, or sap-sucking pests. Read the early signs on the leaves and roots and you can step in before any of it spreads. Match what you see below, then act while it still helps.
Wilting and yellowing with soft, dark roots
When a neem in soggy ground wilts and yellows, suspect root rot. Dig down and you'll find brown, mushy roots instead of firm pale ones. There's no real cure once it sets in, so stop overwatering, fix the drainage, and replant in deep, sandy soil where the surface can dry between waterings.
Fix:
- Improve drainage and stop overwatering
- Remove affected plant material
- Replant in deep, sandy, well-drained soil
Scorched leaves and dieback after a cold snap
Neem is a tropical tree with no tolerance for frost, and the damage shows up on the exposed outer foliage once temperatures drop below about 41°F (5°C). It is hardy only in zones 10 to 12. Cut out the dead wood after the danger of frost has passed, and keep young trees under cover or in a pot you can move indoors when the cold comes.
Fix:
- Prune out dead wood after the danger of frost has passed
- Protect young trees with frost cloth or grow in containers that can be moved indoors
- Site in a warm, sheltered location
Black sooty film and a sticky coating on the leaves
The black layer is sooty mold, and it grows on the sugary honeydew dropped by scale, whitefly, or aphids feeding above it. Check the shoot tips and leaf undersides for the insects, since the mold itself is harmless and wipes right off. Rinse the foliage, treat the pests with horticultural soap or oil, and let natural predators do the rest.
Fix:
- Rinse foliage and wipe off mold
- Control the sap-sucking insects with horticultural soap or oil
- Encourage natural predators
Toxicity
The leaves are low in toxicity and have a long history of medicinal use, so a curious nibble is rarely cause for alarm. The real caution is the concentrated neem oil and the seeds, which are rich in azadirachtin and can sicken pets and people if swallowed in quantity. Cats are the most sensitive, so keep the oil and seed products stored well out of reach.
Toxic to
Cats · Dogs · People
Safe for
Horses · Rabbits · Livestock · Birds
Cats Mild
The leaves are low in toxicity, but cats are the most sensitive to concentrated neem oil. Drooling, vomiting, and lethargy can follow if a cat ingests or is treated with the undiluted oil, and reported cases include tremors, twitching, and convulsions. Keep the seed oil and extracts well out of reach.
Dogs Mild
A nibbled leaf rarely amounts to much. The risk is the concentrated oil, which can bring on vomiting, drooling, and a dull, sluggish dog if it's swallowed or laid on too thick. Dogs handle diluted topical neem better than cats do.
People Caution
Neem leaves have a long history of medicinal use and are low-toxicity, but the concentrated oil and the seeds are a different matter. Swallowing them in quantity can cause vomiting and worse, and that risk is highest for small children, so keep neem oil and seed products stored safely.
Horses Safe
The foliage poses little hazard to a grazing horse. Store the concentrated neem oil and seed products where a horse can't get into them.
Rabbits Safe
Browsed leaves are low-toxicity for rabbits. Trouble would only come from the concentrated oil or a quantity of crushed seed, neither of which a rabbit should reach.
Livestock Safe
Cattle, goats, and sheep can browse neem foliage with little risk, and the leaves are even used as fodder in parts of its range. The caution is the seed oil, which shouldn't be fed.
Birds Safe
Neem holds no particular danger for birds at the leaf or fruit. Keep them away from any concentrated oil or extract.
Keep concentrated neem oil and neem seed products away from pets; never apply undiluted neem oil to a cat or dog or allow them to ingest it.
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
Neem is grown in two main forms, one bred for the kitchen and one for its potent seed oil. These are the ones worth knowing apart.
Azadirachta indica var. siamensis (Thai neem)
This Southeast Asian form carries young leaves and flowers mild enough to eat as a vegetable, where the common type is far too bitter.
Common neem (typical var. indica)
The widely grown South Asian type is prized for its azadirachtin-rich seed oil, which gardeners press into a botanical biopesticide.
Companions
Neem earns its keep near vegetable and fruit crops, where its leaf and seed extracts deter many garden pests, but its dense shade, hungry roots, and allelopathic leaves make poor company for small plants growing right beneath it.
Plant near
Vegetable and fruit crops: Neem leaf and seed extracts are used as a botanical biopesticide that deters many garden pests.
Keep apart
Shallow-rooted understory plants: Its dense shade, vigorous roots and allelopathic leaf compounds suppress small plants growing directly beneath it.
How to propagate
Neem is easy to multiply, almost always from seed, with cuttings held in reserve for when fresh seed isn't around or you want a copy of a particular tree.
SeedEasy
Sow fresh seed in spring in warm conditions · Germinates in 1 to 3 weeks; transplant after a few months
Most neem trees are grown from seed, and the catch is timing. The seed loses its viability fast, so sow it soon after the fruit ripens, in spring warmth. It sprouts in 1 to 3 weeks and is ready to transplant after a few months.
Stem cuttingsModerate
Warm season from semi-hardwood cuttings · Roots in several weeks under warmth and humidity
Take semi-hardwood cuttings in the warm season when no fresh seed is on hand, or when you want a copy of a particular tree. Kept warm and humid, they root over several weeks.
Myths
Neem oil is natural, so it is completely safe for every pet.
Its active compound azadirachtin can cause drooling, vomiting, and tremors, and concentrated neem oil has sickened and in some reported cases killed cats. Use only heavily diluted oil and keep the concentrate away from animals.
Neem instantly kills any insect it touches.
Neem mostly deters feeding and disrupts the way insects grow and breed, so it works over days, not seconds. It thins a pest population gradually rather than knocking everything down on contact.