Tree · Juglandaceae
Pecan
Carya illinoinensis
Give it room, full sun, and a pollination partner, and a pecan shades the yard for generations.
Full sun
Every 7–14 days
USDA 6–9
66–131 ft · 20–40 m
Overview
A pecan is a long-lived shade tree that also drops a nut crop from its high branches. It belongs to the walnut family and grows wild in the river valleys of the south-central United States, throwing up a broad, towering canopy of long, feather-cut leaves. Each leaf splits into paired leaflets along a central stalk, and a healthy tree carries that foliage for a hundred years or more.
The sheer bulk of the trunk and crown sets the planting distance. A mature pecan lifts to 66 to 131 feet (20 to 40 m) tall on a heavy, straight bole, spreading a crown just as wide, so it needs open ground well back from houses, walks, and power lines. The wood is brittle for all its size, and whole limbs crack and fall in ice and wind.
The nuts hang in husked clusters and take patience to fill. Pecans are wind-pollinated, dangling slender green catkins that shed pollen onto tiny flowers whose timing is staggered, so a lone tree sets poorly and two compatible cultivars fill far more shells. Add the tree's steady pull on zinc and the long years before the first nuts drop, and the pecan is a tree that rewards a patient eye.
Care
The short version: full sun and deep, well-drained soil, with room for a broad, heavy-limbed tree. Water deeply but not often, feed with nitrogen and zinc through the growing season, and plant a second cultivar nearby for pollination.
Light
A pecan needs full sun to fill its nuts, ideally 8 or more hours a day striking the whole crown. A young tree tolerates a little partial sun, but heavy shade thins the feathery foliage and leaves few nuts to swell.
Water
Water deeply but not often, letting the top half of the root zone dry between soakings so the deep roots reach down. Young trees need regular deep watering to settle in, and even a mature tree wants a long soak while the kernels are filling and through late-summer drought. Shallow, frequent sprinkling only wets the surface and does more harm than good.
Soil
Give a pecan deep, fertile, well-drained sandy loam to loam for its wide-ranging roots. It rides out the odd flood but rots in standing water, and it likes a pH between 6.0 and 7.0, which keeps zinc loose enough for the roots to take up.
Temperature
Pecans stand a wide swing, from about -4°F to 104°F (-20°C to 40°C), and the hot end matches the long summers that ripen the kernels. The deep cold tolerance holds once the bare, dormant tree has hardened for winter.
Humidity
The trees grow across 40% to 70% humidity, so no reading is worth chasing outdoors. Warm, damp air does settle scab onto the leaves and shucks, which puts the weight on airflow and resistant cultivars rather than the number.
Feeding
Feed from early spring through early summer with a balanced nitrogen fertilizer, then work zinc in by soil or foliar spray. A zinc shortage is common and shows first in small, crinkled, rosetted new leaves, so it belongs in the regular routine.
Pruning
Prune in late winter while the branches are bare and dormant. Train a young tree to a single upright central leader and cut away crossing, dead, or weak limbs; a mature tree needs little beyond clearing its brittle deadwood.
Repotting
Field-grown pecans are never repotted, and a long, deep taproot makes them hard to lift, so the site is chosen with care. Move young nursery stock just once while dormant, and read circling roots, stalled top growth, or fast-drying soil as a container tree outgrowing its pot.
Size & spacing
Plan for a heavy, wide-crowned giant. A pecan rises to 66 to 131 feet (20 to 40 m) tall with a spread of 39 to 75 feet (12 to 23 m), so set it well back from buildings and lines and clear of other trees.
When to plant
A pecan is set out while its branches are still bare. Plant young dormant trees in late winter to early spring once the hardest freezes have passed, and the slender catkins unfurl in spring. The husked nuts ripen late, splitting and dropping from October into November.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: late winter to early spring while dormant, after the worst freezes
- Harvest: wind-pollinated catkins and flowers in spring; nuts ripen and are harvested October through November
Hardiness
USDA hardiness zones: 6–9
Temperature: down to -23°C
Troubleshooting
Most pecan trouble writes itself onto the leaves and the developing nuts: a wet-weather fungus, a shortage that warps the new growth, or insects clustered on the leaf undersides. Read those close-up signs early and there is time to step in before a season's crop is lost. Match what the foliage and shucks show below, then act while it still helps.
Olive-black sunken lesions on the leaves and shucks as nuts fall
Those olive-black, sunken pits pressed into the leaves and the green shucks are pecan scab, a fungus that swells in warm, humid air and ruins more crops than anything else across the wet Southeast. A protective fungicide schedule held through the season shields the surfaces before the spots take hold. Wider spacing and pruning let air slide through the canopy, and scab-resistant cultivars carry the crop where the summer stays damp.
Fix:
- Apply recommended fungicides on a protective schedule during the growing season
- Improve air movement by proper spacing and pruning
- Plant scab-resistant cultivars in humid regions
Small, crinkled, yellow-mottled leaves knotted into tight rosettes
New leaflets that emerge small, crinkled, and mottled yellow, packed into tight tip rosettes on stubby stems, mark a zinc shortage that pecans meet on sandy or high-pH soils. A foliar zinc spray wetting the fresh spring growth feeds the deficiency straight through the leaf surface. A soil correction guided by a test, and a pH held near 6 to 6.5, lets the roots draw zinc up so later leaves unfurl broad and flat.
Fix:
- Apply foliar zinc sprays to new growth in spring
- Correct soil zinc per soil test recommendations
Glossy sticky leaves, a black sooty film, and early leaf drop
Leaves that turn glossy and tacky under a spreading black film point to pecan aphids clustered along the leaf undersides, raining honeydew that sooty mold soon blackens. Lady beetles and lacewings pick the colonies off in most seasons, so a targeted insecticide waits for the surge that threatens to strip the foliage. A lighter hand with nitrogen holds back the soft, pale new growth the aphids crowd onto.
Fix:
- Encourage natural predators such as lady beetles and lacewings
- Use targeted insecticides only when populations are damaging
Toxicity
The ripe, oily kernel inside a pecan shell is a safe, well-loved food for people, and the tree itself carries fairly little risk. The catch lies in moldy fallen nuts, which can hold tremor-causing mycotoxins, and in the heavy oil of a whole nut that upsets a pet's stomach. Rake up the split, husked drops and keep pets from scavenging, and the worry mostly clears.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds
Safe for
People
Cats Mild
A cat that gnaws a fallen nut can end up with a stomach unsettled by the rich, oily kernel. The sharper worry is a moldy nut, whose mycotoxins can set off tremors or worse.
Dogs Mild
Dogs nose out fallen nuts more than any other pet, and the oily kernel often brings on vomiting or loose stool. Trembling or an unsteady gait marks a moldy nut and warrants a vet.
Horses Mild
Fresh nuts and the pinnate leaves seldom trouble a horse, yet moldy fallen nuts worked into feed or pasture carry the same tremor-inducing mycotoxins. Clearing the ground beneath a grazed tree removes them.
Rabbits Mild
A rabbit's gut is tuned to fibrous greens, not oily kernels, so even a fresh nut can unsettle it. Pecans make a poor treat, and fallen, moldy nuts stay out of reach.
Livestock Mild
Cattle, goats, and sheep grazing under the spreading canopy can take up moldy windfall nuts, where the mold toxins rather than the tree pose the hazard. Cleared drops break the path.
Birds Mild
Backyard hens peck at split, cracked nuts on the ground without harm, though moldy ones carry the same mycotoxin risk. Raking the drops keeps anything rotten out of the pecking.
People Safe
The ripe, buttery kernel inside the shell is a well-loved and safe food. Only nuts gone moldy on the ground are the exception, and those stay away from pets.
Keep fallen nuts raked up so pets cannot scavenge moldy ones; the fresh kernels are not considered highly toxic but the high fat content and obstruction risk make them unsuitable as pet treats.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
United Kingdom
Animal PoisonLine: 01202 509000 (fee applies)
Australia
Animal Poisons Helpline: 1300 869 738
Varieties
Pecan cultivars are told apart by when their catkins release pollen and how well their leaves and shucks shrug off scab. These are the names met most often, and pairing two of them is what fills the shells.
Pawnee
A Type I cultivar whose nuts fill and ripen early, which fits it to the northern edge of pecan country.
Desirable
A Type II cultivar that swells large, plump, high-grade kernels, though its shucks scab badly in humid regions.
Elliott
A Type II cultivar planted through the humid Southeast because its foliage and shucks resist scab so well.
Stuart
An old, widely planted Type II cultivar that crops steadily and keeps its shucks fairly clear of scab.
Companions
Plant near
Crimson clover or other legume cover crops: Cover crops between rows add nitrogen, reduce erosion, and support beneficial insects in orchards.
Keep apart
Tomato: Pecan produces juglone (milder than black walnut), which can stress juglone-sensitive plants like tomato grown directly beneath the canopy.
How to propagate
A named pecan will not grow true from its own nut. Cultivars are grafted onto seedling rootstock, joining scion to stock, while seed is grown mainly to raise that rootstock.
GraftingDemanding
Late winter to spring for whip and tongue or patch budding in summer · Named cultivars graft onto seedling rootstock and begin bearing in roughly 4 to 8 years
A named pecan will not come true from its own nut, so growers splice or bud it onto a vigorous seedling rootstock, matching the cut faces of scion and stock. The whip and tongue graft is joined from late winter into spring and the patch bud set in summer, and the fused tree bears its first nuts in roughly 4 to 8 years.
SeedModerate
Stratify nuts over winter and sow in spring · Seedlings used mainly as rootstock; seedling-grown trees are variable and bear after many years
A sown nut grows a rootstock seedling rather than a true copy of a named cultivar. The nut chills through winter to break dormancy and pushes up in spring, but the seedling that rises is variable in leaf and nut and waits many years to bear.
Myths
A single pecan tree will reliably crop on its own.
A lone pecan sets few nuts. It is wind-pollinated and staggers its bloom, so a Type I tree sheds its dangling pollen catkins before its own small flowers turn receptive, and a Type II tree reverses that order. Plant both types near each other and the drifting pollen lifts the harvest far past a single solitary tree.
All pecans are dangerously poisonous to dogs.
The kernel itself is not highly toxic, though a whole nut in its hard shell can upset a stomach or lodge as a blockage and packs heavy oil. The real danger is moldy nuts, which can hold tremor-causing mycotoxins, so raking up the drops answers the risk rather than fearing the tree.