Tree · Rosaceae
Plum
Prunus domestica
Give it full sun, deep soil, and a yearly pruning, and a plum tree pays you back with baskets of fruit.
Full sun
Every 7–14 days
USDA 4–9
10–20 ft · 3–6 m
Overview
A plum tree earns its place in the yard. It belongs to the rose family alongside cherries, peaches, and apricots, and it splits into two main camps: the hardy European plums grown for prunes and cooking, and the juicier Japanese plums that ripen earlier and shine fresh off the branch. Both want a sunny spot and deep, well-drained soil, and both reward a grower who keeps up with the pruning.
Most of the work is choosing well at the start. Some European plums set fruit on their own, while most Japanese plums need a second compatible tree blooming at the same time to crop at all. Get the pollination right and a healthy tree comes into bearing in about 3 to 5 years, then carries fruit for decades.
The trade for that long life is steady care. Plums draw a handful of stubborn problems, from black knot in the wood to brown rot in the fruit, and a clean, open canopy is your best defense against all of them. Stay on top of the dropped fruit and dead wood, and the tree stays healthy and heavy with plums.
Care
The short version: full sun, deep and well-drained soil, and steady moisture while the fruit fills out. Prune every winter to keep the canopy open, feed lightly in early spring, and match the variety to a pollinizer if it needs one.
Light
Plums want full sun, ideally 6 or more hours a day, to ripen sweet fruit and dry the canopy after rain. They will take a little partial sun, but shade trades away both the crop and the open, airy growth that keeps disease down.
Water
Let the top half of the root zone dry between waterings, then water deeply. Young trees need regular drinks, while established ones shrug off some drought but size and set fruit far better with even moisture as the plums fill out. Steer clear of soggy ground, which invites root and crown rot.
Soil
Plant in deep, well-drained loam with plenty of organic matter worked in. A pH of 6.0 to 7.0 suits the tree, and the one thing to avoid is heavy, waterlogged soil that rots the roots and crown.
Temperature
Plums are cold-hardy trees that handle a range from about -29°F to 95°F (-34°C to 35°C). European types take hard winters in stride, but a late frost during bloom can still wipe out a season's fruit.
Humidity
Average outdoor humidity in the 40% to 70% range is fine, so there's no number to fuss over. What matters far more is airflow, since long damp spells in a crowded canopy are exactly what brown rot and black knot wait for.
Feeding
Feed once in early spring before new growth starts, using a balanced fertilizer or a simple nitrogen source. Go easy, because too much nitrogen pushes soft growth that fruits poorly and catches disease.
Pruning
Prune every year in late winter while the tree is dormant. Open Japanese types to a vase shape and train European types to a modified central leader, cutting out dead, diseased, and crossing wood, removing any black knot galls, and thinning the canopy so light and air reach the fruit.
Repotting
Plums are normally grown in the ground rather than in pots. Dwarf trees in large containers are the exception and need their soil refreshed or a move to a bigger container every 2 to 3 years.
Size & spacing
A standard plum reaches 10 to 20 feet (3 to 6 m) tall and spreads nearly as wide, so give it room. Plant trees far enough apart that the mature canopies don't crowd, which keeps air moving and disease in check.
When to plant
Plums run on the seasons. Set bare-root, grafted trees out in early spring while they are still dormant and the soil can be worked, watch them bloom in early to mid spring, and pick the fruit from late summer into early fall once it softens and colors up.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Early spring while dormant as bare-root, grafted trees, after the soil can be worked; container trees can go in from spring to early summer.
- Harvest: Blooms early to mid spring; European plums ripen late summer to early fall (about August to September), while Japanese plums often ripen somewhat earlier.
Hardiness
USDA hardiness zones: 4–9
Temperature: down to -34°C
Troubleshooting
Most plum trouble shows up in the wood, the blossoms, or the ripening fruit. Catch it early and you can often prune or clean your way out before it spreads through the tree. Match what you see below, then act while it still does some good.
Hard black galls swelling around twigs and branches
These knots are black knot, a fungus that infects new shoots in spring and builds woody galls that come back year after year. Cut each knot out in late winter, taking the branch a good 6 to 8 inches below the swelling, and burn or bin the prunings. Disinfect your saw between cuts and clear out any wild plums or cherries nearby, since they keep feeding the infection.
Fix:
- Prune out knots in late winter, cutting at least 6 to 8 inches below each gall, and destroy the prunings.
- Disinfect pruning tools between cuts and remove any infected wild plums or cherries nearby.
Browned blossoms and rotting fruit dusted with tan spores
This is brown rot, a fungus that hits hardest in warm, wet weather at bloom and again as the fruit ripens. It collapses the flowers, spreads soft rot through the fruit, and leaves shriveled mummies hanging on the tree. Strip off and destroy every rotted fruit and mummy, and in a wet year spray a labeled fungicide once at bloom and again as the plums color up.
Fix:
- Remove and destroy rotted fruit and mummies during the season and at cleanup.
- Apply a labeled fungicide at bloom and again as fruit ripens in wet seasons.
Crescent scars on young fruit that drops early
The telltale crescent scar is the work of the plum curculio, a small weevil that lays its eggs inside developing fruit. The grubs tunnel through, the fruit drops, and a cut-open windfall shows the C-shaped larva inside. Gather and destroy every dropped fruit to break the cycle, and spray a labeled insecticide at petal fall while the adults are out and active.
Fix:
- Collect and destroy dropped, infested fruit to interrupt the life cycle.
- Apply a labeled insecticide at petal fall and shuck split when adults are active.
Curled, sticky leaves with sooty mold
Curled, yellowing leaves coated in a sticky film point to aphids feeding on the tender new growth. They draw ants and leave behind honeydew that turns black with sooty mold. Knock light infestations off with a hard jet of water, or reach for insecticidal soap or horticultural oil, and let the lady beetles and lacewings do the rest before you spray anything stronger.
Fix:
- Wash light infestations off with a strong jet of water or use insecticidal soap or horticultural oil.
- Preserve natural enemies such as lady beetles and lacewings and treat only when populations are high.
Toxicity
The ripe flesh is good to eat, but the rest of the tree is not. Leaves, stems, bark, and the pits hold cyanogenic compounds that release cyanide when chewed or wilted, and wilted prunings are especially dangerous to grazing animals. Keep pets and livestock away from clippings and fallen pits, and never let anyone crack open a stone.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds
Safe for
People
Cats Toxic
A nibble of ripe flesh tends to cause nothing worse than mild stomach upset, but chewing leaves, twigs, or a cracked pit releases cyanide. Watch for drooling, bright red gums, and labored breathing, and treat any sign as an emergency.
Dogs Toxic
Dogs often crunch a fallen pit, and that is the real danger: the kernel and the wilting leaves give off cyanide, while the whole pit itself can lodge in the gut. Vomiting, panting, and weakness after chewing the tree warrant a fast call to the vet.
Horses Toxic
Horses are especially at risk, and wilted leaves blown into a paddock are the classic trap. The cyanide they carry can bring on brick-red gums, dilated pupils, staggering, and collapse within minutes, so keep prunings and fallen branches well out of reach.
Rabbits Toxic
Plum leaves, bark, and twigs are not safe browse for rabbits because the same cyanogenic compounds build up as the foliage wilts. Skip the prunings entirely and stick to rabbit-safe greens.
Livestock Toxic
Grazing animals such as cattle, goats, and sheep are most often poisoned by wilted leaves from a fallen or pruned branch, which concentrate cyanide as they dry. Sudden distress, gasping, and collapse can follow within an hour, so fence stock away from any plum prunings.
Birds Caution
Birds can eat the ripe flesh, and many fruit-eaters do so happily in the wild. The pits and leaves are the problem, since the cyanide inside is dangerous if a bird cracks and swallows the kernel, so offer only pitted flesh.
People Ripe fruit safe
Ripe plums are a wholesome fruit and safe to enjoy fresh or cooked. The catch is the pit, which holds cyanide and should never be cracked open or eaten, so spit it out and keep children from chewing it.
The hazard is the wilting leaves, twigs, and the pits (cyanide), not the ripe flesh. Keep pets and livestock away from prunings, wilted foliage, and fallen pits; pitted ripe plum flesh is a safe occasional treat in moderation.
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 plum cultivars exist, but a few turn up again and again in home orchards. These are the ones worth knowing by name.
Stanley
A widely grown, self-fruitful European prune plum that sets reliable blue freestone fruit good for drying, cooking, and eating fresh.
Damson
A small, tart, blue-black European plum prized mostly for jams, preserves, and cooking rather than fresh eating.
Santa Rosa
A popular Japanese plum with juicy reddish-purple fruit that is partly self-fruitful but crops best with a compatible pollinizer nearby.
Methley
An early, heat-tolerant Japanese plum that is self-fruitful and sweet, making it a good fit for warmer regions.
How to propagate
Plums are not started from seed the way an annual is. Named trees are joined onto rootstock, while seed is saved mostly for raising those rootstocks or breeding something new.
GraftingModerate
T-budding in late summer when bark slips, or whip grafting onto rootstock in late winter while dormant. · Bears fruit in roughly 3 to 5 years depending on rootstock and cultivar.
Named plums don't come true from seed, so growers bud or graft them onto plum rootstocks that set the tree's size, vigor, and tolerance of the soil. T-bud in late summer while the bark still slips, or whip graft onto dormant rootstock in late winter, and the young tree starts bearing in about 3 to 5 years depending on the rootstock and cultivar.
SeedModerate
Cold-moist stratify the cleaned pits over winter, then sow in spring. · Several years to fruit, and seedlings are not true to type.
Growing from a pit is mostly for raising rootstock or breeding new types, not for copying a named plum. Clean the pits, give them a cold, moist winter to break dormancy, and sow in spring, but expect several years to fruit and a seedling that won't match its parent.
Myths
Every plum tree needs a second tree to set any fruit.
It depends on the type. Many European plums like Stanley are self-fruitful and crop on their own, but most Japanese plums and a few European ones need a compatible cultivar blooming at the same time to fruit well, so check the variety before you plant a single tree.
Prunes come from a separate fruit unrelated to plums.
Prunes are simply dried plums. They come from certain freestone European plum cultivars that dry down without spoiling around the pit, which is why not every plum makes a good prune.
Plum pits are harmless to chew.
The pits, leaves, and stems hold cyanogenic compounds that release cyanide when crushed or chewed. A swallowed pit can also jam the gut, so spit it out and keep it away from pets and children.