How to Grow a Greengage
Plant Greengage in full sun on free-draining soil and give the tree 12 to 15 feet of clear space. Most Greengages are self-fertile but crop heavier with a second European plum nearby. Prune in mid summer to avoid silver leaf disease. First real harvests come in year 3 to 4.
Where to plant
Greengage is a small deciduous fruit tree hardy in USDA zones 5 through 9. A standard tree matures to about 12 to 15 feet tall and wide, and a tree on dwarfing rootstock stays closer to 8 to 10 feet. Pick the spot for the mature size now, since fruit trees resent being moved once established.
Sun
Six to eight hours of direct sun is the minimum for a good fruit set and the sugar that makes Greengage worth growing. Less than that produces sparse, tart fruit. A spot with morning sun and afternoon shelter from the strongest summer sun works well in the warmer end of the zone range.
Avoid frost pockets at the bottom of slopes. Greengage blooms early, and a late frost on open flowers wipes out the year's crop in one cold night.
Drainage
Greengage hates wet feet. Roots in soggy soil rot quickly, and a tree in heavy clay rarely lasts more than a few seasons. Dig a one-foot test hole and fill it with water. If it drains within a few hours, the spot is fine. If water sits overnight, build a raised mound 12 to 18 inches above grade and plant on top of it.
Soil
A loamy garden soil with plenty of organic matter is ideal. Work a few inches of compost into a wide area before planting. Greengage tolerates a fairly wide range of soil chemistry, but heavily acidic or chalky ground can show nutrient issues over time and benefits from an annual top dress of compost.
Space
A standard Greengage needs 15 feet of clear space in every direction, and a dwarf needs about 10. Most Greengages are partly self-fertile, but a second compatible European plum within 50 feet improves the crop noticeably. The pollinator should bloom at the same time, since varieties that flower early or late will not match up with the bloom window.
How to plant
Plant bare-root trees while dormant in late winter or very early spring, before bud break. Container-grown trees can go in any time during the growing season, though new roots establish fastest in cool weather. Soak bare-root stock for one to two hours in a bucket of water before planting.
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1Dig a wide shallow hole Twice as wide as the root spread but only as deep. Greengage roots run mostly sideways, so a wide hole helps them get established faster than a deep one.
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2Find the graft union Look for the swollen knee on the trunk where the rootstock meets the variety. This union must stay several inches above the finished soil line. Burying it lets the variety put down its own roots, which defeats the dwarfing rootstock and produces a giant tree.
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3Set the tree at the right depth Hold the tree so the graft is well above grade and spread the roots over a low cone of soil in the bottom of the hole. The first thick root flare should sit at or just above the surrounding ground.
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4Backfill with native soil Mix a couple of handfuls of compost into the dug-out soil and use that to fill the hole, firming it as you go. Skip the rich amendments and the fertilizer at planting. Roots get lazy in overly rich soil and never spread into the wider yard.
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5Water deeply and stake if needed Soak the entire root zone until the top foot of soil feels uniformly damp. A young tree on dwarfing rootstock benefits from a low stake for the first two seasons. Tie loosely with a soft strap so the trunk can still flex in the wind.
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6Mulch two to three inches deep Use wood chips or shredded bark, kept a few inches back from the trunk. Mulch keeps the root zone cool, holds moisture, and reduces grass competition during establishment.
Watering and feeding
Watering
Water deeply once a week through the first growing season to help the young tree establish. Soak the root zone rather than splashing the leaves. Drip irrigation or a soaker hose at the base works best and keeps the foliage dry, which reduces leaf disease.
After the first year, Greengage gets by on rainfall in most climates. Water deeply through extended summer dry spells, especially during fruit fill in early to mid summer. Uneven watering as the fruit sizes up causes splitting at the skin and pit cracking inside.
Feeding
Feed once in early spring as buds begin to swell, using a balanced fertilizer or one labeled for fruit trees. Heavy nitrogen produces lush leafy growth at the expense of fruit, so go light if the leaves are already a deep green.
An older bearing tree benefits from an annual top dress of compost out to the drip line each spring. Stop feeding by midsummer so the new wood can harden off before winter.
Pruning
Greengage and other European plums are pruned in mid summer rather than winter. Plums and cherries are vulnerable to silver leaf, a fungal disease that enters through fresh cuts in cool wet weather. Pruning between June and August, when the wounds dry quickly, almost eliminates the risk.
First three years: building the framework
Train the young tree to an open-center shape with three to four main scaffold branches starting about two and a half feet up the trunk. Each summer, cut back the central leader to that height and shorten the side branches by about a third to encourage strong wide-angled growth.
Remove anything growing straight up the center, anything crossing through the middle, and any low water sprouts at the base. The goal is a tree shaped like an open vase, with sunlight reaching every part of the canopy.
Annual summer pruning
From year four onward, prune lightly in midsummer each year. Cut out any dead, broken, or crossing wood. Shorten this season's new growth by about a third to encourage short fruiting spurs along the older branches. Take a few branches all the way out at the trunk to keep the canopy open to light and air.
Thinning the fruit
A heavy crop on a young Greengage breaks branches and produces small bland fruit. About four weeks after flowering, thin the developing fruit so the remaining ones are roughly two inches apart along the branch. The tree puts the same total energy into fewer larger fruit, the limbs handle the load, and the tree avoids the boom-and-bust cycle of one heavy year followed by nothing the next.
Harvest
Greengage is grown for the small round greenish-yellow fruit with honey-sweet amber flesh. A standard tree on dwarfing rootstock gives a serious first crop in year 3 to 4 and a heavy crop by year 5 to 6. Most harvests run from late July into early September depending on the zone.
When it is ready
A ripe Greengage looks dull rather than glossy, gives slightly to gentle pressure, and lifts off the branch with a small twist. The color shifts from a fresh grass green to a duller yellow-green, sometimes with a soft pinkish blush on the sunny side. Greengage is one of the rare plums that does keep ripening a bit off the tree, but flavor is always best on fruit picked dead ripe.
Taste a few from the sunny side of the tree first. They ripen unevenly across the canopy and pick over several rounds, not all at once.
Picking and storing
Twist gently rather than pulling. A ripe fruit detaches without tugging, and a fruit that resists needs another few days on the tree. Hold the picked fruit in a single layer in a shallow box, since stacking bruises the soft ripe flesh.
Ripe Greengage holds 3 to 5 days at room temperature and about a week in the fridge. The flavor is sweetest at room temperature, so bring cold fruit out an hour before eating. The harvest also cans, jams, and freezes well.
Common problems and pests
Most Greengage problems are weather and pest pressure on the fruit, with silver leaf disease as the one serious risk if pruning happens at the wrong time of year.
Fruit split open on the skin
Caused by uneven watering during fruit fill, when a long dry spell is followed by a heavy rain or deep watering. The skin cannot stretch fast enough to match the swelling flesh inside. Mulch two to three inches deep and water deeply through summer dry spells to keep soil moisture even.
No fruit set after a good flower show
Usually a late frost on open flowers, since Greengage blooms early. Cold rainy weather during bloom also keeps bees grounded. Plant in a spot sheltered from the worst spring frost pockets, and pair with a second compatible European plum within 50 feet to improve pollination.
Silver sheen on leaves and dying branches
Silver leaf disease, a fungal infection that enters through fresh pruning cuts in cool wet weather. Cut affected branches back to clean wood several inches below the silvery zone. Burn or bag the prunings. Prune only between June and August going forward, never in winter, to keep new cuts dry as they heal.
Brown rot on ripening fruit
Soft brown patches with fuzzy spore tufts on fruit close to harvest, especially in humid weather. Remove and discard every affected fruit and any mummified ones still hanging in the tree at the end of the season. A copper or sulfur spray during bloom and again as fruit colors up reduces infection in problem years.
Aphids on new growth
Small green or black insects clustered on shoot tips and the undersides of new leaves in spring. Knock them off with a strong spray of water. Heavy infestations respond to insecticidal soap. Avoid heavy nitrogen feeding, which produces the soft new growth aphids love.
Plum curculio damage
Crescent-shaped scars on young fruit, often with a worm tunnel through the flesh at harvest. The adult is a small grey-brown weevil that feeds on petals and lays eggs in tiny developing fruit. Lay a sheet under the tree at dawn and tap the branches, which knocks the dormant adults onto the sheet for disposal. A kaolin clay spray at petal fall and weekly for three weeks coats the fruit and deters egg laying.
Black knot on branches
Hard black warty growths girdling twigs and small branches, common across stone fruit and especially on plums. Cut every affected branch back to at least 6 inches into clean wood and burn the prunings. Inspect each winter and remove new knots before they sporulate in spring.
Yellowing leaves between green veins
Iron deficiency, common on alkaline soils. Apply a chelated iron product as a foliar spray for fast correction and renew acidic mulch like pine bark over the root zone. A soil test pinpoints whether the issue is true iron shortage or simply a soil chemistry problem that locks up iron the tree cannot use.
Branches breaking under a heavy crop
A young tree carrying too much fruit splits at the limb crotches and can lose a whole branch in one storm. Thin the crop in early summer so fruit are roughly two inches apart along each branch. Prop heavy fruiting limbs with a forked stick or a soft tie up to a higher branch through the final weeks of ripening.
Birds and wasps on ripe fruit
Both move in as the fruit sweetens. Bird netting draped over the tree two weeks before expected harvest handles most of the bird losses. Wasps target already-damaged fruit, so quick removal of cracked or pecked fruit keeps wasp pressure down without spraying.
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