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How to Grow Plums: Rootstock, Pollination and Pruning

Plums crop within three to five years if you get the rootstock, pollination group and pruning season right — prune in summer, never winter.

By Zakaria 3 min read Save to Pinterest — opens Pinterest in a new tab
A cluster of ripe purple plums hanging from a branch against blue sky
Photo: Couleur, Pixabay Content License, via Pixabay
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Plums are straightforward with three decisions made correctly: rootstock, pollination group, and pruning in summer rather than winter.

Planting

  1. Full sun, sheltered from wind and late frost. Plums flower early
  2. Well-drained soil, pH 6.0–7.0. They dislike waterlogging
  3. Plant bare-root in late autumn to early spring, container-grown any time the ground is workable
  4. Same depth as it grew — the graft union stays well clear of the soil
  5. Stake a dwarf tree permanently, a larger one for the first two years
  6. Mulch a wide ring, kept clear of the trunk
  7. Water weekly through the first two or three summers

Rootstocks

rootstockmature heightnotes
Pixy8–10 ftSmall gardens; needs good soil and water
St Julien A12–15 ftThe standard garden choice
Myrobalan B20 ft+Full standard; vigorous
Marianna 262412–18 ftCommon in the US

Pollination

self-fertileneeds a partner
VictoriaCoe’s Golden Drop
OpalJefferson
CzarMost gages
StanleyKirke’s Blue
Marjorie’s SeedlingEarly Laxton

A partner must flower in the same period and sit within roughly fifty feet.

Winter pruning is how plum trees die

Silver leaf and bacterial canker infect through wounds in cool damp weather. Prune young trees in spring as growth starts and established trees lightly in mid-summer after fruiting. Make clean cuts and leave them unsealed.

Pruning by age

  • Years 1–3: build an open framework of four or five main branches in spring. Remove anything crossing or heading into the centre
  • Established: a light mid-summer tidy — dead, damaged, crossing and crowded wood only. Plums fruit on both old and young wood, so heavy pruning is unnecessary
  • Never take out more than about a fifth of the canopy in a year

Thinning and support

  • Thin to 2–3 inches apart after the natural June drop
  • Support heavy branches with props before they bend, not after
  • A full unthinned crop breaks limbs, and the break invites silver leaf

Why it might not fruit

causefix
No pollination partnerPlant a compatible variety, or a family tree
Frost at blossomSite out of frost pockets; fleece a small tree
Winter pruning damageSwitch to summer pruning
Too much nitrogenStop feeding; use potassium instead
Too youngWait — 6 years on a vigorous rootstock
Biennial bearingThin the heavy crop to even it out

Common questions

When should a plum tree be pruned?

In late spring or summer, while the tree is in active growth, and never in winter. Plums and all stone fruit are vulnerable to silver leaf and bacterial canker, both of which infect through pruning wounds in cool wet conditions; a tree pruned in summer seals its wounds quickly. Prune young trees in spring to build the framework and established trees lightly in mid-summer after fruiting. If you only remember one thing about plums, it is this.

Do plum trees need a pollination partner?

Many do, and several popular varieties do not. Victoria, Opal, Czar and Stanley are self-fertile and will crop alone; Coe's Golden Drop, Jefferson and most gages need a compatible partner flowering at the same time within about fifty feet. Pollination groups are published for every named variety and are worth checking before buying — a plum that never fruits despite flowering well is usually a pollination problem rather than anything you did.

What rootstock should I choose for a plum?

Pixy for a small tree of about eight to ten feet, St Julien A for a bush or half-standard at twelve to fifteen feet, and Myrobalan for a full standard at twenty feet or more. St Julien A is the usual garden choice and suits most soils; Pixy needs good soil and consistent watering. In the US, Marianna 2624 and Krymsk rootstocks fill similar roles. As with pears, the rootstock sets the mature size and the variety barely affects it.

Why is my plum tree not fruiting?

Five usual reasons. No pollination partner for a variety that needs one; frost killing the blossom, since plums flower early and a single cold night at full bloom removes the crop; winter pruning causing dieback and stress; too much nitrogen producing leaves instead of flower buds; or simply age, as a tree on a vigorous rootstock may take six years or more. Biennial bearing is also common — a heavy crop one year exhausts the tree for the next unless you thin.

Should plums be thinned?

Yes, and most gardeners do not. Thin the fruitlets to about two to three inches apart once the natural June drop has finished, which sounds brutal and produces larger better fruit, prevents branches breaking under weight, and reduces the biennial cropping cycle. An unthinned plum tree carrying a full crop regularly snaps limbs, and the broken wound is then an entry point for silver leaf. Support heavily laden branches as well as thinning.

How long until a plum tree fruits?

Three to five years on a dwarfing rootstock such as Pixy, four to six on St Julien A, and six or more on a vigorous standard. Expect a small crop first and a proper one a year or two later. Remove the fruit entirely in the first year after planting so the tree puts its energy into roots and framework — it is the least satisfying piece of fruit-growing advice and one of the most worthwhile.

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