Plum

Site and soil

Plums want full sun and well-drained loam at pH 6.0 to 7.0. Like all stone fruit they will not tolerate standing water in the root zone, though European plums handle heavier ground better than Japanese types. Plant on a slope or raised site where water drains and cold air moves away from the bloom.

Japanese plums bloom earliest, often in March, which exposes them to late frost. Site them where bloom is delayed a few days, on a north or east slope, and give the European and hybrid plums, which bloom a little later, the warmer spots.

Spacing

Mature trees run 12 to 20 ft tall and wide. Set them 15 to 20 ft apart, or 12 to 15 ft if you keep them pruned small. Pollination partners of the same type should be within about 50 ft.

Planting

Plant in early spring while dormant, or in fall after leaf drop.

• Dig the hole as deep as the root system and two to three times as wide.
• Set the tree with the graft union 2 to 4 inches above the finished soil line.
• Backfill with native soil and water in well.
• Mulch 3 to 4 inches deep, kept back from the trunk.
• Paint or wrap the lower trunk white against winter sunscald, and guard it from rabbits, voles and deer.

Pollination

Match partners by type. European plums (Seneca, Mount Royal, Greengage) are partly self-fertile and pollinate each other, but crop much better with a second European variety. Japanese plums (Methley, Shiro, AU Producer, AU Rosa) need another Japanese plum; Methley is self-fertile and an excellent pollinizer for the rest. American hybrids (Toka, Waneta) need another hybrid or a Japanese plum, and Toka is a strong pollinizer for the group. European and Japanese plums bloom at different times and generally do not pollinate each other. The simplest plan is two Europeans plus Methley and Toka.

First-year care

• Water deeply once a week through the first growing season and in dry spells the second.
• Keep a grass-free mulched circle 3 to 4 ft across.
• Remove any fruit that sets in the first year.
• No fertilizer in year one, and lightly after that.

Pruning

Train Japanese and hybrid plums to an open center, since they grow wide and bear on spurs along the scaffolds. Train European plums to a central or modified leader, since they grow more upright. Do the structural work in the first three years.

Prune in late winter in dry weather, or right after harvest. Remove dead, crossing and inward wood and water sprouts, and keep the center open for light and air. Japanese plums grow fast and need more thinning of wood than Europeans.

Thin the fruit in late spring to one plum every 4 to 6 inches on Japanese types, which overset badly and break limbs. Watch for black knot, the hard black swellings on twigs: cut it out at least 4 inches below the gall in late winter and remove the prunings from the orchard. Brown rot on ripening fruit is reduced by thinning, air movement and picking up fallen fruit.

Harvest

Grafted plums begin bearing in about 3 to 5 years. Japanese plums ripen first, from late June into July, followed by the hybrids in August and the Europeans from August into September. A plum is ready when the skin has reached full color, the flesh gives slightly to a gentle press, and the fruit comes off with a light twist. European plums for drying can hang until they begin to shrivel at the stem.

Japanese plums are soft and keep only a few days; eat them fresh or cook them down. European plums keep a week or two refrigerated, dry well into prunes, and make the classic plum jam and butter. A mature tree gives 30 to 60 pounds. Birds and raccoons take their share as the fruit colors.