Plums sold in North American nurseries fall into two main categories: European plums (Prunus domestica) and Japanese plums (P. salicina). They differ in fruit type, bloom time, pollination requirements, cold hardiness, and to some extent the diseases they attract. Understanding which type you're growing is essential because they have different management requirements.
I don't grow plums at my zone 7a Long Island plot. Both types would grow here, with some disease management required. This guide is sourced from Penn State, Cornell, and Oregon State Extension.
European vs Japanese plums at a glance
Per Penn State Extension:
| Characteristic | European plum (P. domestica) | Japanese plum (P. salicina) |
|---|---|---|
| Fruit | Oval, purple/blue/green; freestone | Round, red/yellow; clingstone or semi-free |
| Flesh texture | Dense, less juicy | Juicier, softer |
| Use | Fresh, prunes, jam | Primarily fresh eating |
| Self-fruitful | Many are | Mostly require pollinators |
| Cold hardiness | Zones 4-7 | Zones 5-9 |
| Bloom time | Later (less frost risk) | Earlier (more frost risk) |
| Brown rot susceptibility | Moderate | Higher |
USDA hardiness zones
Per Penn State Extension:
- European plum: USDA zones 4-7 optimal; some varieties to zone 3
- Japanese plum: USDA zones 5-9; early bloom makes late-frost damage a significant risk in zones 5-6
Variety selection
European plums, per Cornell Cooperative Extension:
- Stanley: The most widely grown European plum in the Northeast; self-fruitful; good for fresh use and prunes; zones 4-7
- Italian Prune: Self-fruitful; classic for drying; zones 5-7
- French Prune (Agen): Excellent for drying; zones 5-9
- Bluefre: Large fruit; self-fruitful; productive; zones 5-7
Japanese plums, per Oregon State Extension:
- Santa Rosa: Self-fruitful; widely adapted; zones 5-9
- Methley: Self-fruitful; early season; zones 5-9
- Shiro: Yellow fruit; requires pollinator; productive; zones 5-9
- Satsuma: Blood-red flesh; requires pollinator; zones 5-9
For the eastern US home orchard, European plums (particularly Stanley) are often recommended as a starting point because of self-fruitfulness and disease tolerance, per Penn State.
Rootstock selection
Per Penn State Extension:
- Myrobalan (P. cerasifera): Standard to semi-standard size; good anchorage; tolerates wet soils
- St. Julien A: Semi-dwarfing (50-60% standard); good for heavier soils; widely used for European plums
- Pixy: Dwarfing (30-40% standard); requires good soil and irrigation; productive
For home orchards with limited space, St. Julien A or Pixy are practical choices.
Light requirements
Per Cornell Cooperative Extension, plums require full sun — 8+ hours per day. Adequate light reduces disease incidence and is required for good fruit development and color.
Pruning
Per Oregon State Extension, train plums to an open-center vase form. Prune in late winter (February-March) before bud swell. Key practices:
- Keep center open to sunlight and air circulation
- Remove crossing, dead, and overcrowded branches
- Thin shoots to prevent overcrowding of bearing wood
- Cut back vigorous upright shoots
Per Oregon State, plums fruit on both short spurs and on one-year-old wood. Maintain a mix of spur-bearing older wood and vigorous new growth.
Timing note: Per Michigan State Extension, in the Pacific Northwest and other wet-winter regions, pruning during wet conditions increases susceptibility to fungal disease through wounds. Prune in dry weather or early spring when weather is clearing.
Fruit thinning
Per Penn State Extension, thin plums to 3-4 inches between fruits approximately 4-6 weeks after petal fall. European plums are less prone to heavy overcropping than Japanese plums, but thinning still improves fruit size and quality significantly. Japanese plums often set very heavy crops and need aggressive thinning.
Disease management
Brown rot (Monilinia fructicola): Per Cornell Cooperative Extension, the most common disease affecting plums, particularly Japanese types. Infections begin at bloom and continue through harvest. Management:
- Fungicide sprays from petal fall through preharvest (captan, myclobutanil, or propiconazole)
- Remove mummified fruit remaining on trees through the winter
- Improve air circulation through pruning
Black knot (Apiosporina morbosa): Distinctive black, elongated galls on branches, particularly common in the Northeast and Mid-Atlantic per Cornell Cooperative Extension. Management:
- Prune out infected branches 6-8 inches below the visible gall
- Burn or bag pruned material (spores spread)
- Preventive fungicide (lime sulfur or myclobutanil) from bud swell through first month after petal fall
Plum curculio (Conotrachelus nenuphar): Weevil that scars fruit with a crescent-shaped cut and deposits eggs. Per Cornell Cooperative Extension, control requires insecticide (carbaryl or spinosad) applied at petal fall and again 10-14 days later.
Common problems
| Symptom | Likely cause | Fix |
|---|---|---|
| Black warty galls on branches | Black knot | Prune 6-8 inches below gall; burn; fungicide program |
| Brown rot on fruit | Monilinia | Fungicide from petal fall; remove mummies |
| Crescent scars on young fruit | Plum curculio | Insecticide at petal fall |
| No fruit set (Japanese plum) | Pollination failure | Plant compatible pollinator |
| Small fruit; heavy drop | Insufficient thinning | Thin to 3-4 inches between fruits |
Frequently asked questions
Can I grow European and Japanese plums near each other as pollinators? Per Oregon State Extension, European and Japanese plums generally do not cross-pollinate effectively — they bloom at different times (European later, Japanese earlier). Plant pollinators within the same type. European plums: Stanley + Italian Prune is an effective combination. Japanese plums: Methley + Shiro or Santa Rosa (which has some self-fruitfulness) work well.
What is the difference between a plum and a prune? Per Penn State Extension, "prune" refers specifically to European plum varieties that can be dried without fermenting at the pit. All prunes are European plums, but not all European plums are prunes. The distinction is in flesh-to-pit ratio, sugar content, and the ability of the flesh to dry without the pit being removed.
Is black knot serious, and can I stop it? Per Cornell Cooperative Extension, black knot is chronic and persistent in the Northeast and Mid-Atlantic. Once established on a tree, it must be managed annually. Pruning out infections promptly (before spores spread in wet spring conditions) combined with a fungicide program at the right timing controls it but rarely eliminates it. Trees with severe systemic infections may need to be replaced.
When do plums fruit after planting? Per Penn State Extension, plums on semi-dwarfing rootstocks (St. Julien A) typically produce their first crop in year 3-5. Standard-rootstock trees take longer. European plums tend to be slightly later to first bearing than Japanese plums on equivalent rootstocks.
Sources
- Penn State Extension — Plums in the home orchard
- Cornell Cooperative Extension — Plum production and disease
- Oregon State Extension — Plum varieties and pollination
- Michigan State Extension — Stone fruit pruning