If you’re just planting fruit trees for the first time, also look at the Learn to Grow Fruit Trees page.
Site Selection and Planting
- Choose a site that is in full sun. Plums and prunes are tolerant of many soil types, but will perform best on deep, well-drained soil. If your soil is very heavy and winter wet, consider building a mound for your trees, 4′-5′ wide, 16″ deep.
- Check pollination requirements. Japanese plums will not pollinate European plums or vice versa as they bloom 2-3 weeks apart. Some plums are partially self-fertile; those will produce more as young trees if planted with a pollinizer. Fully self-fertile plums can be planted alone.
- Because plum and prune trees bloom early, a site that does not get late frosts is best. Frequent frost during and after bloom will mean poor fruit set.
- Keep grass and weeds away from the tree to reduce competition. A very thin mulch can be used to keep weeds down.
- Irrigate thoroughly during the summer months, watering infrequently but deeply. It is especially important to water adequately while the fruit is approaching ripeness.
Visit our Disease and Pest Management for the Home Orchard page for general fruit tree disease and pest controls
- Remember the goal in the home orchard is to keep the trees healthy.
- Plums and prunes benefit from a delayed dormant spray of copper sulfate and oil, applied at stage 3 of bud swell when the bud scales have separated but are not yet showing petal color.
- During the spring and summer months, watch for aphids, and control with horticultural soap or a strong jet of water.
- If you have had Brown Rot (fruit rotting from the blossom end as it approaches ripe), spray copper at leaf fall, and micronized or wettable sulfur at stage 3 the following spring. Serenade Garden Spray and Monterey Complete Disease Control are also listed for brown rot. Remove dropped fruit from the orchard and dispose of it.
- A fall spray of copper can also help prevent Bacterial Canker.
- Black Knot (warty black growths on the twigs) can be a problem of plum and prune trees. It is spread by wind from other diseased trees. If possible, remove diseased trees from the surrounding areas. If black knot appears on your trees, spray sulfur at shuck fall. Remove any knots that appear by cutting below the growths during dry periods in the spring to remove them and destroy the wood.
- At planting, choose 3-4 evenly spaced branches to form the main trunks or leaders. It is best to choose branches that are not too upright. Ideally, the branch angle should be about 30°-45° (90° is horizontal, 0° is vertical). Remove all other branches and cut these trunks back to 18″-24″.
- The first summer, after 12″ of new growth, pinch all but two shoots from each branch.
- In the following years, remove broken or crossing branches during the winter season. Thin branches to maintain light penetration and reduce crowding.
- Keep the height of the tree in check by cutting back main branches to a non-fruiting lateral branch during the dormant season.
- In summer, remove water sprouts and suckers. Cut out any black knot.
Plums and prunes can have alternate years of light crops and heavy crops. During light crop years, it can be beneficial to pinch back or prune sprouts and suckers more vigorously as the tree is not spending as much energy producing fruit. In heavy crop years, it might be necessary to hand-thin the fruit after set. Fruit that is crowded and touching is more subject to brown rot. If thinning the fruit, removing fruit from the underside of the branches helps the remaining fruit grow without crowding. It is also sometimes necessary to support branches that have heavy fruit loads.
Fruit will shift color and go from hard to firm when approaching ripeness. The best ways to judge ripeness is by tasting, a slight squeeze for texture, or the dropping of fruit. Most plums will not ripen further once picked. Some plums will store a few weeks in the refrigerator but are best eaten or processed shortly after picking. When plums are ripe, birds, squirrels, and raccoons can become a problem. Flash tape or shiny material hung in the tree can help deter birds.