About this Fruit Tree
Plum trees are one of the hardiest and most reliable fruits for growing in our region. Plum trees offer a nice assortment of fruits that have smooth skin, are deeply colored and contain a small pit. Fruit colors range from yellow to deep purple, and the fruit’s flavor varies, too. There are Japanese, European and American types of plums.
Plums are a stone fruit, like peaches and nectarines. In most cases plum trees need cross pollination to ensure a good crop of juicy plums. For cross pollination, plant a second plum tree, of the same type but a different variety. For example, plant a Japanese type with another Japanese type plum or a European with another European plum. American plum or Western sand cherry will pollinate as well. Plan for semi-dwarf plum trees to grow to about 15’ wide by 15’ tall.
How to Grow Plum Trees
Like other fruit trees, plum trees need full sun and rich, well-drained soil. Plum blossoms can be damaged by late spring frosts, so plant trees on slopes or elevations higher than the surrounding area as a method of frost protection. Avoid planting in warm microclimates, like the south and west sides of buildings.
Select a sunny spot in the landscape and prepare the soil so it’s well-drained. Plum trees can grow in clay soils, but it’s best to amend the soil deeply with an organic amendment, like compost or well-aged manure. The best soil for fruit trees is one that allows for good air and water circulation. For sandy or loamy soils mix about 1/3 compost with 2/3 native soil for good drainage.
Dig a saucer-shaped planting hole that’s shallow, but wide, and also amend the backfill before the tree is planted. Make sure the hole is no deeper than the root ball. Planting too deep slows root growth.
To prevent problems in the future, give your tree the best start possible. Keep in mind these planting tips to reduce transplant shock and to encourage root growth:
- Plant the tree at least a foot away from the lawn area.
- Set the root ball on undisturbed soil 1-2 inches above the soil grade. Give roots plenty of oxygen and make sure there is no backfill over the root ball.
- Make sure the crown of the tree (where the tree trunk meets the tree roots) is above the soil line.
- Fill in around the root ball with the soil removed from the planting hole.
- Mulch over the root ball (keep mulch away from the trunk) and around the tree to maintain soil moisture and help eliminate weeds.
- Water newly planted trees deeply, but infrequently.
Fruit trees take time to grow and newly planted trees might not yield much fruit. The yield of fruit crops on older trees may also vary from year to year.
Be patient and continue to care for trees through the year, which may include watering during dry winters. Water once or twice over the winter when the temperatures are above 40 degrees and there is no snow cover. Water early in the day so it soaks in before freezing overnight.
Keep plum trees watered through the summer, especially when the plums start growing. Water slowly and deeply to make sure water soaks in well. A layer of mulch that extends to the tree’s drip line will help maintain soil moisture and improve fruit production.
Plum trees can benefit from an annual fertilizing, right after blooming. Use a well-balanced fertilizer for fruit trees.
When plums start to grow, thin to about one every 4-5 inches on each branch for larger fruits.
Once plum trees are established, prune in late spring to maintain an open center. This type of pruning helps sunlight get to the interior of the tree.
Special Considerations for Growing Plum Trees
Plums can be affected by the same plant diseases and insect pests as other fruit trees.
Peach tree borers often attack plum trees on the tree’s lower trunk. Control borers starting in early July with permethrin or a similar insecticide. Follow all label instructions carefully and spray only the trunk (not the fruit or leaves).
Pear slugs also harm plum trees. These slugs come from sawflies and they suck the juices from leaves. A good control is to dust leaves with wood ashes or spray with a general purpose insecticide to kill the larvae.
Protect ripening fruits from birds by covering the tree with orchard netting.
Harvest plums when the fruits still have the dusty-white coating on the skin called wax bloom. Japanese plums are picked when they’re a little under ripe; European plums are harvested when soft and pass the taste test.
Clip fruits carefully from the tree to avoid harming the branches that produce fruit buds and allow the tree to grow fruit the following year.
Materials for Plum Tree Success
- Spade or shovel
- High-quality compost or well-aged manure
- Permethrin, general insecticide or specific treatment
- Soaker hose or other method for deep watering
- Orchard netting
- Tree pruners and clippers