Edibles Grow Sheets

Plum Tree

• Scientific Name

  Japanese: Prunus salicina and European: Prunus domestica
• General Information

  

  

  

  Plum trees are easy to grow and have few pest problems. Two kinds of plums grow in California: European and Japanese. Within these, there is a huge variety, including black, purple, red or green skin, red or yellow flesh, and flavors from super sweet to semi-tart. 

• When to Plant

  Buy bare root in mid-December to late February. Keep roots in a moist medium until planting time. Six rootstocks are available, each adapted to different soils. Choose the rootstock that best matches your soil.

• Planting

  Learn more about planting bare root trees.

• Soil Requirements

  Plum trees are tolerant in many types of soils, but do best in soils with ample organic matter and good drainage.

• Water Requirements

  Plum trees are intolerant of shade and drought. Depending on the weather, provide about three feet of water during the dry season. Water every two to three weeks. Drip irrigation around the branch circumference of the tree is a preferred method for irrigation.

• Fertilizing

  Spring: Begin to fertilize large mature trees when they start to push foliage out in the spring. Use a balanced organic fertilizer in the range of 16-16-16, available at your local nursery. Follow directions on the box.

  Summer: Fertilize young or newly transplanted trees monthly to encourage good strong growth.

  Autumn: Fertilize mature trees just after harvest. Water well.

• Pollination

  Many varieties require a compatible pollinator to ensure good fruit set. Be sure to determine this before you plant, since the pollinator variety will need to grow in close proximity or be grafted onto a branch of the tree you select.

• Harvesting

  Harvest the fruit when it is firm ripe. Fruit of early varieties may need to be harvested over a period of weeks, while that of later varieties can usually be harvested all at once.

• Storage

  Store plums in the refrigerator to maintain optimum quality. Plums may also be sun-dried, canned, or frozen. Dried plums (prunes) can last for a very long time. For best results, use a dehydrator. The European plum is the ideal variety to use to make prunes because these are smaller, denser, and less juicy than the Japanese varieties.

• Good Varieties for Marin

  Many types of plums thrive in Marin. Low chill types are preferred. These are usually of the Japanese variety. Dwarf plum trees may produce fruit sooner than standards.

  Chill hours requirement for plums range from 300 to 800 hours below 45 degrees F.

  Plum trees that do well in Marin and require about 300 chill hours: 'Santa Rosa' 'Satsuma' ‘Mariposa’

  Prune plums require approximately 800 chill hours: 'French' and 'Italian' (both are good for drying).

• Helpful Tips

  Most plums tend to overbear, so be sure to thin the fruit. In spring, thin the fruit to about four to six inches apart when they are one-half inch to three-quarter inch in diameter. If you want to produce larger mature fruit, leave even fewer immature fruit on the tree.

  Pruning:

  Winter: On mature trees, prune out any dead, diseased, or broken branches. Thin branches out (usually 20 percent of last year's growth) to allow good light penetration into the tree. The purpose of thinning cuts is to reduce crop load and increase light penetration. Do not make heading cuts that shorten the tips of the shoots.

  Summer: In late June or early July, remove the strong, vigorous shoots from the interior portion of the canopy to improve light penetration and air circulation in the tree's interior.

  Learn more on pruning plum trees.

• Common Problems

  Several pests and diseases may affect the health of plum trees, including codling moth, peach twig borer, and bacterial canker.

  Plum aphids often cause curling of the young leaves in spring, but you only need to control them when 50% of the leaves are curled and live aphids are present. Insecticides are not required. If aphid populations become intolerable, control with insecticidal soap or Neem oil.

  Branch breakage due to fruit weight may occur. Thin fruits or prune branches for a stronger structure.

  Besides some tree diseases, birds and vertebrate pests such as squirrels, gophers, rabbits, rats, voles, and deer may damage or reduce fruit yield. Use bird netting and fencing to reduce their access. Vertebrate control equipment is available at retail outlets but some pests are protected. Check with your local Cooperative Extension before trapping or removing vertebrate pests.

• Pests- Diseases & More

  Learn more about growing plums.