Days to germination: Plums are planted as seedlings
Days to harvest: 3 to 5 years after planting
Light requirements: Full sun
Water requirements: Watering during dry spells
Soil: Fertile and well-drained
Container: Possible in warmer areas only
For a tree, plums grow fairly small and work particularly well in the small backyard. They have a wide range of temperature tolerances, and you can choose varieties for zones 2 and 3 down to zone 7. Plums are hardy and durable trees that make a great place to start for a home orchard, especially in cooler areas.
The fruit is often eaten raw, though some varieties are better used in baking or other cooked uses. They’re one of the few fruits that are commonly dried commercially, at which point they are known prunes. They have vitamins C and A, and dietary fiber as well.
Starting Your Tree
When you are selecting a plum variety, be aware that most ornamental plums will not produce any fruit. They are grown for the looks only.
While you can get pure plum seedlings, most trees available are grafts. That means the top part of the tree has been “grafted” or attached to the roots of a different tree. This will have no bearing on your fruit production or quality.
To get the best fruit crop, you should plant at least 2 plum trees to get good pollination. Some varieties are self-fertile so you can get away with a single tree if you get the right type. Even self-fertile trees will give more fruit with a pollinator nearby though. Keep them within 50 feet of each other, but no closer than 10 feet.
You’ll want to plant your plum tree in the fall. Dig the hole large enough to comfortably hold the root ball, and add some compost or aged manure in while you are digging up the soil. After planting layer on a heavy application of mulch. Plums have shallow roots and don’t compete well with weeds. Make sure there is no other plants growing around the base of your tree.
Once established, your plum trees won’t need too much care other than a bit of pruning and a feeding of compost each spring. You should only need to water your plum trees when there has been a prolong spate of dry weather. Add more mulch each year if necessary.
Because of the shallow roots, plums do tend to put up shoots or “suckers” around the base of the tree. Cut them or break them off as they just take away from the productivity of the main tree.
Plums can sometime produce more fruit than they can actually handle, and that can lead to broken branches or just smaller fruit. If your plum trees are too overloaded, you will have to pick off some of the extra in order to let the rest develop well without harming the tree. Once the fruit is more than half-sized (roughly mid-summer), pick enough so that none of the remaining fruit is close enough to touch once another.
For pruning, you want to remove any dead or downwardly growing branches. Any suckers that sprout on the branches can be cut off as well. They will be very green and grow straight up, you can’t miss them. Each year, cut back the tallest central branch to encourage the tree to grow sideways instead of up. It makes for easier harvest and more fruit budding potential. Unlike most other fruit trees, it’s better to do your pruning in June rather than wait until the tree is dormant.
There are a few dwarf varieties of plum (such as St Julien A or Pixy) but they are not as cold-tolerant as other plum types. So if you want to grow plums in a container, you will have to be in an area no colder than zone 5. Plant in a 10 gallon or larger container, and keep it well pruned through the growing season. Water your plum tree often during the summer, and feed at least once per year with compost or standard fertilizer.
Pests and Diseases
Overall, plums are quite hardy and will likely give you no problems. But still keep an eye on your trees to catch the pests when they first appear.
If you see small holes dug into your new plums, it may be the larvae of the plum sawfly. They lay their eggs in the blossoms, and the worms eat the fruit as they grow. To control the problem, you will have to spray your trees before you actually see any damage. Spray the tree with an insecticide spray just as the blossoms are starting to fall from the tree. This will kill any eggs that have been laid before they can hatch.
Aphids can also be a problem with plums, though they are generally harmless in small numbers. Too many of them will cause the leaves to brown and fall off. Insecticides can help, and you can also release purchased ladybugs into your yard to help control the aphids (the ladybugs are predators of aphids).
In terms of disease, you need to watch for large black growths on the smaller branches. This is black knot fungus, and should be cut off immediately. Cut the branches about 5 inches farther down than the knots, to get all of the fungus under the bark. Dispose of the knotty pieces, don’t just toss them on the compost pile or the spores will just continue to reinfect your tree. Treat the tree with a fungicide, and repeat treatment in the spring each year as a preventative.
Harvest and Storage
Plums will usually start to produce fruit when they are 3 to 5 years old. Not all varieties of plums turn quite the same color at ripeness, so that’s not always a good way to judge. Your fruit should be slightly soft to the touch when ready to be picked.
You will get your harvest towards the end of the summer, usually over a period of several weeks.
It’s best to store fresh plums in the fridge where they will keep for 4 or 5 days. You can store them a bit longer if you pick them just before they are fully ripe, and store them in a cool dark place. They should keep for up to 2 weeks this way.