There are literally hundreds of varieties of plums grown in Canada, some commercially, many experimentally, but even more in home gardens. Thanks to the overall hardiness and adaptability of plums, they’re second only to apples in popularity in Canadian gardens. No matter where you live in this country, chances are there’s a plum you can grow.
Although the word “plum” instantly brings to mind the fruit, don’t forget the tree’s ornamental value. Plums bear sweetly perfumed, white flowers in early spring and, being of fairly small stature, they aren’t likely to interfere with power lines. Bush plums can be used as hedges, foundation plants or low windbreaks. The fruit also attracts wildlife to the garden, although that may not be your goal if you want to harvest the fruit yourself. Fall colour is not the plum tree’s strong point, though: most cultivars produce leaves that turn yellow only very briefly in autumn, then drop off.
It’s always best to find a local supplier of plum stock, if possible, as they can be very capricious plants, doing well on one side of a valley and not on the other. Unfortunately, you won’t know they’re doing poorly until three to five years after planting, when they should start to fruit. Ask a local plum grower (the best question: If you had to start all over again, which plums would you choose?) or a nursery employee with experience growing plums.
Most plums sold today are grafted, but home gardeners in severe climates would do better to choose own-root plums. That way, if it dies back to the ground during an abnormally cold winter, the tree that sprouts from the base will be the chosen variety. In cold climates, cover the graft union with about eight centimetres of soil so the tree can produce its own roots. (Plums are grafted at the base.)
A cross between American plums and bush cherries (small-fruited, shrubby plums), cherry types bloom a bit later than most plums so are more likely to survive a late spring frost. They’re about three metres tall and bear small, red fruit with yellow to red flesh. ‘Convoy’, ‘Opata’ and ‘Manor’ do well in Zone 3.
Plums do best in rich, moist but well-drained loam or clay loam in full sun. Anything that will delay their blooming will be useful in areas where late frosts are likely: a large body of water, large snowdrifts that melt slowly or a site on the north side of a hill.
Most plums are grown as trees, although the American species can also be grown as a shrub. To create a solid, productive tree, prune out weaker branches and lightly cut back a few stronger ones in spring for the first few years. This will force branches to grow in girth rather than length and to form a solid trunk. After two or three years, the tree should be well formed; after that, simply remove water sprouts, cut back overly vigorous leaders or branches, and thin out weak or crowded growth to ensure good air circulation. Since plums produce fruit on spurs (short sprouts that remain active from year to year), don’t methodically prune out only old wood, although less productive wood can be removed.