The best time to plant a plum tree is twenty years ago. The second best time is now.
-“Chinese proverb” (probably not though…)
We have two Japanese plum trees in our yard. The cultivar names are confusingly but unmistakably Slavic: Ivanovka and Ptitsin #3. The trees were purchased as cuttings from the University of Saskatchewan, but the varieties were first developed at the Morden Research Station in Manitoba and first released in 1939. We chose these specific varieties for their cold-heartiness, fruit quality, and pollination requirements.
For most of our other fruit trees we didn’t have to give much thought to pollination. Our sour cherries, for instance, are all self-pollinating. And while apples must be pollinated by another genetically-distinct member of the genus Malus, there are so many apple trees in Edmonton this is a non-issue.
Plums on the other hand are not self-pollinating, not super common in Edmonton, and actually quite picky about who they will allow to pollinate them. If you plant a single plum tree in Edmonton, even if the variety is cold-hearty, it will not likely produce fruit unless you take active measures to get it pollinated. The two major factors are the species of your plum and the flowering period.
One – Species
There are three species of plum and several hybrids that are hearty enough to grow in the Canadian prairie provinces. They are:
- the so-called “wild plums”, which refers to two species: Prunus nigra (“Canadian Plum”) and Prunus americana (“American Plum”)
- Prunus salicina (“Japanese Plum”)
- the hybrids of one of the wild plum species and Japanese plum (ie. either P. nigra x salicina or P. americana x salicina). Common varieties here include Pembina and Patterson Pride.
These three species and their hybrids have rather confusing pollination compatibility.
- P. salicina can be pollinated by either another P. salicina, or a wild plum.
- Hybrids do not pollinate other hybrids. Nor do they pollinate P. salicina.
To maximize our yield of high-quality fruit we elected to plant two P. salicina. But this brings us to the second important part of the plum-pollination-equation…
Two – The two compatible plants need to flower at the same time!
After researching eating quality and pollination compatibility, we struck up Ivanonka and Ptitsin #5.
We drove to Saskatoon for the University of Saskatchewan fruit sale. We left with two of each variety. We paid $5 for each specimen. These were cuttings, so they were single sticks about 6″ long in little plastic pots.
Early Life. The plum trees were planted in the middle of a patchy weedy lawn. I call this the “Boy Named Sue” theory of cultivation: intentionally give the young plants a difficult upbringing to make them strong. If it weren’t enough that they were in a weedy patchy lawn, the spring after they were planted they were eaten down to the ground by jackrabbits, which I write a bit about here. It was devastating, but amazingly they sprung back.
Four years after planting we saw our first flower. In retrospect this makes sense as they only flower on growth that is two years or older, and the jackrabbits had set us back a year. Also at this time some of the varietal growth habits started to show, with the Ptitsin having very wide branch angles and a very elegant, open vase shape, and the Ivanovka much shorter angles and a more vertical habit.
In the fifth year we got our first fruit! A modest harvest to be sure: two Ivanovka plums and one Ptitsin. Still, we were ecstatic.
There are a lot of eating-quality notes on these plums online, but I think many of the authors are more accustomed to bananas and strawberries from the supermarket than interesting cold-hearty fruit. If ripened properly Japanese plums are emphatically not sour: they are absolutely delicious and perfectly balanced. For now we are eating them out of hand. We are beyond excited for yields to increase so we can try plum pot, plum wine, plum jam, powidltascherln, prunes, stewed plums, zwetchenknödel,….
- While we fully intended to purchase a Ptitsin #3, after having seen the growth habit and fruit of this plant, we are pretty sure we somehow ended up with a #5.
- This info and all the following info on plum species, hybrids, and pollination are from this handy document from the U of S.