Plum Pollination article by Thean Phey


In my ungoing quest to actually get a decent harvest of plums off of my ever expanding hybrid plum and chum section I read whatever I can find about plum pollination trying to understand it. I realize I’m not alone in this situation (many trees, few fruit) and a lot has been said on GF, but there has to be a better way than just continuing to add varieties and hope for the best. This year should have been a bumper crop for me – only one frost in early June and 3 days of beautiful sunny weather when all of the plums and chums were in full beautiful bloom (the longest stretch we had with no rain all season) and they were full of pollinators. I had great expectations. I had a handful of fruit. The only trees that didn’t bloom were the, it sounds like, very important American Plums which are too young yet, plus some new grafts of even more hybrids. The only years (two) that I’ve had a somewhat reasonable crop I also had a Pembina blossoming. Unfortunately that tree died a few years ago.

This summer the newsletter of the Canada DGB Fruit Growers Group had an article by Thean Phey on Plum Pollination (I’m always on the lookout for articles by Thean Pheh and Bernie Nikolai for interesting ideas on growing fruit in colder regions). It doesn’t give any easy answers, no answers really, but it was interesting. I’m wondering what others more knowledgeable than I think about his ideas here? The plum article is down the page below the Budding and Grafting one.


Neay article and newslwetter, lots of interesting info in there! I also liked the piece on cotoneaster as understock for pear…
I use p Americana as pollinators for my hybrid plums and it seems to work out. At the plum trial at our cooperative extension farm, they have a small isolated block of Hansen hybrids and haven’t gotten good fruit set, I told them they needed to add in some p americana…


Wow, Sue, great information in those articles for the cold-weather types! I picked up a lot of tips on various subjects that I hadn’t come across before. Thanks!


I see plum pollination as having multiple factors and these factors vary with each growing zone, so a cure all for poor pollination in my opinion doesn’t exist. Plums seem to need to be fairly mature, maybe 5 or 6 years too before drawing any conclusions. I have good pollination here, it took 5 years. I don’t have any native plums either. I don’t have a lot of trees either, Satsuma, Nadia and 4 pluots. All fruited this year, first time ever. Most were loaded with plums. I have added about 8 more as grafts this year, so I need another 5 years before I can make good observations on them.
In the colder zones Konrad knows his plums he is on Garden Web, and won’t come here. I’m not in a warm zone, but not in zone 3 either so my experiences in zone 5b/6a only apply to those zones and only in the Midwest in my opinion.
I think the fact I grow many plants that attract bees, and other beneficial made the most difference for me. Flowering herbs, nasturtium, borage, zinnia, sedums, lily’s, raspberries, etc. My yard is buzzing with bees all year. And they come back looking every year too. Many solitary bees probably live in the yard now. Some research does support that they help in stone fruit pollination. Nasturtium,columbine and borage self sow, only planted once. I germinate Zinnias every year, I really like them, the flower lasts for weeks and it produces ton’s of them. Easy to harvest seeds too. The others are perennials.
One of the biggest attracting plants to native bees I have observed is strawberries, native to all of North America. And they flower early, right with the plums.


To muddy the waters even more… in a cold zone you can have significant damage to the female bits of the plum flower, but seemingly have fully functional pollen-shedding male bits. This has been my experience the last two years with my Suprerior and Alderman plums. Both years the majority of ovaries have been killed by spring freezes, but have had pollen and nectar, and have been visited by some sort of native mason or other native grey-colored bee. However, my fruit set has been bad because of the dead female parts.


Not much you can do, well you can heat them with lights etc, but I find that so impractical. I’m lucky as the lakes buffer those late freezes and most years we are good. Once in awhile a bad one happens anyway. I noticed last week at my cottage which is farther north than my house that it was warmer there. The lakes are warm and warm the local air. The cottage is 100 yards from the river. Warm is relative, say 50F or above the water is right now.