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Beach plum shrubs are beautiful. They are tough plants and they produce delicious fruit. These shrubs, with their showy white blossoms and vibrantly coloured fruit (in shades of blue, purple, crimson and yellow) were once prolific in coastal areas of the US and Canada. But in recent decades, most coastal land has been developed and now it's hard to find patches of beach plums in the wild.
And yet, growing beach plums (Prunus maritima) is possible almost anywhere. They tolerate poor soils and cold climates. In the interview below, Ken Asmus of Oikos Tree Crops of Kalamazoo, MI. explains how to grow beach plums, what conditions they need, and how to eat the fruit!
To listen to the entire, hour-long interview, listen to episode 21 of The Urban Forestry Radio Show and Podcast below.
KA: Well, they actually inhabit a narrow band along the Eastern Sea Coast of the United States of North America. Beach plums prefer a very sandy, open environment, and very low organic soil.
KA: They can. It's a fairly adaptable plant. It can grow in different types of soils, but it is a type of plant that prefers an open, sunny habitat. It also probably benefits from the moisture coming from the ocean, the salty air and other related things related to pollination. And also, beach plums prefer a cooler climate.
KA: Traditionally, beach plums were used to make jam or jelly or drinks. And because it's a more tart plum, it never really caught on as a plum that you would consume fresh. So it lends itself to processing. And that's where it really has been for hundreds of years.
People still collect it as a wild species plum, just like in other parts of the world. There might be Mirabelle plums in France that are collected wild that they make a specific jam or jelly or a drink from. Or maybe in the South, they would collect and grow Chickasaw plums.
The beach plum happens to be unique in that it's a shrub species. And it's just one of the most productive and diverse seedling groups that I've ever grown. So, that's makes it unique.
KA: There are some that have a skin on them that isn't as stringent, that is sweeter and can be consumed fresh, and some people enjoy them that way. But most beach plums have some astringency in the skin itself. That's part of the flavour profile of the beach plums. But generally, because you're cooking it and adding sugar, that is less of a concern.
KA: They don't seem to suffer. There's no black knot with beach plums. At least in the history that I've been growing them there's never been black knot. But in wet years beach plums may have some issues with rot forming on the fruit as they develop. It's very rare, but it does happen. And maybe some mildew on leaves, some years when there's a lot of moisture in the air throughout the summer. But that's about it.
There's no insect damage to the fruit itself. Very minor. The plum curculio, which is a big problem in other plum trees, tries to infest the beach plum. But the skin is too tough so nothing really gets into the fruit. The fruit is very clean and very easy to grow in that respect.
KA: When I first started planting beach plum seedlings, I was buying them from a company in New Jersey that had one year seedlings. So I planted the one-year seedlings, and they began to flower and fruit two years later. If you are planting the seed or pit of the beach plum it may be more like three to five years before it produces fruit.
KA: That's another great history of the beach plum, because it goes back to Luther Burbank who actually created varieties. And other people have since created varieties of beach plums. They found certain ones with attributes that they liked, and they would graft them or root them, bring them into an orchard, and then these plants would fail. They would not produce much fruit. Or there would be fruit one year and none the next. And they couldn't understand this. This has been repeated a number of times.
There are still a few cultivars available. I think I've seen a couple listed recently, but it's very rare, if not impossible to get. I started to graft some of them. And what I found was, because the beach plum plant produces profusely for about 10 years, then that stem will die. And then a new sprout will come up from the base. So the root system will continue to produce fruit. So, if you had a grafted tree, what would happen is the graft would die eventually after so many years and then a new sprout would come up, but that wouldn't be the original graft.
Yes. We've had requests for fruit. In fact, someone had bought quite a bit of fruit from us. One year we shipped it and they were experimenting with wine. You can easily make a good wine from beach plums.
KA: I think it's not self-pollinating most of the time. I really don't know what the percentages are, but I've read studies on beach plums pollination. And they've even found male and female plants of beach plums, which is very unusual. So there is an unusual pollination issue.
I think the beach plum is much like the oak tree in terms of pollination. Oak trees often will accept pollen from neighbouring trees and create a certain amount of acorns. But they'll also accept pollen from more genetically diverse plants, which will then increase the fruit set even more. I think that the beach plum is like that, in that you have this cross-pollination between two individual plants, and that might be sufficient. But if there are other beach plums nearby, and there's added bonus of more pollen of different types, that will increase the fruit set.
So normally, when people plant our beach plums, they plant two of them. For now it appears sufficient. Rarely will someone say they don't have fruit set. You really do need some cross-pollination, I believe, to achieve fruit sets.
KA: There's a certain range of adaptability with these plants. You can take a plant that has a rather limited range in terms of the climate and soil and move it somewhere else and it'll still be productive. I've had requests for seeds of these from all over the world in places that nothing would grow. They were trying to find a fruiting plant that would grow in pure sand. And so you wonder, "Okay, if it's going to grow in pure sand, can it grow in clay or something else?" The beach plum seems to be fairly adaptable in that respect.
To listen to the entire, hour long interview, listen to episode 21 of The Urban Forestry Radio Show and Podcast
Susan Poizner is an urban orchardist in Toronto, Canada and the author of Grow Fruit Trees Fast and Growing Urban Orchards. Susan trains new growers worldwide through her award-winning fruit tree care training program at Orchardpeople.com. Susan is also the host of The Urban Forestry Radio Show and Podcast and an ISA Certified Arborist.