Back in the 1920s, Rudolph Boysen started crossing various cane fruits. He used blackberries, dewberries, loganberries, and raspberries to create a hybrid. It didn’t grow well, and he abandoned the idea. Those canes were rescued by Walter Knott, of Knott’s Berry Farm fame, a few years later. The rest, as they say, is history.
You generally won’t find boysenberries in stores because they are so juicy and thin-skinned that they start leaking delicious juice within a day or two of being picked. But boysenberries are easy to grow and provide extra-large, sweet-tart treats all summer.
When shopping for a boysenberry plant, you can select thornless (Rubus ursinus var. loganobaccus) or non-thornless hybrid (Rubus ursinus × Rubus idaeus). Please note that “thornless” is not a guarantee. Thornless varieties generally have fewer thorns than their cousins. And thornlessness can be genetic, hormonal, or created in a lab. Genetically thornless boysenberry plants will stay that way. The others may not.
Like other hybrid plants, boysenberries are not grown from seed. You can try, but you are unlikely to get an edible boysenberry.
Boysenberries are best grown in USDA Hardiness Zones 5-9, though you may be able to manage in Zone 4. They prefer full sun, soil pH of 6.0-7.0, and good drainage. Boysenberry roots are perennial and will fill spread using underground stems called rhizomes, so plan accordingly.
You can buy dormant bare-root boysenberry plants. You can also use root cuttings, root division, and tip layering. As with any new plant, put your boysenberry into quarantine before adding it to your landscape.
Caring for boysenberry plants
Boysenberry plants only need to be fed when planted and again each spring. Like other brambles, you can let them grow wild or train them up a fence, stock panel, or trellis. Training your boysenberries makes pruning and harvesting a lot easier.
When your boysenberries have entered dormancy, prune first-year primocanes, leaving 5-7 per plant. Cut lateral branches back to no more than 12 inches. This pruning will reduce the risk of pests and disease while making room for the next batch of canes.
If you live in a cold climate, cover your boysenberries with a thick blanket of straw in winter and use a dark mulch. If you live in a warmer region, apply light-colored mulch and provide a little afternoon shade.
You can grow a surprising amount of food in your own yard. Ask me how!
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