This delicious species of berry is the product of an interesting hybrid of already-hybridized parents. The genetics of the boysenberry aren’t entirely known but suggest evidence of loganberry, raspberry, blackberry, and dewberry in the family tree. Being a fruit-bearing woody vine (after one year of maturation), a trellis or support structure is advised. The art of trellising the vine will make for an easier way to sift through the bramble while picking berries and allow for a beautiful visual of vines and berries in any garden or landscape. The fruits are thin-skinned and do not transport well, so eat them quickly once they’re ripe.
Despite its name, the Thornless boysenberry does have thorns, but they’re smaller (more like thin hairs) and less in number than found on the Thorny variety. Said to be less hardy than their prickly cousin, Thornless boysenberry should still survive a winter in regions as low as USDA Zone 6, particularly if they are properly protected.
Seed: Boysenberry does not grow from seed.
Vegetative: Propagate by taking stem cuttings. Cuttings root in water or wet soil in 2 to 3 weeks. Boysenberry can also be propagated by layering.
Space Between Plants: 4–6′
Space Between Rows: 6–8′
Plant Outdoors: Best planted outside in late fall.
Grows best in a cool climate. This berry requires protection during winters that drop below -10°F, so we suggest that it not be grown outdoors below USDA Zone 6. Extremely dry climates are also not suitable for this berry as it prefers moist soil. New Zealand is currently the world’s top producer of boysenberries.
Natural: Full sun to partial sun depending on water availability and sun intensity.
Soil: Prefers a well-drained loamy or sandy soil with high levels of organic matter. A pH level of 6.0 to 6.5 will keep plants happy and healthy. These woody vines produce deep root structures, so proper soil tilling should be implemented.
Soilless: Will grow in most soilless media.
Hydroponics: Not much is known about growing boysenberries in a hydroponic system. If attempting to grow them in this way, however, it’s recommended that you use a deep water culture system to avoid the roots taking over too much space.
Water: Requires moderate to high levels of water. Prefers deep soakings 1–2 times per week rather than consistent but smaller waterings.
Nutrients: Requires moderate to high levels of nutrients. Till compost about half a foot deep and wide in the transplant hole to add nutrients to the soil. Use an organic meal fertilizer as soon as the growing season begins and again as flowers start to bloom and produce fruit. Fertilizer should be placed about a foot away from the base of the plant. A balanced fertilizer will benefit your bush, but it is particularly fond of phosphorous and sulfur, so it may be worth adding fertilizer high in these elements if you’re experiencing stunted growth.
Pruning: Each year after harvest, cut back about half the vine that you have plucked from. Do not prune off new branches. No existing branch should be over 4 years old.
Mulching: Use mulch to suppress weeds and maintain soil moisture. A light and airy mulch like straw can help to protect the roots of the plant during the winter.
Support Boysenberries have a difficult time supporting their own weight, so we recommend that you set up a 3-wire trellis system when transplanting. Set up two posts or stakes at either side of your plant and attach wire between them. The wires should be placed approximately 2, 4 and 6′ above the tops of your seedlings. As your plant grows, attach it to the wires with ties to help support them.
Companions: Grows well with marigolds.
Harvest: Spring and early summer bring visible fruiting. Wait for the berries to ripen to a nice dark purple. Plants will not bear fruit their first year.
Storage: Fresh berries do not store well, so use within 1 or 2 days of picking. Freeze berries that are not freshly eaten.
History: This berry was originally bred by Rudolph Boysen who actually abandoned the experiment and his farm before the berry became popular. It was picked up by the USDA and a farmer named Walter Knott who breathed life back into the plant and popularized it in the state of California.
Preserve: You can use boysenberries in you favorite jam or jelly recipe. Soak in lemon juice and sugar to make a delicious preserve that will last for months. Try dehydrating a thin layer of mashed up boysenberry pulp to make your own fruit leather.
Prepare: Pick and eat! Top your desserts, ice cream, or fruit salads with this berry. Also found in pie and cobbler recipes.
Nutritional: A good source of vitamin(s) C, A, B6, E, thiamine, folate, and fiber. Also contains the minerals manganese, potassium, copper, calcium, iron, phosphorus, and magnesium.
Medicinal: Due to its high levels of fiber, boysenberries can help with constipation and cleansing the digestive system. It is also high in antioxidants which may contribute to reducing the risk of many types of cancers.
Add a little sweetness to your breakfast routine by spreading some of this delicious Boysenberry Jam on your toast.