Answer: You may find that it takes a year or two for the plants to settle in and become established and productive. They need full sun and evenly moist yet well drained soil. Using a layer of organic mulch can help keep the soil moister during dry spells. You would also need to deep water (do not use overhead watering, avoid wetting the foliage) them during any summer dry spells. These plants do not require heavy fertilization. If oversupplied with nitrogen, they may grow luxuriantly but produce little fruit.
Boysenberries produce on the canes that grew the year before, meaning the old canes. Each year right after harvest, remove the older canes that produced the berries by cutting them off at the ground. This encourages the newer canes to develop for the following year's production. Do not prune them back for the winter, or in the spring as this would remove your fruiting canes for the coming year.
Although considered hardy to zone 5, you may find that these plants suffer extensive winter damage in your area. If this happens, the crop will be reduced. To try to protect the canes, some gardeners untie the plants and lay them flat on the ground, then heap straw over top of them for the winter. Your local county extension may also have some suggestions, but I hope this helps.
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