Boysenberries are juicy and sweet, like a blackberry, but can have a tart aftertaste, especially when not fully ripe. They require full sun and shelter from the wind and, like other trailing vine fruits, they require regular pruning. When selecting boysenberries, look for ones that are plump. Boysenberries don't keep long, but should be stored in the refrigerator in a shallow, covered container. Do not wash them until just before eating, as the moisture can hasten spoilage.