If you live in a region suitable for growing both red and black raspberries, by all means, grow both fruits. Black raspberries, sometimes called "black caps," are hardy only to U.S. Department of Agriculture plant hardiness zones 5 or 6, while some other raspberry cultivars are hardy to zone 3. Whether or not you grow the two together depends on several factors.
You may have heard not to plant bramble plants together because they can spread diseases. Diseases are always a possibility, but are more likely if you transplant wild plants or diseased plants from a neighbor. Destroy any wild berry plants lurking on your property. Stick with nursery-purchased plants that are certified disease-free. and red and black raspberries will likely stay healthy for many years, even when planted together.
Both red and black raspberries need full sun and rich, well-drained soil. If you have plenty of room, plant red and black raspberries separately. Otherwise, plant them together in a sunny location with access to good soil and water.
Consider how you plan to trellis the plants before planting them together. Black raspberries have tall, arching canes that send out fruiting side branches. Like blackberries, they need some sort of support. Red raspberries, on the other hand, produce fruit on stiff canes and don't need a trellis. Many people prefer to grow red raspberries as a hedgerow. Additionally, if you grow primocane red raspberries and cut the canes to ground level each fall, plant them in a separate bed so you can mow them down after harvest.
Whether to plant red and black raspberries together is largely a matter of garden economics. If you can separate them, do so, simply because their growth patterns are different; otherwise, plant them together. Avoid planting raspberries where tomatoes, potatoes, eggplants and peppers have grown within the last three years, though. These crops can spread verticillium wilt to your berries.
- The University of Maine: Growing Raspberries and Blackberries
- "'The Garden Primer;" Barbara Damrosch
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