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Blackberries are a powerhouse of nutrition. According to the Oregon Raspberry and Blackberry Commission, blackberries are astonishingly high in antioxidants as well as anthocyanins. They are easily grown but can easily take over an area if they are not taken care of, as they are fast-growing brambles.A few tricks can be used to increase your blackberry harvest as well as the quality of your fruit.
Prepare your soil by enriching it with well-rotted compost. They like to have a pH level of about 5.5 to 6 for the best growth. Make sure the site you have chosen gets full sun for at least 6 hours a day and is not in a low area that might collect water. Most soils are fine as long as they have good drainage. If your soil is a heavy clay type, add sand and organic matter to lighten it up. Use a pitchfork to turn over the soil and work in the added materials.
Make sure you are planting a blackberry bush that is virus-free by getting it from a reputable source and then keeping it away from any wild plants that might be carrying diseases. Another important detail is to make sure you have not grown any of the nightshade plants such as tomatoes, peppers, egg plants or potatoes nearby. These carry root viruses that can damage the blackberries.
Keep the moisture level high for the blackberry plant's roots. Although they need good drainage, they also need constant access to water. It is helpful if you plant them near a water source so you can easily water them during the dry hot days of summer during fruit formation. Mulching them heavily with grass clippings will also help keep the soil from drying out.
Prune your blackberry bush canes at least once every summer after they have finished fruiting. These brambles will grow leafy canes every spring that don't produce fruit until the following year, so don't cut them off. Instead, look for the canes that have finished fruiting, and cut them back to the ground. You should be able to recognize them by their brown bark compared to the green bark of the new canes.
Trim your blackberry canes at the top once they reach about five feet in height. This will force them to grow lateral shoots or side shoots. You can trim these back in the early spring so there are just three or four growing buds per shoot. Keeping the bush maintained like this will prevent it from turning into a large mass of tangled branches.