Blackberries make very tasty fruit pies, cobblers and smoothies. In the summertime when they are abundant in many parts of California, you can find loads of this succulent fruit, or you can easily grow them in your backyard. However, many wild blackberries are the invasive species Himalayan blackberry (Rubus discolor), which is native to Western Europe. This plant is a thorny invader, producing 30-foot-long canes every summer and choking out habitats where native plants are attempting to grow. It is recommended that you grow the native California blackberry (Rubus ursinus) or the cultivated varieties Prime Jim or Prime Jan, which are nonspreading and remain a more manageable size. You will be doing the environment a favor if you don't grow the invasive Himalayan blackberry.
Purchase a bare-root blackberry plant or two to ensure that you are not going to contribute to the spread of the invasive Himalayan blackberry.
Allow plenty of room in your garden for your blackberry, because they spread. Weed an area at least 4 feet by 8 feet if you will be planting two bare-root blackberries. Clear more space depending on how many plants you will be growing.
Dig in 3-gallon buckets full of compost or composted manure for an area that is 4 feet by 8 feet.
Dig one hole for each bare-root plant you plan to grow. Make sure it is a bit larger than the plant's root system and then place your young plant into the hole. Refill the planting hole with the soil you dug out and then water it thoroughly.
Water your blackberry regularly to maintain constant soil moistness, but do not allow your plant to sit in a puddle of water. Mulch can help keep the soil moist and will soak up excess water.
Fertilize with a standard plant food that is high in nitrogen just before the blackberry's active growing season---late winter or early spring is the right time to feed your plant. Give each plant ¼ lb. of nitrogen each year at this time.
Prune your blackberry during its winter dormant season by cutting off the lowest shoots all the way back to the main trunk. Prune canes that are 2 or more feet from ground level to 12 or 15 inches in length.