Blackberries are hardy plants that are relatively easy to grow. However, growing from seed won't produce berries the first year. The seeds require stratification the first year and will grow the second year. Blackberries are hardy plants that rarely contract disease or attract pests. There are two types of blackberry plants: trailing and erect. The erect type has a stiffer cane and is more cold hardy than the trailing. You can still grow the trailing in the colder climates with mulching and proper care.
Place damp peat moss in a sandwich bag and put seeds in the peat moss. Close this and put it in your refrigerator for 3 to 5 months. The temperature must be between 33 to 35 degrees F to stratify the seeds. The seeds should start to open up in the cold.
Plant the seeds in a flower pot with stones or broken terra cotta in the bottom for drainage. Use a soil made for fruit and mix it with compost. Keep the seeds moist until they start to sprout. Mix in more compost about every month and water when soil starts to feel dry.
Plant outside the next spring. Place the plants in full sun to partial shade in well-draining soil. Place a trellis behind the plants to help hold up their canes. Dig out the hole large enough so as to not bend the roots and mix soil with compost before planting the seedling. Plant the plants 2 feet apart with rows up to 7 feet apart. Keep mulch on top of the soil around the plants to keep out weeds and hold in moisture.
Keep canes trimmed to about 7 feet. In the second year, trim the canes that have produced berries to the ground and cut off suckers that have grown outside the rows.
Pick berries when they turn dark red or purple in color. Pick up any berries that fall to the ground.