Gardeners who have ever harvested wild or homegrown blackberries owe a debt of gratitude to the breeders of the thornless blackberry. In the past harvesting blackberries required wearing long sleeves and pants and thick gloves, because blackberry thorns are vicious. Now, with thornless blackberries, a gardener can enjoy the wonderful taste without the pain. The even better news is the fruit of the thornless blackberry is sweeter and the berries larger than traditional blackberries, and the plant is more cold tolerant.
Select a site: The thornless blackberry prefers sun but will tolerate some shade. Allow for 4 feet between plants to allow for growth and airflow. The plants will reach 3 to 6 feet at maturity, so consider any shading implications in selecting your site. If you are planting multiple row of thornless blackberries, allow 8 to 10 feet between rows.
Prepare the soil: Blackberries are quite tolerant plants, and little special preparation of the soil is needed. They would like some compost or cured manure in the bed, and the soil should be well-drained. Blackberries need a neutral or slightly acid pH. If your soil is alkaline, increase the amount of organic matter and consider adding some sulfur to lower the pH.
Plant: Place thornless blackberry plants in the soil in early spring in the North. They are able to grow in hardiness zones 5 through 9. If you live in the South, plant your blackberries in the fall or winter. Set the plants into their holes at about the same depth as the growing container. They need to be planted deep enough to cover their roots, but no more. Add 1 to 2 inches of mulch around each plant.
Prune the plant back to about 6 inches. Water the soil and lightly fertilize.