Thornless Blackberry Plant Care

Thornless Blackberry (Rubus canadensis) belongs to the Rosaceae family within the Rubus genus. Thornless Blackberry is native to central and eastern Canada and the eastern United States. Thornless Blackberry is also known as Smooth Blackberry, Dwarf Blackberry, Low Blackberry.

Thornless Blackberry displays a spreading, thicket-forming shrub growth habit, reaching up to 4 ft tall with a spread of approximately 6 ft. Thornless Blackberry produces white or pink five-petaled flowers in clusters.

Leaf size: approximately 4 inches.

Water a young or newly planted Thornless Blackberry every 3–5 days, soaking the whole root zone, until it is established — usually one to two growing seasons. Established shrubs mainly need water during long dry spells. In a container, water whenever the top few centimetres of soil are dry.

Thornless Blackberry thrives in full sun to partial shade.

Rubus canadensis tolerates temperatures of 50–80°F. Thornless Blackberry prefers humidity levels of 40–70%.

Well-draining loamy soil with added compost for nutrients. Good drainage is essential for Thornless Blackberry to prevent waterlogging, which leads to root rot and fungal issues.

Feed Thornless Blackberry every 6 months during the growing season with a balanced, slow-release fertilizer at the rate on the label. Established shrubs in good soil often need little extra feeding, so let weak growth or pale foliage guide you.

Stop feeding by late summer so new growth can harden before winter.

The PlantoScan app can remind you when to water and when to fertilize each plant.

Choose a spot with full sun to partial shade and well-draining loamy soil with added compost for nutrients. Avoid low spots where water collects after rain.

Thornless Blackberry is suited to USDA Zone 12a.

Plant container-grown or balled-and-burlapped shrubs in spring or early autumn, setting the root flare at soil level, and water well after planting.

Thornless Blackberry can spread to about 6 ft (1.8 m) and reach about 4 ft (1 m) tall. Space plants about 6 ft (1.8 m) apart so mature crowns don't crowd each other, and plant at least half that distance from buildings, fences and paths.

Planning a row or hedge? Try the plant spacing calculator.

Prune Thornless Blackberry while it is dormant in late winter: first remove dead, damaged and crossing branches, then thin lightly for shape.

If it flowers in spring, prune right after flowering instead so you don't remove next year's buds. Never take off more than about a quarter of the shrub in one year.

Thornless Blackberry is frost-tender (hardy to USDA zone 12). In colder areas grow it in a container and move it to a bright, frost-free place before the first frost.

Thornless Blackberry can be propagated through division, stem cuttings, layering. Similar propagation techniques also apply to black raspberry plant care, which shares the same genus.

See all plants toxic to cats and plants toxic to dogs.

Thornless Blackberry is susceptible to aphids, spider mites, raspberry fruitworm. Inspect the foliage regularly, especially along leaf undersides and stems. Treat infestations promptly with insecticidal soap or neem oil to prevent spread.

Yellow leaves, brown tips or drooping? See common plant problems and how to fix them.

Thornless Blackberry grows outdoors in USDA Zone 12a. It survives winters down to planting zone 12a. Thornless Blackberry is native to central and eastern Canada and the eastern United States. In cooler regions, grow Thornless Blackberry as a houseplant or bring it indoors before the first frost.