Shrub · Rosaceae
Blackberry
Rubus fruticosus
Give it full sun and room to arch, and a blackberry hangs its canes with dark, glistening fruit for years.
Full sun
Every 3–7 days
USDA 5–9
3–10 ft · 0.9–3 m
Overview
A blackberry is built from long, arching canes that sweep up and out before bowing back toward the soil, rooting at the tip wherever they land. It is a bramble in the rose family, and most plants line those canes with sharp, hooked prickles that catch the skin. Left alone, the canes pile over one another into a dense, tangled corner of the garden.
Look closer and the plant tells its age in its canes. A first-year cane grows as a leafy primocane, all green growth and no fruit, then returns the next year as a floricane that flowers and sets berries before drying out and dying. The two generations stand side by side in the same clump, one soft and growing, one woodier and fruiting.
The fruit itself is a tight cluster of small, glossy druplets, each a bead packed against the next around a central white plug. As they ripen through midsummer the beads swell and darken from red to deep black, and a ripe berry pulls away with that pale core still tucked inside. The whole plant grows fast and heavy, so a thriving clump fills its space quickly.
Care
The short version: full sun, deep well-drained soil, and about an inch or two of water a week. Cut the old fruited canes out each year and leave the arching new ones plenty of room to spread.
Light
Blackberries color and sweeten best in full sun, six or more hours of it a day striking the canes. A little afternoon shade is tolerated, but the more light the leaves catch, the sweeter and heavier the fruit that follows.
Water
Keep the soil evenly moist but never waterlogged, about 1 to 2 inches of water a week soaking down to the roots. Give more while the flowers open and the green druplets begin to swell, since a dry spell then shrinks the fruit into small, crumbly clusters.
Soil
Set the roots into deep, well-drained loam dark with organic matter. A pH between 5.5 and 7.0 suits them, and free-draining ground keeps the roots and the thick canes clear of disease.
Temperature
The bare winter canes ride out cold to -4°F (-20°C), and the leafy summer growth holds up to heat of 95°F (35°C). That range covers hardiness zones 5 through 9, where the plant stands outdoors unprotected.
Humidity
Open-air humidity of 40% to 70% suits the canes well. Moving air counts for more than the number, since still, damp air trapped among crowded canes is what lets orange rust and dark cane lesions take hold.
Feeding
Feed once in early spring as the dormant canes flush new green growth, using a balanced 10-10-10 or a nitrogen-rich complete fertilizer. That single seasonal feeding usually carries the canes right through fruiting.
Pruning
The canes live on a biennial rhythm, the old and the new standing together. Cut the spent, woody floricanes flat to the ground after harvest, tip-prune the green primocanes in summer to branch them into fruiting laterals, and thin the clump to a handful of strong canes.
Repotting
Blackberries spread their roots in open ground rather than a pot, so repotting rarely comes up. In a container, pot the plant on once roots circle the rootball or the canes stall and the soil dries out fast.
Size & spacing
The arching canes climb 3 to 10 feet (90 cm to 3 m) and reach as wide. Give each plant that much room to arch and sucker, both so air moves between the canes and so the spreading clump keeps off its neighbors.
When to plant
Blackberries go into bare ground while still leafless and dormant. Set bare-root or potted canes out in late winter to early spring once hard frosts have passed, watch the blossom open along the floricanes in late spring, and pick the darkening berries through the heat of July and August.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Set out dormant bare-root or container canes in late winter to early spring after danger of hard frost has passed.
- Harvest: Blooms in late spring; berries ripen mid to late summer (typically July to August).
Hardiness
USDA hardiness zones: 5–9
Temperature: down to -29°C
Troubleshooting
Most blackberry trouble writes itself across the canes or the fruit, where a close look picks it out early: a powdery cast on a leaf, a sunken mark on a stem, a berry that ripens unevenly. Match what you see below, then act before a fungus or a mite settles in for good.
Bright orange powder dusting the underside of the leaves
A bright orange, powdery bloom of spores coating the leaf undersides is orange rust, a fungus that runs through the whole plant beneath the surface. The infection is permanent once the spores show, and the cane lingers as a source for the rest, throwing weak, spindly growth. The fix is to lift the entire plant, roots and all, and keep it well away from the compost.
Fix:
- Dig out and destroy entire infected plants including roots
- Do not compost infected material
Dark, purple-edged sunken marks ringing a cane
Sunken lesions with purple borders that crack and ring right around a cane are cane blight and anthracnose, fungi that lodge in a wound and girdle the stem so everything above wilts and dies. Cut the marked canes out well below the lesion and thin the rest until air slips through the canopy. Make every cut on a dry day, since a fresh wound in wet weather is how the spores work their way in.
Fix:
- Prune out and destroy affected canes below the lesion
- Thin canes to improve air circulation
Lopsided, crumbly berries studded with hard red druplets
A berry that comes off small and lopsided, some druplets swollen and dark while others sit hard and red, is the look of poor pollination, though a redberry mite or a virus leaves the same uneven beads. Draw bees to the flowers with plantings nearby, and treat the canes with horticultural oil where mites are at work. Pull and replace any plant you suspect of carrying a virus.
Fix:
- Encourage pollinator activity near the planting
- Apply horticultural oil to manage mites
Toxicity
Nothing in the plant carries a poison. The dark berries, the green leaves, and the canes are all safe for people, pets, and livestock, and the fruit is a treat for every one of them. The single real hazard is physical, since most blackberries arm their canes with sharp prickles that scratch skin and snag fur.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
No part of the plant holds a poison for a cat. The hooked prickles along the canes are the only thing to watch, since they can rake a curious paw or nose.
Dogs None
A dog can take the dark, ripe berries with no harm, and many seek them out. A large mouthful at once can loosen the stomach, so the helpings stay small.
Horses Safe
Horses crop the leaves and fruit with no ill effect. The prickled canes are the real concern, since the sharp points can cut a soft muzzle.
Rabbits Safe
The leaves and fruit are safe, and rabbits work happily along the foliage. Offer the berries sparingly, since the sugar runs rich for a small animal.
Livestock Safe
Cattle, goats, and sheep browse the bristling brambles freely, and goats will strip a thicket bare. None of it is poisonous to them.
Birds Safe
Birds settle on the ripe black fruit and carry the seeds far and wide. The berries pose no danger to them at all.
People Safe
Blackberries are eaten fresh or cooked, and the young leaves have long been steeped as tea. The thorns are the only thing to mind as the hand reaches in to pick.
The main hazard is physical rather than chemical: most wild and cultivated blackberries bear sharp thorns (prickles) along the canes that can scratch skin or injure pets, though thornless cultivars such as 'Navaho' and 'Apache' exist and are safer to handle.
Varieties
Blackberries run to hundreds of selections, divided by habit into stiff upright canes and long trailing ones. These three are worth knowing, two of them bred with smooth, thornless canes.
Navaho
A thornless, upright type from the University of Arkansas and USDA breeding program, carrying sweet, firm berries on smooth canes a bare hand can grip.
Marionberry
A trailing blackberry from Oregon State University, bred by crossing Chehalem with Olallie, its long lax canes a fixture across the Pacific Northwest.
Apache
Another thornless, upright cultivar, set apart by its unusually large fruit and its strong resistance to disease.
Companions
Blackberries do best kept apart from their own relatives and from the nightshade family, since both trade diseases that brambles are prone to.
Keep apart
Raspberry and other Rubus: Planting close to other brambles spreads shared diseases such as orange rust and viruses.
Tomato, potato, and other Solanaceae: They share susceptibility to Verticillium wilt, so avoid planting blackberries where solanaceous crops recently grew.
How to propagate
Blackberries multiply readily, and a single clump of canes opens several ways to do it. Layering and division ask almost nothing, while cuttings take a little more patience.
LayeringEasy
Late summer · Roots form in 6 to 8 weeks; transplant the following spring
Trailing types layer themselves almost without help, their long canes arching back to the ground. In late summer, bend a cane tip down onto bare soil and pin it, and fresh roots grip within about 6 to 8 weeks. Leave the new plant joined to the parent over winter, then lift it the following spring.
DivisionEasy
Late winter to early spring while dormant · One growing season
An established clump pushes up rooted suckers in a ring around its base. Dig those suckers, or split the crown, in late winter to early spring while the plant is bare and dormant, then replant straight away. Give each division one growing season to root in before it carries a real crop.
Stem cuttingsModerate
Winter for root cuttings or summer for softwood cuttings · Several weeks to a few months
Cuttings ask for a steadier hand than layering or division. Take firm root cuttings in winter or soft, green softwood cuttings in summer, and let rooting run anywhere from several weeks to a few months. Root cuttings are the usual way nurseries build up the upright kinds.
Myths
Blackberries and raspberries are the same fruit since both are brambles.
Both sit in the genus Rubus, so the mix-up is easy, but the picked fruit shows the difference plainly. A blackberry keeps its pale white core, the small plug called the receptacle, lodged inside the cluster of druplets, while a raspberry pulls free and leaves that core on the plant, which is why a raspberry comes off as a hollow cup.
Every blackberry has thorns.
Sharp prickles line the canes of many plants, but they are no longer the rule. Modern cultivars such as Navaho and Apache grow fully thornless, their canes smooth to the touch, and they crop just as well, so the fruit comes in without a scratch.