“Thornberry” isn’t a scientific plant name. In gardens it nearly always means a blackberry, the prickly bramble whose canes bear dark, juicy fruit. The name is a little misleading, because many of the best garden blackberries today are bred to have no thorns at all.1OSU Extension Service. Blackberry Cultivars for Oregon So what you’re really choosing is a type of blackberry, and that choice shapes how much space, support, and pruning the plant will need. Once it’s settled in, a blackberry is among the more forgiving fruits, with most of the real work coming down to a yearly cut-back and careful picking.
The Blackberry Types Sold Under This Name
Every blackberry works on a two-year cane cycle. In its first year, a cane is leafy and grows but usually doesn’t fruit (growers call these primocanes).2OSU Extension Service. Blackberry Cultivars for Oregon In its second year it flowers and bears berries (a floricane).3OSU Extension Service. Blackberry Cultivars for Oregon A plant therefore always carries this year’s new growth right beside last year’s fruiting canes.
Trailing blackberries send canes along the ground that can reach 20 feet long.4OSU Extension Service. Blackberry Cultivars for Oregon Their new canes come only from the base of the plant, not the roots, so they spread less than other blackberries.5OSU Extension Service. Blackberry Cultivars for Oregon The berries are long, with small seeds and an intense, aromatic flavor.6OSU Extension Service. Blackberry Cultivars for Oregon All that sprawling growth needs a trellis.7OSU Extension Service. Blackberry Cultivars for Oregon
Erect blackberries grow stiff upright canes up to about 12 feet if left unpruned.8OSU Extension Service. Blackberry Cultivars for Oregon They send up suckers from the roots and can colonize an area, forming a hedgerow.9OSU Extension Service. Blackberry Cultivars for Oregon Their berries have larger seeds and milder flavor than trailing types.10OSU Extension Service. Blackberry Cultivars for Oregon Semierect blackberries are typically thornless, with thick canes up to 20 feet that arch to the ground if unpruned.11OSU Extension Service. Blackberry Cultivars for Oregon They rarely sucker from roots and generally yield more fruit than the other types.12OSU Extension Service. Blackberry Cultivars for Oregon
If you’re not sure what you bought, check the tag for words like trailing, erect, or semierect, or a variety name you can look up. After a season, stiff upright canes suggest an erect type, while long, flexible canes lying on the ground suggest a trailing one. New shoots popping up a few feet from the plant are one clue to an erect, root-suckering type, though the tag or variety name is more reliable. Thornless canes make pruning, tying, and picking far less painful, which makes them a better pick near paths, play areas, or anywhere children harvest.
In a small yard, skip erect types that sucker into lawns and beds. Trailing types suit a fence or wire trellis along a property line. Semierect types suit gardeners who want the biggest harvest and have room for long arching canes.
Climate and Soil a Thornberry Needs
Fruit plants count winter cold in chill hours, usually the hours spent between 32°F and 45°F.13Food Forest Nursery. Chill Hours By ZIP Code Map | Fruit Tree Chill Hours When a plant gets enough winter cold, its buds are ready to grow as spring warms.14Food Forest Nursery. Chill Hours By ZIP Code Map | Fruit Tree Chill Hours Too little can bring late leaf-out, scattered bloom, poor fruit set, and lower-quality fruit.15Food Forest Nursery. Chill Hours By ZIP Code Map | Fruit Tree Chill Hours Chill needs are separate from hardiness, which is whether winter lows will kill the plant, and you need to match both.16Food Forest Nursery. Chill Hours By ZIP Code Map | Fruit Tree Chill Hours
Before buying, look up your area’s typical winter cold and your USDA hardiness zone, then compare both to the variety’s label or the nursery’s description. Gardeners in mild-winter areas should pick varieties described as low-chill. Patchy, drawn-out bloom after a mild winter can hint at too little winter cold, though other stresses can cause it too. Canes killed back in a hard freeze hint that the variety isn’t hardy enough for you. Either sign means a different variety may suit your site better.
Most crops grow best in soil with a pH of 6 to 7.5.17USDA-NRCS. Soil Health — Soil pH Soil that is too acidic or too alkaline leaves plants short of many nutrients and lowers yields.18USDA-NRCS. Soil Health — Soil pH Clay and soils rich in organic matter resist pH change more than sandy soils.19USDA-NRCS. Soil Health — Soil pH So sandy soils respond faster to lime or sulfur, while clay may take more amendment and more time.
A home kit or an extension office soil test gives you your pH before planting. Lime raises pH in acidic soil, and sulfur lowers it in alkaline soil. Adjust the season before planting, since changes take months. Choose a sunny, well-drained spot, because soggy roots invite rot.
Pruning and Training the Canes
Second-year canes are finished once they fruit, so cut them to the ground right after harvest.20University of Maryland Extension. Orange Rust is a bigger problem than usual this year in brambles Removing them and thinning crowded canes lets air move through the plant, which helps the leaves dry and limits disease.21Weekly Crop Update. What Is a Thornberry Plant? Growing and Care Tips
Two posts with one or two wires about 3 and 5 feet high suit most home plants. Fan or weave trailing canes along the wires and tie them loosely. Keep this year’s new canes on one side and fruiting canes on the other.
Tipping new canes multiplies fruit. On primocane-fruiting blackberries, which fruit on first-year canes, snipping the top 2 to 5 cm (about 1 to 2 inches) off canes at about 1 meter (roughly 3 feet) made them grow two to three times more side branches.22Horticulture. Primocane-fruiting Blackberries: The Effect of Summer-Pruning, Tipping, and Chilling on Primocane Morphology, Fruiting Season, and Yield Tipped canes carried almost twice as many flowers.23Horticulture. Primocane-fruiting Blackberries: The Effect of Summer-Pruning, Tipping, and Chilling on Primocane Morphology, Fruiting Season, and Yield Canes tipped twice gave nearly twice the fruit of canes tipped once, and larger berries.24Horticulture. Primocane-fruiting Blackberries: The Effect of Summer-Pruning, Tipping, and Chilling on Primocane Morphology, Fruiting Season, and Yield But cutting canes back again later, or removing the tip just after bloom, lowered the harvest.25Horticulture. Primocane-fruiting Blackberries: The Effect of Summer-Pruning, Tipping, and Chilling on Primocane Morphology, Fruiting Season, and Yield
Flower buds for next year form in autumn and keep developing slowly into winter.26Journal of the American Society for Horticultural Science. Patterns of Floral Bud Development in Canes of Erect and Trailing Blackberries The buds along the middle of a cane tend to be the most developed.27Journal of the American Society for Horticultural Science. Patterns of Floral Bud Development in Canes of Erect and Trailing Blackberries So avoid cutting next year’s fruiting canes short in winter, which removes many of the best buds.
The year runs in a simple order. In summer, soft-tip new canes once they reach about 3 feet. Right after harvest, cut fruited canes at ground level. In late winter, thin to the strongest few canes per plant and remove dead or broken ones. With erect types, also pull or cut root suckers that come up outside the row.
A common mistake is cutting the new green canes because they look overgrown. When in doubt, a fruited cane is woody and brownish, while a new cane is green and leafy.
Fertilizing Without Overdoing It
In a three-year trial on a thornless blackberry, plants given no nitrogen produced as much fruit as plants given moderate or heavy doses.28HortScience. Effect of N Fertilization on `Arapaho’ Thornless Blackberry Berry size and the number of new canes didn’t change either.29HortScience. Effect of N Fertilization on `Arapaho’ Thornless Blackberry
Leaf nutrient levels change through the season differently in trailing types than in later-fruiting erect and semierect types,30HortScience. Seasonal Variation in Mineral Nutrient Concentration of Primocane and Floricane Leaves in Trailing, Erect, and Semierect Blackberry Cultivars so one fixed feeding schedule doesn’t suit every blackberry. Get the soil pH right first, since that decides how well roots can take up what’s already there.31USDA-NRCS. Soil Health — Soil pH
A sensible routine is modest. Work compost into the bed before planting, give a light balanced fertilizer in early spring as growth starts, and mulch to keep roots moist and feed the soil as it breaks down. Pale leaves despite feeding can point to a pH problem rather than a lack of fertilizer, so a soil test is worth doing before adding more. Overfed plants make very tall, soft, leafy canes with few flowers, and the lush growth stays wet and crowded, which invites disease.
Diseases and Pests to Watch For
Orange rust shows up a few weeks after spring growth begins, as orange, blister-like masses on the undersides of leaves.32University of Maryland Extension. Orange Rust is a bigger problem than usual this year in brambles The fungus spreads through the whole plant, so an infected plant can’t be cured.33University of Maryland Extension. Orange Rust is a bigger problem than usual this year in brambles Dig out infected plants, roots included, as soon as you see them and before the blisters release spores.34University of Maryland Extension. Orange Rust is a bigger problem than usual this year in brambles Remove any new suckers that come up from root pieces left behind.35Weekly Crop Update. What Is a Thornberry Plant? Growing and Care Tips
Infection needs more than 12 wet hours in a day at 43°F to 72°F, and fails in heat around 85°F or very dry weather.36University of Maryland Extension. Orange Rust is a bigger problem than usual this year in brambles Fungicides such as myclobutanil or propiconazole can’t cure infected plants; applied every 10 to 14 days when blisters first appear, they only help protect healthy neighbors.37University of Maryland Extension. Orange Rust is a bigger problem than usual this year in brambles
To prevent rust, buy certified disease-free plants from a reputable nursery. Clear wild brambles nearby, where the orange blisters are often easy to see. Mark the spot where you removed a sick plant and watch it for sprouts.
In spring, turn over leaves on new shoots each week and look for bright orange powder or blisters underneath. After rain, check berries for soft spots or gray fuzz. Act the same day, since rust spores spread on wind.
That gray fuzz is gray mold, which rots caneberry fruit, especially in wet weather and heavy dew.38University of Massachusetts Amherst. What Is a Thornberry Plant? Growing and Care Tips Narrow rows, thinned canes, regular picking, and removing rotten berries keep it in check.39University of Massachusetts Amherst. What Is a Thornberry Plant? Growing and Care Tips
Spotted-wing drosophila is a fly about 1/16 to 1/8 inch long with red eyes.40UC Statewide IPM Program. Spotted-Wing Drosophila / Home and Landscape / UC Statewide IPM Program (UC IPM) The males are easiest to spot by a black dot near the tip of each wing.41UC Statewide IPM Program. Spotted-Wing Drosophila / Home and Landscape / UC Statewide IPM Program (UC IPM) Frequent, complete picking leaves fewer ripe berries for the flies.
Their damage shows as berries that soften and collapse sooner than expected. Small pinholes or tiny larvae may appear when you crush a berry. Dispose of damaged fruit in sealed bags rather than leaving it on the ground.
Picking and Storing the Berries
Blackberries get their sugar straight from the plant and won’t ripen or change color once picked.42Blackberry and Raspberry Information Portal. Postharvest Handling and Storage of Blackberries and Raspberies Pick only when the berry is fully black, never half ripe.43Blackberry and Raspberry Information Portal. Postharvest Handling and Storage of Blackberries and Raspberies Avoid picking berries wet with dew or rain, and don’t wash them until you’re ready to eat.44Blackberry and Raspberry Information Portal. Postharvest Handling and Storage of Blackberries and Raspberies
Fully ripe berries often lose some of their glossy shine and turn a duller black, and they pull free with a gentle tug. Shiny black berries that resist are often still tart.
Without a protective skin, blackberries lose water fast and spoil quickly.45Blackberry and Raspberry Information Portal. Postharvest Handling and Storage of Blackberries and Raspberies Each hour of delay before cooling costs about a day of shelf life.46Blackberry and Raspberry Information Portal. Postharvest Handling and Storage of Blackberries and Raspberies So chill them near 32°F in humid conditions to slow drying and decay.47UGA Cooperative Extension. Blackberry Harvesting and Postharvest Handling Keep berries in shallow containers, no more than three berries deep, and handle them gently.48University of Massachusetts Amherst. What Is a Thornberry Plant? Growing and Care Tips
Once the fruit is ripening, pick every two or three days in the morning after the dew dries. Carry a shallow tray rather than a deep bowl, and put berries straight into the fridge, unwashed, in a single layer. Freeze extras spread on a tray before bagging them.
Making New Plants by Tip Layering
Bend a long cane down, bury its tip in soil, and roots will form there over time.49Hipster Homesteaders. 3 Ways to Propagate Berry Vines, Bushes, and Plants (for Free) Once rooted, the tip can be cut from the parent and moved as a new plant.50Hipster Homesteaders. 3 Ways to Propagate Berry Vines, Bushes, and Plants (for Free) This works with a high success rate.51Hipster Homesteaders. 3 Ways to Propagate Berry Vines, Bushes, and Plants (for Free) Unlike stem cuttings, which need ongoing care and succeed only moderately often, tip layering takes almost no attention.52Food Garden Life. Propagate Blackberries by Tip Layering53Hipster Homesteaders. 3 Ways to Propagate Berry Vines, Bushes, and Plants (for Free)
In late summer, choose a healthy new cane whose tip is starting to droop. Dig a small hole a few inches deep beside the plant and bury the tip. Pin it down with a stone or wire staple and keep the spot moist. Check for roots in a few weeks, then cut and replant in fall or spring. Trailing canes that touch soil may root on their own, so lift stray tips you don’t want before they anchor.