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Growing your own black raspberries is a great way to get juicy delicious fruit for making jams, smoothies, muffins, preserves, and pies. Below, we’ll go over everything you need to know about how to grow black raspberries, as well as other useful raspberry tidbits.
The black raspberry plant (Rubus occidentalis) belongs to the rose family (Rosaceae), which includes many familiar relatives such as the apple, pear, strawberry, and roses.
The black raspberry is considered a bramble (UK) or caneberry (US), which is any plant belonging to the genus Rubus.
There are hundreds of species of Rubus plants, including familiar relatives such as red raspberries (Rubus idaeus) and blackberries (Rubus fruticosus sp. agg.), which are related but different plants.
Wild black raspberries are native to North America, though other varieties of black raspberries are found all over the world (e.g. Rubus coreanus is known as Korean black raspberry and is native to East Asia).
Black Raspberry Care
There are many cultivars of black raspberry to choose from, though the most commonly available black raspberries are summer-bearing floricanes (second-year canes).
This means they grow non-fruit bearing canes or branches (aka primocanes) in the first year, which go dormant in the winter, before producing fruit-bearing floricanes the following summer.
Black raspberries are relatively easy to maintain and grow, though it may take some dedicated patience (~16-18 months) and pruning to bear fruit.
Soil
Black raspberries prefer deep, well-draining, sandy, loamy soil with lots of organic matter, so mulching and composting are encouraged.
Ideal soil pH is between 5.5 and 6.5. Incorporate phosphorus into the top 8 inches of soil before planting for better growth.
Watering
Black raspberries need about one-inch of water per week during the blooming/fruiting season. Depending on soil type, this means watering the plant at least once or twice a week.
Avoid wetting leaves when watering, as this can invite diseases. Water less in the non-fruiting season, as this can cause chlorosis or yellowing of leaves.
Lighting
Raspberries need full sun, but may benefit from partial afternoon shading in extremely hot climates.
Humidity & Temperature
Raspberries do best in average (40–60%) humidities and ideal summer temperatures between 70-75°F (21-24°C).
Raspberries have a chilling requirement of at least 800 hours of temperatures between 37-50°F (3-10°C) in order for buds to break. Temperatures below -5°F (-21°C) will kill black raspberries. [1]
Avoid windy areas, as exposure to dry winds will dehydrate and kill exposed branches.
Fertilizing
Fertilize raspberries annually in early spring as growth starts and again in June with a balanced 10-10-10 fertilizer (containing equal amounts nitrogen, phosphorus, and potassium).
Use one-half cup fertilizer per plant in the first year and a full cup per plant in the second year.
Mulching and adding compost to the soil every year will also help improve the soil quality.
Propagation
Although possible to propagate from seeds, black raspberries are often grown new via dormant plants (bare roots) bought at nurseries.
Black raspberry bushes do not produce as many suckers as red raspberries, so they are best propagated via “tip layering.”
The tips of new black raspberry branches produced in the summer will naturally bend as it reaches for the ground.
In the summer, take and bury these tips 3-5 in. into a container of potting soil or directly into the ground. Secure tips with a stake and ties to ensure the wind does not uproot the buried tips. Roots will usually take hold in a few weeks or by winter.
Wait until spring to cut the newly rooted plant from the mother (leave about 6-7 inches). This sapling can now be transplanted for new black raspberry plants.
Diseases & Pests
Raspberries are susceptible to a few diseases:
- Cane blight is a common fungal infection which causes purple black cankers to form on young canes. Infected canes will look cracked and brittle (breaking easily) with black specks.
- Gray mold starts as a light brown area on fruits before engulfing the entire berry in gray powder.
- Raspberry leaf spots will infect young leaves, leaving small dark green circular spots, before enlarging to a light tan or gray color.
- Other common diseases include spur blight (which causes brown lesions on stems), yellow rust (which causes yellow-orange spots on leaves), and leaf curl virus (which causes curling yellowing leaves).
- Raspberries are also susceptible to root rot, raspberry ringspot, and raspberry mosaic disease. [2]
To prevent common fungal diseases, plant raspberries in full sun and in areas with good drainage. Avoid overfertilization and prune fruiting canes immediately after harvest.
Affected berries and leaves should be pruned and destroyed. Spray with suitable fungicide to treat.
Raspberries are also susceptible to invasive pests such as spotted wing drosophila and Japanese beetles, which feed on leaves and berries.
Other occasional insects include spider mites, leafhoppers, sap beetles, leafrollers, and weevils. Treat with insecticide or introduce natural predators.
Hardiness zones
Raspberries grow best in USDA plant hardiness zones 4-8, depending on the cultivar.
Pruning
Pruning will help encourage larger berries and more productive yields.
Prune black raspberries in March or early April by removing small, weak canes, leaving only 4-5 of the largest canes per plant. Cut lateral branches down to 12 inches (0.3 m).
In late May, check on the raspberry canes and pinch or cut off 3-4 inches off the top tips of the shoots.
Pruning and pinching tips will encourage lateral shoot development and greater fruit yields the next summer. [3]
A trellis and twine support system will make growth, harvesting, and pruning more manageable. As canes grow, drape them over the trellis system and secure them with ties.
After harvesting in the second summer, be sure to prune off old fruiting canes at the soil surface.
How to grow black raspberries from cuttings
Besides tip layering, black raspberries are also grown via cane (stem) cuttings and via bare roots.
To grow by stem cuttings, find a healthy plant and look for stalks from the upper part of the plant that are green and wood color with at least a few leaf nodes present. Cut with a sharp knife, remove leaves, and then transplant stem to potting soil.
Bare roots are dormant raspberry plants with dormant canes and a healthy root system intact. After obtaining, prune damaged roots, and allow bare roots to soak in a bucket for two hours before planting.
Best black raspberry varieties
Black raspberries come in many cultivars that display different growth habits (erect or free standing vs. trailing or vining) and features (thorny vs. thornless).
Thorny plants make picking difficult as they may prick skin.
Below are some examples of popular black raspberry varieties:
- The “Bristol” variety is a type of erect and thorny black raspberry that grows very flavorful (some say best-tasting), large, glossy, and sweet fruit.
- “Munger” is a thorny semi-erect variety introduced in 1897 and is the leading commercial variety grown in Oregon, which is the commercial center of U.S. production of black raspberries. Munger black raspberries are noted for their small seeds and big flavor.
- “Jewel Black” is a popular variety of trailing thorny black raspberry that produces large and glossy black raspberries that are great for eating, jams, preserves, or pies.
Thornless black raspberries are rare, though a patented thornless variety is available for sale online.
How to grow black raspberries in containers
Make sure containers are of adequate size: at least 36 inches wide and deep. Half barrel or 5-gallon (20 liters) containers are the ideal sizes to ensure enough room for new canes to grow.
Ensure containers have proper drainage holes, as black raspberries are prone to root rot. In large containers, black raspberries can be moved indoors if winter temperatures drop below -5°F (-21°C). Avoid ceramic or terracotta pots, as these can freeze over and crack.
Black Raspberry vs Blackberry
Black raspberries and blackberries (Rubus fruticosus sp. agg.) are actually separate species under the same Rubus genus. The scientific name for blackberries is complicated, as it does not have a distinct species categorization, and is actually made up of many possible aggregate species.
Blackberries can also be distinguished from black raspberries by their receptacles – the white central core of the fruit. When picked, black raspberries lose their receptacles and are hollow inside.
Blackberries are also larger, shinier, and do not have the fine hairs present on the surface of black raspberries. Black raspberries also taste sweeter than the tartier blackberry.
References:
[1] Rose, L. (2020, November 17). What climate do raspberries grow in? Home Guides | SF Gate. Retrieved November 2, 2022, from https://homeguides.sfgate.com/climate- raspberries-grow-in-67027.html.
[2] Author unknown, [nd]. Raspberry | Diseases and Pests, Description, Uses, Propagation. Penn State University Plant Village. Retrieved November 2, 2022, from https://plantvillage.psu.edu/topics/raspberry/infos.
[3] Jauron, R. (2013, January). Pruning Raspberries. Iowa State University Extension Master Gardener Program. Retrieved November 2, 2022, from https://store.extension.iastate.edu/product/5733.