Caren White is a Master Gardener and instructor at Home Gardeners School. She has been associated with Rutgers Gardens for over a decade.
Berries are one of the delights of the summer. Growing native blackberries is easy and rewarding. Beware though. Birds and animals also like them so you will either have to share your harvest or cover your shrubs with netting to keep them out.
What are Blackberries?
Blackberries (Rubus fruticosus) are a perennial shrub that bears fruit as berries. There are species that are native in Europe as well as North America. The berry bushes that we grow in our yards are all cultivars of North American blackberry species.
Blackberries are related to roses and have thorny canes like roses. A big difference between them is that while blackberry roots are perennial, their canes are biennial i.e. they only live for two years. Like other biennial plants, the canes grow vegetatively, meaning they only develop foliage, the first year. The second year, the canes flower and bear fruit, then they die. The roots, which are perennial, replace the canes the following year.
There are two types of blackberry shrubs: upright and trailing. The upright shrubs have canes which grow upwards. They don’t need support. The trailing shrubs are closest to native blackberries which are all trailing. The trailing ones definitely need a trellis to lift the canes off of the ground and prevent tangling. If the canes are allowed to tangle, they develop into an impenetrable bramble which makes it difficult to prune and harvest.
To make matters even more confusing, newer cultivars have been developed that bear fruit the first year instead of the second. These are known as primocane blackberries. The term “primocane” refers to the canes that grow vegetatively the first year. The newer cultivars bear fruit during their first year of growth on their primocanes. Blackberries originally only bore fruit on their floricanes which are second year canes. Primocane blackberries bloom and bear fruit in the fall. Floricane blackberries bloom and bear fruit during the summer.
How to Grow Blackberries
Thankfully, no matter which kind of blackberry you want to grow, they are all treated the same. Choose a sunny spot in your yard. Blackberries do not grow and bear well in partial shade. They require 6 to 8 hours of sunlight each day. Wild blackberries grow in any type of soil. Modern cultivars prefer rich loamy well-drained soil that is slightly acidic, pH 5-5 - pH 7.0.
Plant your shrubs in the early spring when they are dormant. They can be planted in the late fall before the ground freezes. They are not dormant yet so they have time to establish their root systems. Most nurseries only sell berry bushes in the early spring while they are dormant so you may not have much choice when to plant.
Upright shrubs can be planted fairly close together, about 3 feet apart. Trailing shrubs need more space and should be planted 5 to 8 feet apart. If you don’t have space enough for more than one shrub, you only need to plant one. Blackberries are self-fertile which means that they don’t need to be pollinated by another shrub to produce fruit.
Blackberries need moisture. Make sure that your shrubs get at least 1 inch of water every week. A good thick layer of mulch will help the soil around your shrubs to stay moist. Fertilize with a balanced fertilizer such as 10-10-10 in the spring when your shrubs are breaking dormancy.
Keep an eye on your shrubs. Blackberries grow by runners. Be sure to remove any suckers which are new plants which are growing from the underground runners. Suckers are called that because the “suck” food and water from the parent plant via the runners. Removing them means that food and water will remain to nourish your existing shrub.
How to Grow Blackberries in a Container
Thanks to the miracle of plant breeding, there are now dwarf blackberry bushes available that can also be grown in containers if you only have a deck, patio or balcony on which to grow your plants. The most popular cultivar is Babycakes which is 3 – 4 feet tall and 3 – 4 feet around. It should be grown in a 5 gallon container in a sunny spot that gets 6 to 8 hours of sunlight every day. You will need to water your container more often because it will dry out quicker than plants planted in the ground. A thick layer of mulch will help keep the soil moist. Fertilize with a balanced fertilizer such as 10-10-10 in the early spring as the shrub is breaking dormancy. Dwarf blackberry bushes do not need to be pruned.
How to Prune Blackberries
How you prune your blackberries depends on which kind you are growing.
It is recommended that you prune the floricanes to the ground after they have finished fruiting. However, I like to wait until after they have begun to die to start pruning. This allows the canes time to photosynthesize (make food from the sun) and send that food to the roots to help them survive the winter and grow next year. The more food the roots have, the stronger they will be. The primocanes (first year canes) do not need to be pruned.
Prune the dead floricanes during the winter when the plant is dormant. Unlike the trailing shrubs, you should prune the primocanes (first year canes) during the summer. Prune the top 2 inches off of any canes that have reached 4 feet tall. This will encourage the canes to branch and produce more berries next year.
How to Harvest Blackberries
The window to harvest your blackberries is very short. The berries start out green, then as they ripen they turn red and then glossy black and finally dull black. Harvest only the dull black, fully ripe berries. They will not continue to ripen after they have been picked. The time between glossy black and dull black is only 2 – 3 days so you will need to check your fruit every day.
Harvest early in the day and refrigerate your berries immediately after you have picked them.
How to Store Blackberries
Blackberries are highly perishable. They can only be refrigerated for a few days. It is best to either eat them immediately or can them or preserve them as jams or freeze them. You can also use them to make delicious pastries which can be either eaten immediately or frozen.
How to Propagate Blackberries Using Stem Cuttings
Blackberries are very easy to propagate using stem cuttings because they sucker so easily. You can make a cutting from one of the primocanes in the spring when they are growing and literally just stick it in the ground wherever you want a new blackberry bush to grow. Keep the soil moist. Roots should begin to form in 2 – 4 weeks. You will know that roots are growing because your cutting will start growing new leaves. Plants that don’t have roots can’t grow new foliage.
© 2019 Caren White
Caren White (author) on May 29, 2020:
You don't need to propagate any of the "runners" unless you want blackberries in a different part of your yard or want to share with friends.
For information on watering, please see my article: https://dengarden.com/gardening/How-to-Water-Your-...
Demas W Jasper from Today's America and The World Beyond on May 28, 2020:
A great and very useful presentation. We started with the purchase of six Navajo Thornless and now from those six we have close to 60 plants. Our soil is mostly old orchard, clay soil. Some plants I water by two gallon watering cans. How many of those will provide your recommended 1" water per week? How do I decide which "runners" to propagate. as I had thought they were all good, new plants?