Blackberries can in principle also be grown from the seeds of the fruit if they are stratified and sown with a lot of patience. However, due to the long duration, this propagation method has almost no significance for blackberries.
How do I grow blackberries from cuttings?
To grow blackberries from cuttings, cut a harvested vine into pieces with three to four leaf nodes each in August or September. Remove all but the top pair of leaves and insert the bottom of the cuttings about two buds deep into loose soil.
What you need to know about propagation from cuttings
Cutting and rooting cuttings is a vegetative propagation method, so that all plants grown are true to the variety and genetically similar to the mother plant. When propagating blackberries, the technique of propagation from cuttings should also be favored, as it saves time in terms of the cultivation period until the first harvest. If you would like to grow new blackberry plants yourself from cuttings, you should ideally cut the corresponding cuttings in August or September.
Cut cuttings to the correct length
You can cut a harvested blackberry vine into pieces with sharp planting scissors in late summer for propagation from cuttings (€31.00 on Amazon). This is particularly practical because blackberries are always cut back to fruit on two-year-old tendrils and harvested tendrils are cut back close to the ground anyway. The cuttings should be cut so that they each have three to four leaf nodes. Apart from the upper pair of leaves, all others are stripped off, then you should insert the cuttings with the lower end about two leaf buds deep into loose soil for rooting.
Promote rooting with moisture and warmth
First you can put several cuttings in a pot and place it in a warm place in the greenhouse or on the balcony. When caring for these cuttings, you should pay attention to protecting them from frosty temperatures and ensuring adequate watering. If optimal conditions prevail, blackberry cuttings can develop roots within about four weeks. In the spring you can then transplant the overwintered cuttings into an individual pot. With good care, the offshoots will be strong enough by autumn to be planted in their final location outdoors.
Tips & Tricks
A larger number of plants are required, especially for a trellis or hedge made of blackberry plants. You can produce these yourself inexpensively by propagating them using cuttings so that you can then plant the plants at their destination the following year.