Blackberries are evergreen plants with roots that last for years, but the stems of the plant, formally called bushes, are biennial and therefore, before growing again, last for two years. When pruning blackberries, you will need to start treating first year bushes. During the summer, it is best to perform a light pruning and wait for the autumn to perform a complete one.
Steps
Part 1 of 3: Initial Pruning
Step 1. Partially prune the stem
When planting blackberries, prune about two-thirds to three-quarters of the stem, leaving only the crown of the top. This way, you will stimulate the growth of the buds where you made the cut and they will grow more vigorously.
- The "crown" of the cut refers to the part of the cut that is seen in the ground after it has been planted.
- Cutting almost the entire stem reduces the chances of the stem being damaged or getting parasites or other diseases.
- Do this pruning after you plant the cutting in the ground.
- If you plant a seedling, bush, or climbing plant with strong branches, do not prune them again.
Step 2. During the first winter, cut the branches
Growth is usually poor in the first year, so during the first winter you should cut the branches when they reach a height of between 7 and 10 cm. In this way the branches will be more robust and will be able to bear more fruit.
If you are satisfied with the first year of growth, pruning the branches completely is not necessary. Blackberries that grow well during the first year can be pruned according to normal annual procedures
Part 2 of 3: Annual Summer Pruning
Step 1. After harvest, remove the stems that have grown during the first year
As you remove one, you will need to remove the entire branch by cutting it at the base, near the main stem of the plant.
- These stems are the second year branches, responsible for producing most of the plant's fruit. After they produce the fruit they die, that's why they should be removed.
- Remove only the branches that have produced fruit in the first year. You should be able to see stems even after the blackberries have been harvested.
Step 2. Check out the first year branches
When each branch has reached the desired height of about 10 cm, shorten it.
- Usually these branches are born with green shoots that mature during the autumn, turning brown.
- The sturdy branches of blackberries should be shortened and be 120 to 150 cm high from the ground. Instead, the semi-sturdy ones should measure 10 to 15 cm.
- When a branch stiffens, it will be able to better support the weight of fruit and leaves, making it difficult to break.
- This will encourage the growth of buds and side branches. The lateral branches are the ones that produce the fruit. Consequently, the plant will bear more fruit if it has many side branches.
Step 3. Create space
Periodically you should remove the excess branches. In this way the plant will have more light, the air will circulate more easily and the blackberries will grow better without diseases or parasites.
- If there are multiple plants in the same row, keep them 45 to 60cm thick at the base. Trim the low branches when you see them starting to overlap.
- When harvesting second year fruit and cutting branches, remove weak first year branches as well. During growth, first year branches are considered weak if they have few leaves, if they look damaged, or if they have symptoms of disease.
Step 4. Sprout root suckers
If you want, you can grow the root suckers in rows of 30 cm wide.
Root suckers grow and sprout on the crown of the plant. They are not so practical as they do not produce fruit, and when they become too long they absorb the energy needed by the rest of the plant
Part 3 of 3: Annual Winter / Spring Pruning
Step 1. Wait until the end of winter
Full pruning should be done when the plants are dormant and just before they become active again and start growing.
- The best seasons are late winter or early spring. Harsh winters damage the branch tips and side branches. In fact, you should wait until the end of winter and take care of the damaged spots when you also take care of the harvest.
- By doing most of the pruning during the winter you decrease the possibility of damage and diseases such as the deterioration of the branches.
Step 2. Prune all the branches of the first season
Shorten all the branches of the first year plant by about one third of the height.
By shortening the branches, you facilitate the growth of lateral buds in the lower part of these branches that will bloom in spring. The plant will use less energy to sprout outside and will have more energy to produce fruit
Step 3. Thin the lower branches
To make blackberry plants more robust, thin out first-year branches born from the roots of buds and crowns. Leave only a row of 6 or 8 branches every 30cm.
If you are dealing with a blackberry plant that does not produce buds from the root but only from the crown, remove the weak branches with a diameter that measures less than 1.2 cm. Then thin out the new branches from the first year and leave only five or six per row
Step 4. Cut the side branches
Most of the side branches should be trimmed and carried to a length ranging from 30 to 45 cm. By cutting these branches, the fruits will tend to grow larger, as you are essentially forcing the plant to use energy in a more concentrated space.
- Leave the side twigs a little longer in the vigorous branches and make those in the shorter branches shorter.
- If you notice that there are damage caused by winter in the side branches, cut them as much as necessary to eliminate the signs of damage. Do this even if the branch will be shorter than usual.
- Completely remove the lower side twigs (45 cm) in the vigorous branches and those of the weaker branches (30 cm). Air circulation will improve by minimizing the risk of disease and reaping the benefits will be easier.
Step 5. Remove damaged and dead branches
Weak and damaged branches that have not yet been removed should be pruned at this point.
- Weak branches also include those with a diameter of less than 1.2 cm at the base.
- Branches that rub against each other should also be removed.
- Damaged, diseased or dead branches should be cut, to prevent the spread of any insects or pests.
Warnings
- Throw away the second-year branches and the weak, damaged ones you remove from the blackberry plant. In fact, if you leave the wood near the plant, it could attract pests and diseases.
- Make sure the pruning tools you use are clean, especially if they have come into contact with infected or contaminated wood.
