Gadenin日本語Get the appThe principle behind every cut
A blackberry cane lives two years. In its first year it grows from the crown and does nothing else. In its second year it flowers, fruits and then dies. It will never fruit again, and it will never recover; a cane that has carried berries is finished the moment the last one comes off. That single fact drives all blackberry pruning.
So there is nothing to judge about vigor, shape or bud direction. You are only answering one question about each cane: has this one fruited? If yes, cut it out at ground level. If no, keep it and tie it in. Every complication in blackberry pruning comes from not being able to tell those two apart, which is a problem you solve in summer, not with the pruners in your hand in winter.
Make the winter cut obvious by training in summer
Train this year's new canes to one side of the crown and last year's fruiting canes to the other, from the moment the new canes are long enough to bend. By the time you come to prune, the two ages are on opposite halves of the wires and the decision is made by position, not by inspection. Cut out the whole of the fruiting side, then move the new side across to take its place.
If a plant has never been trained this way and everything is tangled together, you can still tell the ages apart, but you have to look closely. A cane that has fruited carries dried, brown remains of the fruiting side shoots along its length, and its bark is duller, browner and often peeling slightly. This year's cane is smoother, greener or red-tinged, and has no side shoot scars. Work along the plant one cane at a time, trace each from the base, and tag the ones you intend to keep with a loop of soft string before you cut anything.
| Cane | Bark and appearance | Decision |
|---|---|---|
| Has fruited | Dull brown, slightly peeling, dried fruiting side shoots | Cut to ground level, no stub |
| Has not fruited | Smooth, green or red-tinged, no side shoot remains | Keep, tie in, shorten only the tip |
| Thin or whippy new cane | Pencil-thin or thinner at the base | Cut out; it will not carry a crop |
| Damaged or diseased cane | Dark sunken patch or purple blotch near the base | Cut out even if it has not fruited |
| Cane from outside the row | Emerging in the path or lawn away from the crown | Pull it out rather than cutting |
When to cut
The fruited canes can come out any time from the end of picking through to late winter. Cutting them out as soon as the last berry is picked is better: it opens the plant up immediately, gets air around the new canes while they are still ripening their wood, and leaves you less dead material to work through in cold weather. There is no benefit to leaving spent canes standing.
Leave the tipping of the new canes until the end of winter, when the worst frosts are behind you. Cane tips are the least hardy part of the plant and often die back a few inches over winter, so shortening them early just means cutting twice.
- Cut the fruited canes out at ground level Take them right down to the soil, leaving no stub. A stub dies back and becomes an entry point for cane blight, and it is a nuisance to kneel on later. Use loppers on anything thicker than a pencil rather than forcing pruners, which crushes the cane.
- Pull the cut canes clear and remove them Drag the cut canes out through the wires and away from the row. Do not leave them lying under the plant: dead cane on the ground harbors the same fungal diseases that attack living canes, and thorny debris in a bed you have to kneel in causes trouble all year.
- Select four to six canes and tie them in Keep the thickest canes that arise closest to the crown, spaced 4 to 6 inches (10 to 15 cm) apart along the wires. Tie with soft string in a figure of eight so the tie does not chafe. Cut out every surplus cane at ground level, including any that look perfectly healthy; a crowded plant fruits worse than a thinned one.
- Tip the retained canes at the end of winter Shorten each retained cane by about 6 inches (15 cm), or back to the top wire if it overshoots, cutting into firm live wood below any winter dieback. This encourages the fruiting side shoots that carry the actual crop and stops the tips reaching the ground and rooting.
Mistakes that cost you a crop
The commonest error is cutting the whole plant to the ground in winter, the way autumn raspberries are treated. Do that to a blackberry and you remove every cane that would have fruited, so you get a vigorous leafy year with no berries at all. The plant is not damaged and it will crop the year after, but you have lost a season.
The second commonest is not pruning at all. An unpruned blackberry keeps its dead canes standing among the live ones, gets denser every year, holds humid air, ripens fruit you cannot reach and eventually crops only on the outer shell. Restoring one is a matter of cutting everything dead out in one winter, keeping four or five live canes, and starting the two-sided training the following summer.
Record which side of the plant carries the fruiting canes each year in your notes. After swapping sides annually for a few seasons it is easy to lose track, and the note takes five seconds against half an hour of tracing canes.