Raspberry and blackberry canes are biennial
Raspberry and blackberry canes are biennial. A cane grows its first year (a primocane), fruits its second year (a floricane), then dies. On summer-bearing types, after harvest cut out only the spent floricanes, at ground level, and keep the current year's primocanes, because they are next year's crop. Cutting every cane down on a summer-bearing plant removes next year's fruit. Ever-bearing (primocane-fruiting) types fruit on first-year canes and, grown for a single fall crop, can instead be cut wholesale close to the ground in winter.
Promising A person has checked it against its sources. If you skip this, it still grows, just less well. The planner suggests it.
How it works
Each cane lives two years while the crown persists. A vegetative primocane in year one becomes the fruiting floricane in year two, and a floricane dies after fruiting, and it will not fruit again or survive another winter. Next year's fruiting wood is therefore this year's primocanes, so removing them removes the crop. The spent floricanes are cut at ground level because dead stubs left standing can harbor canker-causing fungi.
What to do about it
After harvest, or while the plants are dormant, cut the canes that fruited out at ground level and leave the current primocanes standing; thin crowded primocanes so the keepers grow stout. On an ever-bearing type grown for one fall crop, cut all canes very close to the ground in winter instead.
How much it matters: No figure is stated. Keeping the primocanes preserves next year's crop outright; removing the dead floricanes flush with the ground also removes overwintering cane-disease harbor. Because which canes to cut is the gardener's annual choice, the rule only advises.
The evidence
Evidence: checked against 2 sources in the research-based literature.
The 2 sources
In the second growing year, those one-year-old canes, now called floricanes, produce flowers and fruit on main stems and laterals (side branches)
Plants it applies to
How this rule has changed
Every change is dated, newest first. The full record, with each reason, is in the data download.
- Wording made clearer
- Added to the rules
Cite this page
Milpa Gardens. "Raspberry and blackberry canes are biennial. A cane grows its first year (a primocane), fruits its second year (a floricane), then dies. On summer-bearing types, after harvest cut out only the spent floricanes, at ground level, and keep the current year's primocanes, because they are next year's crop. Cutting every cane down on a summer-bearing plant removes next year's fruit. Ever-bearing (primocane-fruiting) types fruit on first-year canes and, grown for a single fall crop, can instead be cut wholesale close to the ground in winter." Evidence grade: Promising. https://milpa.garden/rules/raspberry-blackberry-canes-biennial-cane-grows-first/
A garden planner built on graded evidence. Every claim states its evidence grade and links its sources on the page. Cite it with the grade, and add the date you read it.
Report a problem with this claim
How we grade evidence
- Well established
- The rule names its mechanism and is settled, by sources a person has read and checked or by plain arithmetic and geometry.
- Promising
- The mechanism is named and the literature backs it. A few questions are still open.
- A good hunch
- Plausible by its mechanism, but field studies are thin, so treat it as a lean.
- Contested
- The evidence points both ways, or no study has tested it, so the planner does not enforce it.
- Refuted
- The claim did not survive its sources. It is kept so the folklore can be answered.