Prune repeat-flowering roses in spring, as soon as the forsythia is in yellow bloom. Its flowering shows that long spells of frost are no longer likely where you live, depending on the location roughly between mid-March and mid-April. Once-flowering roses, by contrast, are pruned only after they have flowered in summer.
Why a signal beats a date
A calendar date applies to Basel just as much as to a mountain village, even though spring arrives weeks later up there. Forsythia responds to the actual weather where it grows. If it is flowering in your neighbourhood, your rose has put the winter behind it too. A short cold snap can still happen, so it is worth checking the forecast for the next few days before you prune.
Which roses do I prune when?
- Repeat-flowering bedding and hybrid tea roses: at forsythia time, cut back hard to three to five buds.
- Repeat-flowering shrub roses: at forsythia time, thin lightly and shorten by about a third.
- Once-flowering roses and ramblers: do not prune in spring, because they flower on last year’s wood. Prune them in summer after flowering.
How do I make the cut correctly?
Cut about 5 millimetres above an outward-facing bud, sloping slightly away from the bud so rainwater runs off. That way the rose grows open and outwards rather than inwards. First remove dead, diseased, very thin and crossing stems. Sharp, clean secateurs avoid crushed cuts through which diseases can get in.
What happens if I prune too early?
Pruning in February during mild weather encourages the rose to start growing. If a frosty night follows, the young shoots freeze and you have to prune a second time. That costs the plant energy and delays flowering.
The example of the young rose by the house wall on the home page also shows how much location and weather can shift a care task.