Pruning is undertaken to encourage new growth by removing old and spindly growth.
This increases light and air circulation into the plant, helping improve flower production and maintain the shape of the plant.
When to prune
Modern roses are usually repeat-flowering, meaning that they produce blooms throughout the late spring, summer and into autumn.
They should be pruned at their most dormant stage, when the heaviest of frosts have passed.
Depending on the microclimate of your garden, this is usually July or August in Dunedin.
How to prune
1 Remove the three Ds: dead, diseased and damaged canes, cutting them neatly and cleanly at the base of the bush or at a suitable outward facing bud.
2 Open up the centre of the rose bush, removing any crossing branches and inward growth as well as all side shoots.
3 Select five to seven healthy canes to retain; they should be evenly spaced around the base. Shorten by a half to one third to an outward-facing bud. (This can be anything from two to six buds from the base of the canes).
4 The graft union of roses can be carefully scrubbed with a wire brush to remove any moss and old bark. This stimulates desirable new growth from the base.
5 Clean up old leaves from around the base as they may carry fungal diseases.
6 If possible, when pruning is finished, spray with copper and winter oil to help wounds heal and to help prevent fungal diseases.
All cuts should be made sloping away from the direction of growth, about half a centimetre above the bud.
This ensures that any moisture runs away from the bud, reducing the chance of rot and disease.
Always use clean, sharp secateurs.
- Linda Hellyer is curator of the rose garden at Dunedin Botanic Garden.
