Life & Style
It's rose-pruning time, so grab your secateurs and brave the cold weather to tackle your roses. It's not essential to prune roses – they will still survive – but most rose fanatics recommend it.
When pruned, roses produce more and better blooms the next season.
In most parts of New Zealand, rose pruning is carried out between July and mid-August, although in the north, gardeners often start earlier, and in the south a little later.
If in doubt, your local rose society is a great source of information for when to start pruning in your area.
If you prune too early, your roses will come away into new growth, only to be knocked back by the cold weather later on in winter.
Ideally, you should prune on a fine day, when there is little or no wind, to help reduce the chance of silverleaf infection. In fact, any large canes are actually best removed in autumn (April), because the silverleaf spores aren't around then.
It's a little late now, but remember that for next year.
Winter cleanup sprays are recommended for dealing with spores from fungal diseases (rust, blackspot, powdery mildew, etc), but while it was previously recommended to spray plants with lime sulphur before and after pruning, that's no longer the case, says Hayden Foulds, of the New Zealand Rose Society. "We now advise not to use lime sulphur unless you want to get rid of scale on your roses. Otherwise, it is a hassle, as it is incompatible with other sprays and it stains paintwork. Plus it stinks!"
Scale is commonly found on the lower branches of roses and has a grey-white scaly appearance. If you have a problem with scale, lime sulphur can be applied, ideally about mid-June. If applying other sprays, leave for three weeks after using lime sulphur.
For your winter cleanup, copper is the most important fungicide to apply in late autumn or winter, says Hayden.
"Two or three applications of copper are useful until leaves start to be produced. Do one copper spray before pruning, one after pruning and then a third three to four weeks later.
"Even one spray of copper is beneficial, which would be done no less than three to four days after pruning. From personal experience, I have found that disease still arrives, but it's much later if you do a winter cleanup spray programme."
Spraying oil also helps to control scale and mites by having a suffocating effect, says Hayden. "But don't apply copper and oil the same day as pruning, because it interferes with the natural healing process of wounds.
"Also, check the packet for application rates and follow the instructions."
When it comes to pruning, don't prune too hard. "The harder you cut, the less blooms you get, but the better quality they are. So I would suggest removing the dead, diseased and damaged wood. Remove any twiggy stuff and anything that crosses over, etc, then reduce everything by about half."
While it's preferable to cut to an outside facing bud (a bud pointing away from the bush), it is all right to go inwards, particularly if a rose is positioned next to a path. Cut on a slope, away from the bud. Start about five millimetres above the bud, with the bottom of the cut level with the bud. It must be a clean cut. Ragged edges encourage disease and dieback.
"With climbers, don't cut them back hard," Hayden says. "People make the mistake of treating them like a bush rose and cut all the nice long canes back each year, so the plant then has to spend the next season putting it all back on, at the expense of flowers."
Ramblers are a different story. They bloom on wood produced the previous year so pruning is done in late summer, about March or April. "If ramblers are left, they become a big messy tangle and it can be a problem getting them under control again," Hayden says.
How do you tell the difference between a climber and a rambler? Climbers have thicker, stiffer stems, while ramblers have thin, more pliable stems.
Climbers often have larger flowers too. "Just think of something like `Dublin Bay' versus `Veilchenblau' or `Mme Alfred Cariere' or similar."
Once you've finished pruning, clean up the area around the rose plant. Remove weeds and any fallen foliage. Put them in the rubbish, not the compost bin. Then lightly fork over the soil to aerate it. Add compost or well-rotted animal manure.
Hayden recommends applying blood and bone, as well as lime. "This is usually done in May, but it is not too late now. No other fertiliser is needed until the end of August when plants start to grow."
* For more information, see nzroses.org.nz for a New Zealand Rose Society near you.
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