Peter Cundall: Tips for ensuring rosy results until autumn
Gardening guru PETER CUNDALL says in order to ensure better colours, longer-lasting buds and stronger-growing, healthier and all-round marvellous blooms on your roses in autumn, summer pruning is a must.
Summer pruning stimulates the formation of new shoots and almost all produce new, long-lasting roses in about eight weeks’ time when conditions are cooler
Most hybrid tea and floribunda roses produce about three major flushes of bloom during the growing season. The first is from late November until late December, always on new healthy growth.
There’s another blooming during January and early February and final displays of roses occur from mid-April until early May, depending on variety and how and when they are pruned.
However, roses in January can be a bit disappointing because temperatures are high and sunlight fierce. This causes blooms to rapidly fade, usually becoming fully blown, pale and bleached shortly after opening.
There’s no point in allowing highly attractive roses to be wasted during hot weather. So when temperatures start to get too high I get busy with my secateurs to prevent further, wasteful blooming and to force a postponement until cooler conditions prevail.
That means cutting off all withering flowers and even developing buds. On average, each bush rose is reduced by a third, congested branches thinned and any miserable-looking, skinny branches cut out altogether.
Summer pruning stimulates the formation of new shoots and almost all produce new, long-lasting roses in about eight weeks’ time when conditions are cooler.
I should add that suckers — where rootstocks starts to sprout from below graft unions — are always a problem with top-heavy bush roses. If not secured to stakes, even slight winds cause them to wobble back and forth, tearing roots and causing suckers to sprout from damaged areas.
Cutting suckers back hard while still actively growing gives far better control than doing the job in winter.
Ground cover roses are so tough and resilient, they can be slashed back almost to the ground using brush-cutters or hedge shears once blooms shrivel. They
cannot sucker because, unlike most other rose plants, they are not grafted. In fact they are among the easiest of all roses to propagate from cuttings at virtually any time of the year with almost certain success.
Old garden roses bloom only once so can now be either deadheaded or old, woody branches cut right out, almost to the ground.
All pruning debris must be carefully collected, raked clear and carted off to prevent reinfection from black spot disease.
A rose garden may appear devastated after a good summer pruning but colourful annuals can carry through plenty of colour.
If a few large-flowering gladiolus corms are shoved into the soil between the roses in early spring they would be coming in to bloom in January and February.
The most important job after summerpruning is watering, followed by feeding. Don’t ever make the blunder of placing sprinklers among roses. That’s asking for black spot disease to go berserk. This disfiguring, growth-weakening, parasitic fungus is spread by water splash on the leaves, the main reason why roses grown in Sydney or the subtropics where summer rains are common, are often riddled with black spot.
Drip irrigation is perfect for roses and it’s easy to install one dripper per plant to avoid getting the leaves wet.
An alternative to drip irrigation is too deeply water roses early in the morning so wet leaves dry off quickly.
Rose plants thrive if mulched heavily using any kind of straw or organic matter. It can even be pushed hard against stems without problems. Chuck a couple of good handfuls of blood and bone widely around each plant and wriggle it into any mulch. The smell of blood and bone is also a way of deterring possums and wallabies.
Poultry manure, either decomposed or as pellets is a valuable source of nourishment when spread generously around roses. Try and get the stuff on before the end of January if you can and always water the ground first and again after the fertilisers have been applied.
Summer pruning ensures far more roses in autumn, better colours and longlasting buds and blooms on stronggrowing, healthy plants.