Rose Pruning Time is Here
by Michelle Le Strange, UC Master Gardener Advisor

It's time to prune the roses, which for many people is the most intimidating and confusing of all garden tasks. It's a little scary - won't cutting off all that growth ruin the flowers? It's confusing – since everyone seems to give different advice. And it can be painful - doing battle with a few thorny branches can make you throw down your shears and go back in the house!

But it doesn't have to be that way. How to prune hybrid tea roses in the Central Valley boils down to a few simple guidelines.

Why prune roses? Besides maintaining the plant's overall shape and appearance, pruning rejuvenates rose bushes. A pruned rose bush will be healthier because it will have better air circulation through it and that will minimize incidence of botrytis and powdery mildew diseases. Pruning also removes dead and diseased canes, which encourages new buds to push at the base and renew the canes. Finally, pruning will produce larger flowers and spur shoot growth. In general, the more severely a plant is pruned the fewer flowers it will have, but they will be of larger size.

When should I prune? The usual advice is to prune when the rose bush is dormant, but roses never go completely dormant here. Although there will probably still be some leaves on your roses, January is the correct time for us to prune.

What do I need? Arm yourself well. Wear a long sleeved shirt (or two) and leather or rubber gloves to protect yourself from thorns. Round up a sharp pair of pruning shears and a pruning saw to remove old canes. Since you will want to remove and dispose of all clippings and foliage, clean-up might be easier if you spread plastic or old sheets under each bush as you work. Then you can dump it straight into the yard waste disposal can.

How do I start? Start by pruning out all twiggy growth less than a pencil in diameter. Prune all dead, diseased, or crossing canes to the base. Be sure not to leave stubs, which will die and invite disease. Suckers, the growth coming from below the bud union (the knobby area at the base), should be pulled off, not cut.

What shape do I want? Your goal is a vase shaped plant with an open center. So choose 3 to 7 (depending upon size and age of bush) healthy green canes that can provide this general form. An older vigorous plant can support more canes. Selectively remove older canes (those with rough brownish bark) right to the base. Don't worry, this encourages new canes to form. Throughout the years try to keep 1, 2, and 3 year old canes on the rose bush for best flower production over time.

How far back do I prune? You have a choice. You can shorten last season's growth by about one-third and still have an abundance of large flowers. Or you can leave canes 12 to 18 inches long, depending on your pruning objective. The longer the cane, the more flowers, but smaller in size; the shorter the cane, the fewer flowers, but larger in size.

How do I make my cuts? Prune at outward facing buds so the bush will continue to grow with a vase shape. Be sure that all cuts are just above a bud – neither too close or too far away. Ideal cuts are at 45-degree angles and parallel to the direction of the bud. A simpler way of saying that is… Make cuts as close as possible to the buds at a slight angle. Use sharp pruning shears to make a precise clean cut. Cuts don't need to be sealed.

Is that it? Almost. Now clean up all the fallen leaf litter and old canes and dispose of them. Don't put them in your compost pile or leave them lying around to spread disease. Now's a good time to spray roses with dormant oil to destroy overwintering insects and their eggs. Fertilize just as the leaf buds begin to swell.

What about other kinds of roses? For all roses, first remove dead, diseased, spindly, or criss-crossing growth. Grandifloras are pruned just like hybrid teas. Floribundas and miniatures should be pruned back by one-third, and a few older canes removed each year. Shrub roses should be pruned to fit the space designed for them. Tree roses should be pruned back by one-third to one-half to keep them from becoming top heavy. Climbing roses are trickier. Horizontally train main canes from bush base by attaching to fence or trellis. Prune canes arising from main canes (called laterals) down to two buds.

Want some hands on pruning tips? Plan to attend a free demonstration conducted by the Master Gardeners of Tulare and Kings counties. Meet at 10 a.m. in the rose gardens on January 19th at the Old Hanford Courthouse and January 26th at the Tulare County Courthouse in Visalia.

January 17, 2002