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January 26th, 2009 by Temple City Tribune
Dear Garden Gal,
It’s my first year in our new home. The house came with a small, very pretty garden in front with 13 rose bushes. I’ve never taken care of roses before. Is it time to prune? How do I do that?
Agog in Altadena
Many plants, like roses, head into carbohydrate-storing mode when temperatures dip below 55 degrees. By this time of year, when nighttime temps reach 45 degrees, they’re resting in dormancy. Even with our warm sunny days exceeding 70 degrees, the cold nights and the daily temperature fluctuation of more than 20 degrees puts roses out of their growing season.
We prune plants in Southern California when they’re dormant. The estimated height of winter dormancy is January 15, but for most gardeners, rose pruning takes place from December 15 to February 1. I’ve pruned roses as late as March 1 when the winter’s just gotten away from me, but the best prune by mid-January.
In case your roses are still producing new leaf growth, you can encourage dormancy by withholding water.
Before you prune anything, know your wood. Plants bloom on one of three types: current season’s wood, last year’s growth (shoots) and older wood, two to 10 years old (spurs). Roses bloom on current season’s wood, which makes them easy to prune. Easy, that is, if you don’t mind a few thorns.
When you cut keep a few goals in mind. Cleanliness will help ward off later troubles. Prune with a trash can nearby. We don’t compost rose clippings due to overwintering pests and diseases. For shears, Clorox is tough on your blades but can stop the transfer of bacteria onto your next cut.
As you prune, remove dead and diseased wood. Pests thrive here. Borers love sections that have died back, and roses usually have at least one area of dieback. Be sure to cut away any cane that has a hole in the center or pith. Keep cutting till you get to green wood. Throw those canes in the trash, not onto the ground. Borers can hop out and burrow into the ground till finding another cane to eat through. Rust can splatter off leaves onto the soil, too, so take care to get your cuttings into the can ASAP.
Another minder for pruning. Cut your rose plant in the shape of an open fist. Generations of students from Cal Poly Pomona to Mt. San Antonio College have been admonished by Professor Dave Lannom to cut like an open fist. And he’s right! Hold your hand like an open catcher’s glove. This is the pattern to emulate as your prune. Keep the center open as roses love good air circulation around and through their canes.
How many canes should you leave? Remove anything old, anything skinnier than a pencil, clean out the interior and any crossing or rubbing canes, and remove any that prohibit the free circulation of air.
Cut to a five leaf group just above an outward growing bud. This is where new growth forms in the spring. From this bud’s new wood a flower will be produced, and more each time you prune throughout the growing season. So shape your plant to encourage outward growing buds. It’s not the end of the world, but it doesn’t help to cut a bud on the inside, as this bud will soon become an air-blocking inward growing cane.
Generally, the hardier your roses (canes thicker than a Sharpie) the harder you cut the canes. Plants that grow four to 10 feet tall benefit by being cut back to 12 inches. Plants that grow two to four feet tall should be cut back to 18 inches. Small rose shrubs or groundcover roses that don’t grow taller than two feet should be lightly tipped back.
For all roses, strip away any remaining leaves. Spray with a dormant spray for mites, borers, black spot, rust, powdery mildew. After pruning is finished dig in ¼ pound superphosphate per rose. This will kick start the plant’s root development in spring for an abundance of blooms.