Rose Family Practice

Wednesday, February 16, 2011

The large category of ‘shrub roses’ covers a diverse array of sizes, colors, and bloom times in both old and new rose varieties. The classics, like ‘The Fairy’, ‘Natchitoches Noisette’ and most Meidiland roses, will be less vigorous without annual pruning. This traditional group gets relatively heavy pruning, reducing the shrub’s size by 1/3 to1/2 overall each year. Newer shrub rose groups, such as ‘Knockout’ and ‘Flower Carpet’, need only to be cleaned up in February and cut back lightly. Additional shaping can be done following each flush of blooms to maintain the shrub’s size and induce more flowering.

Here’s the basic process for pruning shrub roses: Cut the entire shrub rose down by half, or if it is particularly vigorous, by two-thirds, then select the canes you want to nurture. Choose 3 or 5 of the healthiest and remove oldest canes as well as those that are merely shoots. Cut the woody and weak canes down at ground level, leaving only the healthy 3-5. Clip off the twigs along the canes and some of the side branches. Like so many techniques, the way you prune makes a difference: try to cut above a bud that faces the outside of the plant to direct new growth, and slope cuts down and away from the plant’s center. Veteran rose grower Johnny Broussard, my neighbor, roots cuttings taken from winter prunings to keep his collection of 2 dozen or so varieties going and to share. He says, “I root at least 5 cuttings from each bush, and end up saving one and giving the rest away. I take long cuttings – 6 inches – and try to take them from the center of the rose.” this practice insures plenty of sunlight and good air circulation reaches the rose. He explains that he sticks the rose stem 4 inches into the soil and leaves only 2 inches above the soil level to provide plenty of places for roots to initiate. “I stick three cuttings into an 8” pot full of good potting soil, water the pots once and leave them outside for a year,” Broussard says, “Just water when the pot feels light, nothing else is needed.” He does soak the rose cuttings in a solution of ‘willow water’ for 24 hours before potting them up. “I put short pieces of pencil-size black willow stems in warm water overnight, then use the water to soak the rose cuttings,” he says. In 20+ years of growing rosebushes, Broussard admits he has tried rooting hormone, too, and sometimes uses nothing yet the cuttings still root. “They’re just easy to root this time of year,” he says.

Roses for the vase

Hybrid tea roses are most plentiful in the trade, and if you have the time and devotion, they can be rewarding with spectacular large flowers. Cut them back to 18” tall and leave only the largest three canes per plant. In my own garden, I compromise by growing the virturally pest-free, old tea rose ‘Aloha’. It produces many fragrant pink flowers each year on sturdy canes that have very good vase life.

Spare the climbers

Unless the canes are slapping you in the face daily, do not prune climbing, running, or rambling roses in February. Those that bloom once only, like Rosa ‘Lady Banksia’, must be pruned right after their spring show or their growth becomes rampant quite rapidly. Reblooming climbers should be pruned in fall except for those that will bloom nearly forever without rejuvenation, such as Broussard’s favorite climbers. “I grow a new ‘Red Cascade’ each year, but don’t touch ‘Mermaid’ except to chop off canes that threaten people,” he says, adding, “The mockingbirds love to nest in the ‘Mermaid’ – must be good protection inside all those thorns.”

Care after pruning

After pruning and weeding around the roses, spread a blanket of compost about half an inch deep around the base of each. Cover the ground in a one foot radius around the rose and work the compost into the soil. Mulch on top of that with an inch of loose organic material such as ground bark or pine straw. Broussard warns against overfertilizing old garden roses. “Grow the truly old roses on the lean side or they’ll become gluttons. Too much nitrogen given too often makes more leaf than bloom,” he says. He does occasionally fertilize roses during the growing season, but does it differently from others. Broussard advises, “I spray a half-strength dose directly on the leaves to fertilize the roses. That’s it.”

Great Shrub Roses Aren’t All Old

You may not know it, but the premier breeders of English roses in the world has its US headquarters in our region. David CH Austin released his first selection in 1961 and now the David Austin Roses include 2 generations of namesakes and 200 roses. I’m excited because this year, they’re introducing some of their varieties that are not grafted, that is, growing on their own roots. Now, that’s progress, and I’ll let you know how they do for me this year.

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