This is mahogany season in the rose garden. The first flush of dark red foliage is coming out strong. It’s a sure sign of spring.
But what if you never finished pruning your roses? They’re already covered with new growth. Some may even have blooms!
What’s a rose lover to do? If you haven’t finished pruning, prune anyway. Not all the way down to 36 inches (or lower) in height, as you may have pruned in mid-winter, but do give your roses some careful attention. At least cut out the deadwood and damaged canes, plus take some of last year’s growth off the top. Otherwise, your bushes will tower over your head by summer. It’s hard to smell the roses when you can’t reach the blooms.
If buds have already formed, you can put off this late “haircut” a little longer. But make a point of cutting those first roses for a long-stemmed bouquet (and then finish that pruning).
The idea is to set your bush up for success -- a season filled with beautiful blooms, not just those first flowers of spring.
With warmer temperatures, rose bushes grow rapidly. This first full week of spring is expected to see a push into the 70s by Friday. This early warmth likely will bring early fungal disease outbreaks, too.
Powdery mildew and blackspot love afternoons in the low 70s. Inspect new foliage on your roses for signs of trouble.
Both fungal diseases can overwinter in mulch under the bush or on old foliage. (That’s why you strip off all those old leaves when you prune.) You’ll most likely notice yellow and black splotches (the warning signs of blackspot) on leaves the bush held onto over the winter. Remove those infected leaves now and dispose of them. Otherwise, blackspot will infect all the new leaves, too.
Powdery mildew looks like powdered sugar was dusted on the foliage and buds. It can appear almost overnight. If possible, move infected plants away from others. Infected foliage will die and fall off; make sure to discard those dead leaves. After this spring outbreak, the bushes will grow fresh, healthy foliage.
Powdery mildew is very temperature sensitive. Although it likes it warm, it can’t stand higher heat. When Sacramento hits 90 degrees, this fungal disease disappears.
Right now, you can stop an outbreak before it happens. Powdery mildew starts with a spore factory, usually on the bottom of a leaf. Before it ever shows that dusting of white, the leaf will look puckered and deformed. Sometimes, it appears as if it was stung, with a puckering on one side. Clip that leaf off the bush and dispose of it. Eliminating that one leaf will prevent a powdery mildew explosion.
Watch out for aphid invasions, too. They’re attracted to rapid, tender growth – especially new buds. Blast them off with a strong spray of water.
Speaking of water, now also is a good time to get ready for dry and hot months to come. After a very dry winter, our landscapes may need some early deep irrigation and TLC.
Make a habit of checking the moisture in your rose beds. It’s easy; just plunge a long-handled screwdriver into the ground. If it penetrates down 6 inches easily, your soil moisture should be fine. (The exception is new planting mix; it stays pretty loose even when dry. Raised beds also tend to stay looser when dry.) If the soil is rocklike and impenetrable, water deeply; your roses will be thirsty.
If setting up an irrigation system, figure that each full-sized bush will need about 3 to 5 gallons of water a week, depending on soil and location. Roses in sandy soil or containers need more. So do roses that get full sun all afternoon.
How do you retain just the right amount of moisture around your roses? Remember: Mulch is your roses’ friend. Use wood chips, ground bark or similar mulch. Don’t surround roses with rock or gravel; it retains too much heat and cooks their roots.
Start feeding your bushes this month, too – but not too much. High doses of chemical fertilizer will speed up growth even more – and attract more aphids. Slow-release organic fertilizers are preferred. Always make sure your roses are irrigated BEFORE you feed them.
One more thing: Watch out for weeds. They compete with your rose for water and nutrients. Keep the area around your bushes weed free and mulched; you’ll have less work and your roses will stay happy.
For more on roses, check out these tips from the UC Cooperative Extension master gardeners: