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Cool, wet weather creates a profusion of roses

Cool, wet weather creates a profusion of roses



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June's cooler temperatures and abundant rain created some of the showiest, largest and longest-lasting rose blooms in recent memory.

Now what should you do to care for your roses and keep them blooming?

To help you in your quest for better roses, I spoke with Lance Walheim, an author and nationally known rose expert. Two of his rose books are "The Natural Rose Gardener" and "Roses for Dummies," and he has contributed to or authored more than 30 other garden books.

I became acquainted with Walheim when he was a staff editor at Sunset Magazine and he kept track of conditions in the Intermountain region. He is also the garden expert for Bayer Advanced Lawn and Garden Products.

Walheim explained that there are several things you need to do to keep your roses blooming throughout the summer. "The first thing you must do is start with the right variety. Local information is always the best, so I recommend people get in touch with the Utah Rose Society and get their list of recommended varieties."

All roses are not ever-blooming. Old-fashioned roses, native roses, rambler roses and heritage roses are single-blooming types. With these kinds, it is impossible to get them to bloom again.

Walheim explains that there are several other things that help keep the roses blooming.

"Roses are heavy feeders and need nitrogen fertilizer to keep them producing the new wood that produces the new flowers. I recommend that you fertilize every four to six weeks throughout the summer."

Be certain you don't over-fertilize the roses. You want to keep fertilizing until about mid-August or early September, but make your last application about six weeks before you expect frost in your area to help them harden off for the winter.

Walheim admits that some rose growers recommend against using fertilizers because the succulent growth is more susceptible to pests, but without new growth, you cannot grow more flowers.

Adequate watering also encourages good growth. Walheim recommends deep watering once per week. And roses appreciate a good mulch layer to help conserve water and prevent weeds.

Another important consideration is deadheading.

"Some roses are self cleaning," Walheim explains. "Even the self-cleaning types, like the Knockout roses, bloom better if you keep removing the spent blossoms.

"Once roses set their seed heads or hips, they stop blooming. If you remove the blossoms, they continue to bloom. Most people recommend the rule of cutting them back to the first five-leaflet leaf, but I like to cut my hybrid teas back further than that. Cutting them back more heavily gives the new rose a stronger stem," he said.

"With shrub and landscape roses you can be less selective. With these kinds, you can trim them off with hedge shears, if you want. Just keep the spent blossoms removed to encourage more blooms. Remember that even ever-blooming roses go through cycles and have more blossoms at certain times of the year."

Since our wet June has brought out some seldom-seen disease problems, I asked him to share information on disease control.

"The key to controlling diseases is to learn about the diseases," Walheim said. "Learn what causes them, and then try to prevent them.

Rose black spot and rust prefer warm, humid conditions, while powdery mildew thrives with hot days and cool nights.

He recommends several cultural practices to help prevent diseases.

"Clean up the roses both as you deadhead and in the fall. Most of the diseases overwinter on fallen leaves and twigs. Avoid overhead watering, and if that is not possible, water early in the morning so the foliage has a chance to dry off before evening.

"Watch your plants carefully. If you see black spots appearing on the roses, pull off all the affected leaves. Hopefully, as the weather conditions change, most of the diseases will disappear.

More serious cases might require fungicides.

"Most fungicides prevent disease, and once a plant has a serious disease, it is difficult to control the outbreak. Organic controls include potassium bicarbonate or neem."

Larry A. Sagers

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