Winter rose protection
I’ve grown several types of roses over the years, some more fussy with their care than others. But like most gardeners, the big dilemma in the fall is when to cover them up for the winter, and how.
Dennis Patton is an extension horticulture agent at Kansas State University. He says in the old days, the recommendation was to wait two-or-three hard freezes for the plant to go dormant, and then you could cover them up. Now, you don’t have to wait.
"The thought initially was that if you mulched them you prevented them from going dormant, and setting them up potentially for winter kill. But what research has found is that the roses are smarter than we are. They know because the days are getting shorter, the temperatures are getting cooler, that they need to go dormant," says Patton. "And so it really doesn’t delay that natural process like they once feared."
Patton says in most areas of the country, roses should be covered up at least by Thanksgiving.
How you protect them depends on the type of rose. The very-popular knock-out roses are hardy and need very little winter protection, maybe just a few inches of mulch around the base.
On the other hand, hybrid teas, grandifloras, floribundas, and miniatures are much more sensitive to freezing temperatures and need a cozy winter blanket.
"The traditional option and probably the most recommended option is to put a mound of soil about 6”-8” deep right over the center of the plant. And then that protects the graft union, that protects those lower canes from the harsh winter conditions," he says.
Patton doesn’t recommend Styrofoam rose cones. He says they can heat up quickly on a sunny, warm winter day and if the plant breaks bud too early, it can be damaged.