Answer: If you haven't stopped fertilizing your roses yet, you should stop now. Generally, it is a good idea to stop fertilizing roses in early August. If you fertilize beyond that date, you can get a flush of new growth -- just when the plant should be winding down and preparing for winter dormancy.
Also, stop deadheading (removing the spent blooms). Instead, let those blooms stay intact and form seedpods, or "hips." The formation of hips signals the rose to stop growing. It's important that roses are in a full state of dormancy before the really cold weather hits. Once your roses are dormant, it is time to apply the winter protection.
Begin by cleaning up the rose bed, removing all leaf litter from the ground and the top inch of mulch. There are many diseases that overwinter in leaf litter, so good housecleaning in the fall is essential. Some gardeners go as far as plucking off any leaves that are still clinging on the canes. Next, give the bed a deep watering. The roses need a big gulp before their long winter's nap.
Here are two options for protecting roses: 1. Cut canes back to 2 to 3 feet tall after they're dormant. Cover the crown with a 1-foot-deep layer of bark mulch. The mulch will protect the crown and allow air to circulate. Don't use soil, leaves, or grass clippings as they tend to hold too much water, which can cause rot. Then wrap the canes with burlap to protect them from drying winds.
2. Use purchased rose cones. Choose ones with an open top so the heat won't build up inside, and be sure to anchor them well so they won't blow away. These cost more, and it's not clear if they provide any better protection than the first method, but they are more convenient.
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