Hybrid tea roses are the most tender type of rosebush.
image by DRW & Associates Inc, Creative Commons
By the 1970s, roses had gained a reputation as a plant that required special care. Compared to the hardy shrubs and climbers of earlier times, hybrid teas and grandifloras, although still classified as herbaceous perennials, were not nearly as hardy. Today, roses are bred for every growing zone and gardening skill. Most of them are technically shrubs, and many can make it through all but the most severe winters with a bit of protection and the right type of care.
Know your rose. Rugosas need little attention, but floribundas and grandifloras need serious winter protection, and teas just don't survive in northern states. Practice good care for your rose during the growing season; fertilize it properly and prune the deadwood all summer long, so fall cleanup will present a minimal shock.
Fertilize until dormancy starts to set in---In November in most parts of the U.S. Give the shrub one last feeding of 1/2- to 2/3-strength fertilizer and trim out only deadwood. Don't prune until spring---pruning in fall can lead to increased winter die-back on branches. Keep watering normally to help your rose store up for early frosts and freezes.
Beginning after the first hard freeze (which kills all the aphids and pests), it's safe to start "mounding" shrubs. Use a rake to clean all the summer mulch, leaves and debris from around the base of the rose to take away any surviving bacteria, and loosely pile about 10 inches of garden soil from some other part of the garden around the base of the rose, covering the graft---the knobby place on the plant's main branch where the upper hybrid plant joins the root stock.
Cover the entire shrub a week or two later with mulch made of pine needles or branches, sawdust or clean compost. If the shrub is large, wrap a cage of chicken wire around it and stuff the mulch in around the shrub. Tie burlap around large shrubs; the main reason for covering your rose is to protect it from cold winds, not keep it warm.
Bury long-branched shrubs or climbing roses by digging trenches and laying branches or canes in them, then covering with heavy mulch. Use "rose cones" as a last resort in place of mulch, but take care not to bend branches against the rigid plastic, and remove them as soon as the sun begins to warm the ground in the spring. As an alternative to the rose cone, surround shrubs with burlap wire and fill with packing "peanuts."