Prepare rose bushes for winter by not feeding them, not pruning them, piling extra soil around the base of the bush, adding mulch and burying the plant. The severity of the winter season determines which preparation methods are necessary.
Stop pruning and feeding the roses around August to encourage the plant to enter dormancy. Do not remove any flowers from the bush at the beginning of winter. Rose flowers wilt away and turn into seed pods, which helps to push the plant into dormancy.
After the first few freezes pass, pile extra compost or potting soil around the base of the rose bush to protect the graft union between the roots and the rest of the plant. You can pile the extra soil as high as 2 feet up the central stem of the plant. Add mulch to the base of the plant after the first hard freeze has passed to further insulate the bush.
In climates where sub-zero temperatures are common during winter, you may need to bury the plant to preserve it. Carefully remove the plant from its place in the soil, and dig a trench deep and wide enough to hold the entirety of the bush. None of the foliage should stick above-ground. Lay the bush lengthwise in the trench, and cover it with soil. Replant the bush during spring.