In answer to your question, Judy, the mulch is there to minimize the temp. fluctuations on the plants. You wait until the ground freezes, early in the season, so it,s not a deep freeze, and then, mulch your plants. Good deep mulch in your area. Then, as winter progresses, especially later, when there,s alot of freezing and thawing, ( Feb/.Mar), the temp around the roots of your roses remain stable until all danger of frost has past. In Hamilton, Ont. where I live, we experiance this freeze/thaw problem alot more ,as our winters are influenced by the great lakes.If the plants are allowed to thaw out before it,s time for them, they risk beginning to form new growth or at least, the sap running in the canes, which, a sudden subsequent freeze, would kill them, by causing them to burst. You also don,t want to mulch your plants too soon, as mice,and other rodents also would use your roses as a snuggly place to go, with nice stems and canes to chew. So wait until those guys have bedded down somewhere else..:P..(if your handy traps/ hunting cats don,t get them first..) Hope this sheds some light on your question. Happy growing! Lenage.