If you have any perennial flowers, don't cut them down. 3 years ago I forgot to cut off the the stalks from my Yucca's and it turned out to be a very harsh winter. In spring of 2013, the stalks were all gnawed and shredded from animals looking for food. Trimmed them off in the spring and everything grew back normally. Haven't cut them off since and am leaving all my other perennials intact this winter for the wildlife - just in case.