Have you tried wire "baskets" to keep gophers from chewing up your dahlias, roses bushes, etc? Nurseries in this central part of California are strongly suggesting we gardeners use them. The gauge needs to be smaller than common chicken wire, of course, and the best tool is a pair of needle-nosed pliers-- after you have cut a piece to be folded and joined down one side and across the bottom. ( A dahlia requires a piece about 10-12" deep and 20 " around. Dahlias like to be planted pretty deep, with fertilizer added in the bottom, so this size would protect the longest tubers you have.) Folded in half, the wire will be 10" across at the top, and when you have bent the cut edges together down the side and across the bottom, you will have a "pocket" to plant in. In the Fall you know exactly where to dig, if you live where plants need to be lifted and stored. The process IS a lot of work, but after losing both roses and dahlias the answer is worth the trouble.