Why have the leaves on my Clematis turned brown?
Browning of the *lower* leaves seems to be a normal occurrence with some cultivars of clematis. It usually happens in the heat of the summer after blooming time. Current knowledge suggests there is little that can be done other than to make sure that the plant is well watered and has a thick layer of organic mulch around its base to conserve moisture. Just prune away the dead leaves and leave the vines alone. Many times the leaves can just be crushed and they will fall away.
Another type of browning leaves happens when the plant, or part of the plant, has suffered from 'wilt' and that portion has died. In this case the brown leaves extend to the growing tip and the vine becomes very brittle, almost black, and the axil buds are also brown or black. It takes some experience to determine whether this portion is dead. If the tip is bent and it snaps off cleanly, it is dead. Prune this down to either a living branch, live leaf axil, or to the base. The plant may be dormant for a period, but if kept well watered and fed you should see new growth shoot either later the same year, or the following year.