Here is what I do in fall (or at least try to most of time) to keep my babies happy! I have adapted this things to-do list to accommodate gardeners in the other parts of the country.
Whack Down Those Weeds
Clean up and remove weeds that can harbor diseases and pests.
The Final Meal
Give your clematis one last feeding before winter comes. In USDA Zones 4-9, do a final feeding for clematis with Gro Power 3-11-11 in early September or 6 weeks before the first frost. In USDA Zones 10 & 11, do a final feeding for clematis with Gro Power 3-11-11 between the end of September and early October. This will tide them over until they are ready to come to life in spring.
Tuck Your Clematis Under a Nice Cozy Blanket of Mulch
Reapply mulch on your garden beds before your clematis take their winter nap.
Time to Prune?
Yes, if you live in USDA Zones 10 & 11 prune your clematis in November. In USDA Zones 4-9 you will wait until February or March. After pruning, to help prevent any stem rot or fungus, apply a Physan 20 drench to soak the plant and planting site.
Nuke Responsibly Any Potential Overwintering Scoundrels
To help eradicate any overwintering insects, spray your clematis with a natural pesticide made with an ingredient such as pyrethrum or with horticultural oil which will suffocate them.
Prepare for Winter
Where the ground freezes, prepare for winterization. Continue to water throughout fall. Protect garden clematis plants from light freezes by covering them with blankets, sheets, cardboard or baskets. (for more information see: Winterizing Your Clematis)