|very old clematis - blooms on old wood. I want to cut if back to install new trellis. When should I cut it down?|
|If you want your clematis to flower next year, you'll need to determine exactly which type you are growing: The earliest flowering clematis bloom on old wood, while later flowering types must produce new growth in order for flower buds to form. Plants in this group bloom in early spring, generally in April and May, from buds produced the previous season. Prune these plants immediately after flowering, but no later than the end of July. This allows time for new growth to produce flower buds for the next season.
The second group of clematis that flower on old growth are large-flowered hybrids. These bloom in mid-June on short stems from the previous season's growth and often again in late summer on new growth, though these blooms are usually smaller. Prune these types in February or March by removing dead and weak stems, then cut back the remaining stems to the topmost pair of large, plump green buds. This cut could be a 6 inches to 18 inches from the stem tips.