Spring (May-ish) plus a 2nd flush of bloom (August-September-ish) Prune the early-flowering clematis types like Clematis alpina 'Constance' and Clematis montana 'Elizabeth' immediately after they've finished blooming. Prune large-blossomed, late-blooming clematis types like Clematis viticella cultivars in early spring, just as the buds begin to swell. Clematis plants, including climbing vines and spreading varieties, feature large, colorful flowers.Growing them is fairly easy, but pruning clematis tends to instill fear in some gardeners. The alpina, macropetala and montana clematis fall into this category (Group or Type 1 or A). Ex: Clematis alpina, C. armandii, C. cirrhosa, C.macropetala, and C. montana. Nelly Moser belongs to Group B so prune in late winter or early spring. Or leave them alone. The alpina clematis offers a beautiful purple blue bloom. Clematis alpina (Pruning Group A) We found that the Pruning Group A clematis (alpinas and macropetalas) and the large-flowered spring-blooming Pruning Group B clematis both had new leaf growth tight to the vine in early spring, and many were already showing flower buds. This fear is unwarranted, as pruning simply comes down to when your clematis blooms. This gorgeous Passion Flower Clematis, Clematis florida sieboldiana can be pruned if necessary while dormant. These types of clematis bloom on old wood. Discover our articles devoted to clematis; Both easy and early, you will enjoy its abundant flowers from the spring. Pruning is optional, right after flowering, if they get straggly or overgrow their space. In summary, what you need to know: Last name: Clematis Alpina Family : Ranunculaceae Type: Climbing Height: 3 m Exposure: Sunny, partial shade Ground: Deep and fresh Foliage: Obsolete Flowering: April to May.