Clematis sieboldii (Clematis florida var. sieboldiana) is a striking vine that bears white flowers with a purple centre. It will quickly clamber over a fence, wall or trellis to provide colour in the spring and summer garden. All clematis require pruning to keep them in the framework you've chosen and to promote blooming. The time to prune, and the method, depends upon the type of clematis. The Florida group, of which sieboldii is a member, flowers on stems that grow from one-year old wood, so you should prune them immediately after flowering.
Remove any dead or damaged stems.
Cut back the entire clematis sieboldii to within 3 inches of the desired framework. When you make the cut, do so 1/2 inch above a pair of buds.
Rake the bed to remove all pruning debris, bag it and dispose of it.
Place a 3-inch layer of compost on the soil, completely surrounding the base of the clematis.