Posted: 15/09/2016 at 22:53
You can make most clematis flower when you want them to do, within reason. For example, the Large Flowered Hybrids are split into 2 groups, Early and Late, easy to adjust these by altering pruning regimes. Your montanas are Group 1, flowering on old wood in May/ June, then they will put a few flowers on in September, on new wood. The viticellas, viornas and many of the species can be controlled by pruning, some plants respond well to only pruning half of the stems, to give a continuation of bloom.