Answer: The President clematis is one of the large-flowered varieties that begin to bloom in May or early June with the first flush of flowers appearing on the previous year's growth, followed by a smaller flush on new growth.
The easiest way to prune this group is to cut the vines back severely every few years, thus only sacrificing the early blooms once out of every 3 or 4 years.
You can also visually divide the plant in half, and severely prune each half in alternate years.
A third way to prune them is to thin out lightly and disentangle stems before growth begins, then go over the plants again after the earliest flowers fade, severely shortening the stems that have borne those flowers. This method would be done annually.
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