How to Prune Clematis

Clematis are almost the perfect vine. They’re easy and rewarding to grow and have showy blooms and great variety. All they need is sunlight, a little extra water and a trellis to twine. The challenge is knowing when and how to prune them.

For pruning, they are grouped into three categories:

1. These clematis flower in the spring on old growth. Prune them right after flowering so they have the entire growing season to recover. Don’t prune every year.

2. These flower in late spring/early summer on new and old growth. If you hard prune these plants (removing more than a third of their length) after their first flush is gone, the wood you remove might not bloom again, but you encourage new growth that will produce more flowers in late summer and autumn.

3. These vines flower in late summer/fall on new growth. When pruning these, remove as much old growth as possible, encouraging strong new shoots that will produce abundant flowers. These may be hard pruned once they go dormant in autumn.

If you can’t remember what variety you planted, use the simplified pruning method. As soon as the first growth appears, start at the top of the plant and work down, cutting out dead wood on each vine. Stop when you find a live bud or growth. Although the stems of live and dead wood look alike, it is the leafy growth from the buds that indicates a vine is alive. Continue until each vine is either pruned to a new growth or to the ground if that shoot is dead. Then secure each of the vines to the trellis.

If this still feels complicated, simply cut all of last season’s growth to the ground. You cannot kill a clematis by pruning it. The plant will rejuvenate from the base with new shoots. But this method will result in shorter plants and fewer flowers, and the plant will start to bloom a little later. After any repeat blooming in autumn, deadhead your clematis but avoid hard pruning again lest you diminish next year’s spring show.

When you bring it home from the garden center, always prune your clematis when planting it to reduce stress on the plant. Remove the stake in the pot and prune the clematis back to 12-18 inches. If your clematis has flower buds when you bring it home, let it flower in the pot and plant it when flowering is finished.

When you have questions, Colorado State University Extension has research-based answers. The Help Desk opened April 15 at 17 N. Spruce St. Hours are 9 a.m. to noon and 1 to 4 p.m. Mondays and Wednesdays. Call 520-7684 or email CSUmg2@elpasoco.com.