By Sara Creamer
Fayette County Master Gardener
WASHINGTON COURT HOUSE — There are good reasons to prune clematis. Pruning helps create a neat tidy plant. It stimulates buds and flowers. It encourages the plant to be fuller. It allows you to lower the top of the plant to eye level so you can see the blooms.
Accomplishing these goals can be confusing because there are three bloom types that result in three pruning groups. The pruning type relates to when the plant blooms and on whether it blooms on old or new wood (or both).
Regardless of bloom type, a clematis should be pruned to lowest pair of strong flower buds when planted. This stimulates multiple stems and allows the root growth to develop in proportion to the top growth.
Group 1 (or sometimes called A) blooms in late April to late May. They bloom on old wood that developed last year. You should prune this type right after they finish blooming in June. You can remove dead or damaged stems and shape to keep under control but avoid cutting into the main woody stems. Like lilac and early spring blooming shrubs, pruning in fall, winter or early spring will remove all the flower buds that developed during the summer. Do not prune after the end of July.
Group 2 (or sometimes called B) has two seasons of bloom. They bloom in mid-June on old wood and again in September on new wood that grew this year. The June bloom is the heaviest but the September bloom is nice also. These clematis benefit from a light prune of the stems that bloomed in June right after they finish the June flush of bloom. This encourages new growth that will bloom next year. Be sure to remove dead and damaged stems.
Group 3 (or sometimes called group C) blooms on new growth from the current season in June through August. This is the easiest type to prune. They can be cut to living buds about 24 inches above the ground in early spring just as the buds swell. If not pruned these clematis will eventually develop bare stems at the base. The flowers will be at the top of the plant and may be out of the line of sight.
If you keep good records and know the name of your clematis, you should be able to check online or in a good nursery catalog to determine the blooming group to which the plant belongs. Another way to decide when to prune is to pay close attention to when your plant blooms. You can match up when your plant blooms to the suggested pruning timing.
If you prune at the ‘wrong’ time, not all is lost. You will not kill an established plant. You will just delay bloom until later in the season or next year.
I hope you were able to take advantage of a few nice days in February to get outside in your garden. If you have any questions, you can contact your county Ohio State Extension professional or Sara Creamer at 740-335-1150 or firstname.lastname@example.org.