Hello. I live in Port Hope. I have an old Kolkwitzia amabilis. I have tried to keep the size of it fairly small, and as a result the bush is now an awkward shape. I might inevitably need to dig it out, as I know these do not look their best when they are not allowed to grow to their desired size. I would, however, like to give it one more chance by hard pruning it and seeing if it will come back to a more pleasing shape. Is it too late this spring to do that? I would like to take it back to about 6 inches from the ground and see what happens.
Kolkwitzia amabilis can take heavy pruning even though it normally doesn’t require it. Cut some of the oldest canes to the ground in the spring. Further thinning can be done after blooming. Kolkwitzia is a spring bloomer so the best time to prune it is after it has bloomed or you may be cutting off all of its buds before it has had a chance to bloom. Here are a couple of links for pruning information. The first is about schedules and the second a very in depth discussion about pruning.
Please note that you may also contact your local Northumberland Master Gardeners group with any gardening queries at northumberland@mgoi.ca