I planted 2 clematis vines last year, a Nelly Moser and a Niobe. Both plants had only a single vine growing, so once they were about 16″ tall, I pinched them off just above a pair of leaves. I was under the impression that this was necessary to encourage the plant to sprout multiple vines. Unfortunately the plants both stopped growing immediately after I pinched them. Now I notice they’re both growing again, but again with only one vine each. I’m hesitant to pinch them off again after what happened last year, but I also don’t want spindly clematis either. Any suggestions or hints as to what I did wrong?
Both are lovely clematis … Niobe is a personal favourite of mine! You didn’t say when you planted these vines. If you did so in later summer or fall, then they may not have had enough time for the shoots growing below the pinch to develop fully. Pinching should not harm the vines at all; in fact, it is recommended.
The British Clematis Society provides some detail on how and when to pinch: “Prune down to lowest pair of growth buds in early March and pinch out the growing tip on each new shoot as soon as it makes two pairs of leaves. Pinch out again when the shoots from these new leaves have also made two pairs of leaves. If growth also starts again from ground level, this too can be pinched out at same two pairs of leaves. This process can be repeated as often as you wish until mid-May, by which time your plant will already have many branching stems instead of just one or two. Pinching out will obviously delay the start of flowering, but now you will have blooms much lower on the plant and no bare expanse of stem.”
Note that in Toronto, you will want to wait until late spring to start the pinching process since you need to be able to see the actively developing buds and leaves.
Here is some websites you may find useful: https://www.britishclematis.org.uk/qa_growing.htm