When is the best time to prune clematis? My sister says March but usually by the time I wait till March, some of my clematis have buds already. I have about 25 clematis in group 2 and 25 clematis in group 3.
You mean flower buds or growth buds?
Mid February is when it is time here so I'd say March probably good for you.
It is very unlikely either type 2or 3's will have any flower buds set in March in zone 5 :-) In most areas of the country, these won't begin to bloom until May. Budding new growth can be removed without fear - it will grow back rapidly. Even here in much milder zone 8, I've pruned clematis back in late March without issue. At most, it might delay bloom on a type 2 a skosh. No probs with 3's.
In Zone 5, you won't have any buds in March. I usually prune around late April, depending on the group.
I'd say late March is when there is growth and in this picture there are buds on 4/10 (Sylvia Denny clematis).