I have what I think is a motana group clematis possibly jacqui. It is very large with lots of dead wood underneath. What I want to know is if I prune it well back now should it survive or should I prune at another time, if so can I prune it well back as if to start again. As you can probobly tell I am very much a novice gardener so hope this makes sense.
If what you have is Clematis montana then it should be pruned ligthly following the summer's flowering season, since next season growth and flowering will be on "old" wood. If it has lots of woody growth you can prune it back to within two or three feet of the ground level. At worst, you may lose one season of flower production, but any following flowering will be more vigorous...
As advised pruning montanas should be done immediately after flowering. If yours is very large you can give is a really good hard cut back. You wont do it any harm except probably loose next years flowers. skylight