When two prune clematis?

It depends what type of clematis it is.


If it is a spring flowering one it is too late this year - but for summer through to autumn flowerers you should be OK to do it know through to February (they flower on new/current year growth)


Spring flowerers grow on last year's growth.


Generally though - prune within a month of end of flowering to ensure flowering in the following year.

When two prune clematis?
Agreed. It depends upon the type, spring bloomers should not be pruned in autumn; it takes their flower buds away. Prune after the first flush of spring bloom, then they will develop more and flourish.
Reply:Yep, as above
Reply:There are essentially 3 types of clematis for pruning purposes.


Spring flowering clematis like C. montana and C. alpina, flower on wood made the previous year. Remove flowered stems, after flowering.





Large-flowered hybrids that flower before mid-June: in February, remove all dead wood and cut back to the first good pair of buds.





Jackmanii, C. viticella and other autumn-flowering clematis: in February, cut back all stems to 12" above ground level