By Bornagain
West Midlands,
United Kingdom 
This clematis was planted in the ground this spring from a minute pot. This is what it has done! It's taken over the trellis and mounting the arch...it's even reaching out to grab the little table and chairs on the tiny quarry patio. Is it safe to keep it? should it be cut right back? It's providing some privacy, but I'm worried about everything in its path including some other clems:-)
17 Aug, 2011
Answers
Phew, thanks Ba, I think you're right about its being orientalis. Not the most beautiful clematis, but it sure is vigorous:-)
18 Aug, 2011
Previous question
It is either Clematis tangutica or C. orientalis (more likely). They can be cut back as hard as you like, even to six inches or so above the ground, before growth starts next spring. The one growing up the side of our shed gets a severe haircut at any time of the year if it needs it. Thought that we had lost it last winter as it seemed to have died completely. Not to worry - yellow flowers on the shed roof as I type.
17 Aug, 2011