My plants are against a trellis and I don't tie them in.

As the plants grow in height I just feed the leaders through the trellis and they tend to find there own way from there.

On the odd occasion I have had to tie wayward leaders in I use soft twine ( I think it is hemp)

What support are you using for the clematis to grow up, Marghay? and do you know what variety of clematis you have?

I've got one, miss Bateman against clematis trellis; the other 2, hagley hybrid, general sikorski are against overlap fencing and I planned on putting some wires up as they grow. There is trellis at the top of the fence. Thanks for responses

You would be better to attach clematis netting or even pea netting to the overlap fencing for your clematis to climb up, they are twiners so don't cope very well with wires.

Well they're not really twiners, MG - the varieties mentioned are petiole climbers, so, as MG suggests,the best thing is to put a run of clematis mesh from the top of the trellis down to the bottom of the fence. Cheaper than clematis mesh, though, and much less visible, is green coated chickenwire - comes on a roll, about £8 in Wilkinson's. Use U shaped fencing staples to attach either with. Note they will not attach themselves to your trellis at the top either - they need thin supports to cling to.

Thank you all for the advice & tips. Much appreciated!