Welcome, Kim! Oh doesn't that paint an idyllic picture ? I wouldn't think either would kill the other - overwhelm, possibly, so you'd have to be judicious in how you prune the grapevines - they can run riot given the right circumstances. We have a couple of clematis that grow quite well, and they are planted at the foot of an immense fig-tree. What type of clematis are they? If they are montana-type, however, and already thriving, you may need to be quite enthusiastic about pruning both. The combination of the two plants sounds delightful. We are planning to grow vines up (when OH gets round to building it) a trellis linking our summerhouse to the balcony fence, so we have a shady canopy to sit under in hot weather, so I'll be interested to know how you get on. I'm going to try and post a photograph I took of a summer scene in Cyprus that is my idea of heaven: drinking wine under the vine that produced it!

Hi Kim are you in the UK and if so which part of? Grapes will not grow outside in the north of the country, well they will but you wont get any fruit.

If you'd like an idea for an ornamental grape vine which is a stunner, look at Vitis vinifera 'Purpurea'. I have Clematis viticella 'Polish Spirit' growing through it, and it does look lovely. The grapes aren't edible, unfortunately....too sour!