The two main ways to propagate clematis besides via seed are by taking cuttings or by layering the plants. If the land is vacant or untended, why is digging them up, after asking permission, not an option? Potting them up after digging would not require waiting until fall to do so.

thanks for the suggestions - the problem with digging them up is that there is no one to ask permission from - taking a snippet would be unnoticed but digging up the plant might look to the neighbors that I was looting the property, anyway too much work.
Can I take a slip and start it now?
Nik

Generally speaking, taking cuttings when plants are in flower generally do not give good chances for the plant to root. If they are in bloom now, wait until they finish blooming to take your cuttings. If you Google propagation of clematis by cuttings, you will find a wealth of information. Below is one such article.

Good luck!

Here is a link that might be useful: clemais by cuttings

I have celamits that seems to be done blooming but has the (bud ?) left from the flower. Woould I be able to get seeds to start more plants? I am a novice gardener, if it dosn't show. Thanks for any help you can give me.