You don't have to plant anything.........unless you want to. The "roots in shade" thing is a bit of a myth. It is not really a shaded position for the roots that is necessary but a consistently moist root run. Clems hate to dry out. A low spreading plant will help to retain soil moisture but so will a decently thick layer of mulch. Or even a rock or flagstone placed at the base of the vine.

I grow all my clems in containers and none of them have any plants to shade their bases.

I agree. They don't like shaded roots. They like non dry soil. Shaded roots help keep the soil moist. But that's it.

Thank you gardengal and Charles. I'll just add bark mulch and nothing else. I appreciate your help.

perennial geraniums..