Paulownia budding from lopped branch

I cut back my paulownia last autumn and placed some of the branches at the back of the garden in a shaded spot. To my surprise one branch has 4 buds developing along its side and I wondered if I could probogate this. The branch is about 6cm diameter and 40cm long. Maybe I just stick in soil/compost keep it well watered and hope for the best. Would it help to cut the branch down a bit and perhaps halve it longitudinally?
Any suggestions gratefully appreciated. Thanks.
Brian Roberts