I have accidentally chopped off the flowering stems of my clematis cartmanii
Is it possible to encourage the stems to root?
Vendée, Western France
You can try rooting cuttings but, in my experience, they're fussy.
Have a read of this -
"We don't stop playing because we grow old; we grow old because we stop playing." - George Bernard Shaw
Doubtful hopefully the plant will regrow as the roots are still there, just be patient as it might take a while.
I'm not knowledgeable about stem cuttings but I do know they shouldn't dry out so it's probably too late.
I've done that many a time, no matter how carefully I think I'm pruning. Most clematis will re-shoot from the base okay, keep it well watered and fed and cross your fingers.