Bonfiring them is not obvious to me. I would compost them Pete, chopped into six inch lengths, they should all decompose and add good minerals to your heap. Also at this time of year there should be plenty of other ingredients to help them rot more quickly.
If left under a manure mulch, and with some root on, they may re-grow. If without roots they could be put there, but I hesitate to put too much green matter on soil for veggies, because of increasing the slug population.