I grow most of my mature lily bulbs in black pots, and haven't cooked them that way.... yet! Can always hide a pot beneath foliage in the garden somewhere during summer. What does happen sometimes though is potted bulbs might get too dry in autumn. I think the bulbs lose alot of active roots and get flabby, then when the winter rain comes, they can't cope with the sudden moisture and rot. I think they rot because they got too dry, not necessarily because it was too wet.
I remember that one now, Anthony! Nice. Have any pollen to spare, perchance? Can we scale it?
From this morning, Patricia's Pride and Crossover:
