I had a piece of comfrey in a pot with my other potted plants. I always knew it was time to water when the comfrey went limp.
I lost it two winters ago when the rains of winter didn't come. I had quit watering because it was the 'rainy season'. I didn't notice my comfrey was dried out. It had survived for many seasons before that. I'm still looking for someone local who can give me a new piece.