Britesea
Sustainability Master
I was thinking that I might be able to use some to warm up my garden beds a little faster in the spring, by spray-painting them black and partially burying them in the soil and filling with water (maybe with a bit of clear plastic on top to stop the water from evaporating away.) The heat from the water would radiate out into the soil, I hope. They would also work a hedge against late and early frosts.