Rain Barrel Freeze Protection: Drain Before Hard Freeze, No Safe Antifreeze

No plant-safe antifreeze exists. Drain barrel if a week of sub-25°F temps forecast. Otherwise, daytime thaws prevent freezing. Spring rains will refill it.

I currently have a full rain barrel and a full 275 gallon water tank. I won't worry until we have a week of temperatures constantly below 25 degrees, at which time I'll drain them.