It was fun to watch my VERY COLD dehydrated outdoor potted plants spring back to life after I poured water on the soil. See, the roots of a potted plant with dried out soil can easily be as cold as the air temperature (below freezing). BUT if the soil is damp (full of water) then the soil and the roots in it stay at the temp of the frozen water (32 degrees). This is why you can stay warm in an igloo when it's 30 below zero outside - with all of that ice, the air around you stays at 32 degrees instead of dropping lower.
Our thermometer is reading 33 right now right next to the house. Too bad that's Fahrenheit not Celsius.
2 hours ago