frost covering?

can someone please clarify the purpose of watering then covering a plant before a frost? I assume you are increasing the water volume, therefor making it take longer to freeze. But the covering? Is that to keep heat in?

my theory: the extra water available forces the plant to use energy transporting the water. because the plant is moving the water around it has to get even colder to freeze - running water never freezes. also, the process of transporting the water takes energy, the consumption of which generates heat.

fact: the covering works because the ground radiates heat all night. usually this heat is lost to the atmosphere but you're catching it and keeping it near the plant. you are also keeping the air still, wind will strip away heat.






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It makes sense but if it's humid outside, won't covering it cause it to build mold? Sorry if the question is stupid, I'm a newb!

when it gets cold water vapor condenses on the plastic, lowering the humidity in the covered area. i would say that you're in danger of mold if you leave the cover on as the sun warms things up OR if you let the plant touch the wet plastic.





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well the odds are, if theres going to be frost, there will be no humidity seeing the temps will be far below the temps that create humidity

Good point.

exactly the info I wanted, thanks very much to all

7xstall, you are saying that the cover should be big enough that the plant isn't touching the inside? Or to be careful when removing it. This is a stupid question cause I could find the answer on google, but since you already know, is the condensation inside the plastic or outside?