Question

Often times farmers will spray their crops with water when freezing temperatures are predicted. Why is this a common practice?"

Answer 1

Because cold air will have to take away a lot of heat to freeze the water before it can start cooling down the crop below 0°C.

Then the ice might shield the crop from the frost bite.

Answer 2

So after the water get frozen, it makes a layer on the crop that work as a shield from the lowet temperatures?
A layer of ice insulate the crop?
That's the idea?

Answer 3

That's the secondary effect. The main effect is that the freezing of water releases heat.