What is the equivalent to one inch of rainfall?

My daughter is participating in a 3rd grade cabbage growing program for a $1000 scholarship. According to the directions, the cabbage needs at least 1" of rainfall/water each week. 1" measured in what? I've grown plants all of my life and a few vegetables, but I've always gone by the "feel" of things. There was never $1000 riding on it! :o) Any ideas?

What is the equivalent to one inch of rainfall?
The water it needs will be 1 inch(=2.54centimeter, cm) times the planting area. If the cabbage is planted in a pot of, let's say 0.1 square meter(=1000 square centimeter). Then the amount/volume of water it needs is 1 inch times the planting area:


2.54cm*1000 square cm = 2540 ml =2.5 liter per week


So just go by the approximate planting area.
Reply:It's the same measurement used per week for lawns. The only way to tell is with a rain gauge. Maybe you should consider purchasing a moisture probe. They sell them in home centers. You just stick it in the soil and it measures the moisture in the soil. If you have other plants it will come in handy as well. Takes the guessing out of watering.
Reply:if its in a pot,one inch is from the top of the soil,if its a small pot i would pour about 1/4 inch in every other day...are you aloud to use miracle grow? if so, do it...and dont be afraid to use to much, wont hurt anything...

gina