How to know how much water to give plants

i have four 3 gallon pots with lowryders in the flowering stage. How much water should i be giving them. ex. quarter of a gallon each.

ALso what detertermines how much to give them. i know not to overwater and when to tell they need water again.

If you wait until the pot becomes dry and light as opposed to how much it weighed when you watered it, you cannot overwater it, so the amount of water is not that important. You should water a dry pot until water comes out of the drainage holes, even plenty of water. Water slowly, moistening all the soil uniformly, and don't water again until the pot is light again.

So what determines how much to give them is 'how much does it take to completely moisten the medium. It might not be exactly the same for a given pot volume, because the medium can vary on how much moisture it holds?

Give them water till it comes out the bottom drainage holes. I have been useing 32ozs of water for each plant and they are starting to drink a little fast cause they are getting bigger.32ozs=to red keg cups(beer pong cups).