For the boxes that are made to sit on the ground and are unable to be moved- you would water them just like you would any other plot of crops. Some of the designs that are made to sit on a patio or balcony, they have made smart designs that make watering really easy. Some have a spigot at the bottom that can be released to catch all of the extra water before it spills onto your patio. The wall design like we saw from Worth actually has an irrigation system so that all you have to do is turn on the water from your outside spout and it will water your plants for you.