depends on plants position. i've found pot to be more hardy in terms of water than i expected. depends on age of plant, ive found the younger the plant- the more 'moisture' it needs(must have something to do with root development). i put my finger an inch or so into the dirt near the roots. if its not moist down there it needs watering. plenty of mulch ( old lawn clippings are great as they also feed your girls) will help alot in keeping your plants nice'n' moist all day and all night. ive found its better to under water than water too much.
i have a lil irrigation set up but i think i'll set up a drip system this year.
help the planet- conserve the H2o.