Usually a one foot pot is a three gallon. I use one quarter gallon to bud in. They are pleated and look like an acordian. I thought you said you wanted an extra two days in between watering. If your pots are that big I would water with a garden sprayer so the bottom never gets wet. Three gallon pots in my opinion should not get wet on the bottom unless the plant is over three feet tall and two feet wide at minimum.