. They are much more likely to drink a lot of water in the flowering stage. You didn't say in what medium you are growing in. If you are growing in dirt you can use water bulbs or other methods to water them. If you flush the night before you go, you should be fine for three days. I myself grow in bubbles. During veg i frequently can leave my reservoirs for 7 days without a refill and if i filled it i suppose i could leave it for ten days, but id be nervous.
During flower my plants can drain 2-3 gallons in a day! I water the last few weeks, every other day. No way would i leave for more than 3! Plumbing stores sell all you need for an auto filling Device you can use to keep a res filled. Think the floater in your toilet. Floater rises with level and shuts off valve.
If you are in dirt (i used to be) its a bit easier. A week on the glass bulb is fine. A 2 liter with pinholes in the bottom will let out a very slow amount as well so as not to overwater. Dont apply any nutes or a very small amount right before you go. If your plant starts wilting you won't be there to help!