If your attic floor is relatively level, you can save a lot of time watering (and prevent potential damage from leaks) by building a tray, flat-bottomed, with four-inch walls, that holds all the pots (if you can get it in there!--otherwise, use several smaller ones). Then you can water all the pots at once, simply by pouring water in the tray. The soil will soak it up by capillary action.
This should enable you to use one gallon pots. The pots will not limit the size of your plants, or the yield, because you cannot exhaust the capacity of a one gallon pot with a 400 watt light.
I know several people who always have 1/2 inch of water in their tray. They control the height with a float, which allows fertilized water from a tank to enter, replacing water as it is consumed or evaporates.
Generally, people say this is a crazy idea--but they are wrong! In an attic, humidity is frequently not a problem, because there is a lot of exposed wood around to act as a moisture sink. Furthermore, MJ is a riparian plant, growing naturally along creeks and streams, and in gullies, and is well-adapted to "wet feet". If you use a light soil-less mix, you will not suffer any negative effects--and you can take that to the bank! (I have, believe me).
This should enable you to use one gallon pots. The pots will not limit the size of your plants, or the yield, because you cannot exhaust the capacity of a one gallon pot with a 400 watt light.
I know several people who always have 1/2 inch of water in their tray. They control the height with a float, which allows fertilized water from a tank to enter, replacing water as it is consumed or evaporates.
Generally, people say this is a crazy idea--but they are wrong! In an attic, humidity is frequently not a problem, because there is a lot of exposed wood around to act as a moisture sink. Furthermore, MJ is a riparian plant, growing naturally along creeks and streams, and in gullies, and is well-adapted to "wet feet". If you use a light soil-less mix, you will not suffer any negative effects--and you can take that to the bank! (I have, believe me).