Jeans and a nice shirt. It’s a pretty laid back place clothing wise. No ripped jeans, no open toe shoes, no cropped tops.
They are interested in your knowledge about cannabis even if through personal experience, the more the better. It is not a trick question to be asked if you smoke cannabis. They want to you if you are efficient, independent and willing to take on a lot of overtime hours. Maturity seems to not be an concern, they want laborers who listen and follow.