i have 4 nice plants 4 weeks into flowering and noticed the overnight low here in Oregon last night was 45 degrees. I have a 1000w hps indoors I could move them. Is this too much stress?
I think you could move them slowly. Try introducing it to them a little at a time.
does your ballast have a dimmer? with mine I have the option of 250, 500, 750 and 1000 watt setting as long as it has a 1000 watt bulb in it. keep us updated and drop us some pics
One other thing to consider is pests. Use caution always when bringing anything from outside to indoors. You can introduce bugs to already indoor plants. Just a consideration... Otherwise, go for it!
