The appropriate time to be concerned with bluer light in flower is at the beginning, during the 'stretch' period, when your plant will benefit the most from it. After about the second week in flower, when you see bud formation, that's the time to put the HPS bulb in, and keep it in until harvest. The MH light can help decrease stretch, but finishing under MH will yield fluffy and less massive buds.
stinkyattic Reviewed by stinkyattic on . 31 days flower HPS/MH ? Folks I am at day 31 flower. Jack Herer strain. I vegged with a 400 W MH then switched to 400 W HPS when I went to 12/12. I was wanting opinions on if it would matter if I switched back to the 400 W MH lamp just to give the buds a different light spectrum. I am 1/2 way through the flower cycle. I only have one ballast as its an interchangable. I went ahead and through the 400 W MH in just for the hell of it. I understand that it is better to use HPS for the flower cycle but just for Rating: 5