I have 5 plants under a 400w MH (24/7) and they are all approximately 1ft in height. The light is hanging on a pully system about 8inches above them. They have been under the MH for 4 weeks now, when do you switch the light from the MH to the HPS and once the HPS is in, is it 12/12 light cycles?..and how close should the HPS light be to the plants? -2 plants are Sour Diesel and the other 3 are Bubble Berry Kush.
Depends on the strain, if it doesn't stretch much in flowering then I'd switch in the beginning of flower. If it does stretch alot then keep the MH for the first few weeks of flower to try to keep the plant as short as possible.
as lune said, i usually give em a week with the MH when i switch to 12/12, then its straight HPS till the end, i also give em a 10hr lights on/14hr lights off cycle during the last two weeks when flushing, then at the end of the run they get 48hrs of darkness before the chop/trim/dry. Alot of people use many different light cycles, light spectrums for flowering, just find one that you like and try to stick with it and learn the advantages/dissadvantages.
Sour D likes to stretch like a motherfucker, leave the MH in for a bit. Also be careful of light leaks, ECSD is very hermi prone if stressed at all. Sure is some good smoke though.
By the way, most people don't use different light cycles, most people bud under 12/12, because lots of other experienced people have allready done the work to figure out what light cycles work best. I personally would put it under the HPS when you put the light back to 12/12.