I guess after 3 weeks it would be fine. Maybe let them veg another while under the HPS.

Try to keep the nodes at 1 inch apart, so keep the light close enough to prevent stretching but not too close as to burn.

I normally wait until the plants are about 12 - 18 inches tall before flowering. But that is entirely up to you and your grow area.

Maybe you could post some pictures.
silent leprechaun Reviewed by silent leprechaun on . CFL or HPS? Hi guys This is my 1st grow. Im currently using 1x 60w cfl for my seedlings. They have grown pretty well in my tent . I was wondering when will it be a good time to start using my 600w hps. My temp average is about 78f and 50-55 humidity. Things are going well, i was thinking of leaving the 160cfl for another week and then putt the 600w on but far from my plants. Its been about 3 weeks since iv germinated them from seed (wet papertowel method) and they have grown well i guess. Green and Rating: 5