Leaf tips just began to curl down last 1-2 days on 3 out of 5 girls. Mainly at top and midway. Growth has been great. Some curled tips have light green or yellow color. The plant in the distance in the middle pic had a cal-mag issue so lower leaves are discolored. Only plant that had this issue, fed cal-mag about 5 days ago, not getting worse or better. FFOF soil in 1 quart pot for 16 days, then transplanted into 4 gallons with FFOF. These are on day 33(day 1 beginning when germinated seed was put in soil). So I have yet to feed FoxFarm nutes. Only fed pHed water, always allowed pots to dry out good before watering. Not a water issue not a pH issue. Temps are 80 day/70 night with 400 watt mh. Averaging 50% humidity. Used T5s first 10 days. After transplant I switched mh to dim at 250 watt for 48 hours. On 18/6 schedule. Plenty of airflow, clean grow room, not a heat or humidity issue. No bugs. Do I need to feed? Only thing I can think of. I've heard FFOF feds anywhere from 2 weeks to 5 weeks so that's not really clear. Definitely a little yellow beginning to show on a few of em. So feed time? Any help appreciated.
Yes feed time. They are at very least Phosphorus deficient. Whole-plant pics are needed for a complete diagnosis.