Ok your plants need some help. I’d say they got a N and Mg def. for sure. And probably some others

Get some organic fish emulsion and give it to them 75% strength ASAP.

Any N/Mg source will do the trick. I just like to use fish em. Because it’s very gentle on them yet acts quickly. And it’s very hard to do harm with it. It also is source of a lot of other important things.

You can use Bio grow (I don’t know what it is) but only feed at ΒΌ strength. You don’t want to stress them out.

Oh the bright side. Your plants are very big for 3 weeks old IMO. The numbers you posted look good so they probably just grew too fast. IF you can Use the fish em. It’s only 7$ got a jug and you’ll see the difference within 24 hours.

You can also treat them with Epsom salts to get ride of the mg DEF. I cant remember how much to mix but I know you can find it on this site.

Good luck. Treat them, and post some pics in a day or two. If they change quickly for the better we know we got the problem. If not, we’ll try again. So if I’m wrong using fish emulsion wont do any harm, I cant say the same for a synthetic fertilizer.

Harris
harris7 Reviewed by harris7 on . Help ! Leaftips going brown and turning up ? PH 6.5 Temp 80 ,400w MH .Plants are 3 weeks old , i havent feed them anything only water as it says on the soil no need to feed for 4 to 6 weeks. Is it time to feed them ? :confused: Rating: 5