they sound like still basically seedlings, I think even 62 cm may be too close for a 600w hps. it wouldn't be heat, it would be light stress - if smaller plants get too much light, the chlorophyll goes into overdrive and burn the plant, no matter the temps. Especially if you are running 24/0 or 20/4.Hi all im growing sum himalayan gold, thay are 2 weeks old and seem very sensitive to heat?
Thay are 52cm under a 600wats hps, temp's are 70f 0r 21c, with a fan on them,
but im geting leaf curl and marginal leaf burn? has any of you had any simler prob's?
Thanks Ian Singerdale, thay are 42cm tall an 34cm wide, so not seedling? i have tried 3 thermometers an all the same, and thay are in 20 liter pots, but you are right as i have moved the light up sum more and thay are looking good today,they sound like still basically seedlings, I think even 62 cm may be too close for a 600w hps. it wouldn't be heat, it would be light stress - if smaller plants get too much light, the chlorophyll goes into overdrive and burn the plant, no matter the temps. Especially if you are running 24/0 or 20/4.
I'd think about raising the light more and seeing if that helps. Try somewhere around two and a half to three feet. It could also be that the pots are too small, or your thermometer may be broken / inaccurate. I've seen 10+ degree differences between different thermometers before. Just some things that come to mind.