flip that leaf over and check out its underside with a magnifir and see what you can see. also, we need EVERY detail of your grow. What are the conditions? What soil? How much water? How often? Which ferts? How much? How often? etc...
I`m using 250w HPS Shultz ferts 10 15 10 Ventilation is from PC COOLER ;] Temperature is 27c I`m Growing this stuff in terrarium I think that my soil is acided :/ can it be?
Shultz Liquid Plant food 10-15-10 (7 drops per quart) can be used every watering so its not nutrient burn... Looks like heat from light to me.
DierWolf these defects was when i grow with 130w CFL so i think that it can`t be burned :/ . i`m using the peat, and I heard on the grapevine that the peat is acidic.
Your lights are WAY too close... the plants are getting burnt... move the light away from the plants. a 250W hps puts out a lot of heat, and will pretty much cook your plants
the distance you should keep your light is determined as follows: Put your hand under the light at the level of your plants' canopy. Raise the light (or lower) until it is where you can keep your hand under it for 60 seconds without any discomfort. Whatever distance this is, is the MINIMUM distance from your light to the top of your plants.
Ok man. All this talk about acidic soil and no mention of your ph. Just curious, what is the soil's PH? Guess it doesn't matter now that you solved it but, just curious. On a 250 watt HPS I would go 25-40 cm away from tops. Sorry I am late to this one.
Agree with both of these, I believe the technique from Up4Anything will result in the distance SmknVTEC recommends. Yo, for the Americans, that 25-40cm is about 10-16 inches. The other recco of 60-90cm (24-36 inches) sounds too far away but whatever distance results from the back-of-the-hand test.