Cotyledons, so you top at the first set of TRUE leaves. ALL plants have a form of cotyledons, or embryonic leaves.
I lower my lights towards the plants instead of having them on different levels/platforms. This way they are stable and wont knock each other or themselves over. Sometimes I get even crueler and make THEM stretch to the light. Like we learnt from lime, its a damn resistant, resiliant 'weed' we have...it grows for me...im not its slave.
I cant even be bothered using aluminium foil or white paint in my cupboard...when do we see reels of al foil being dropped from the heavens to surround plants outdoors? Whats the percentage of light increased anyway? <~ 5% ? So the increase of growth I will see will take 20 days to see 1 days extra growth, for a 70 day strain, I'm seeing 3 days extra growth over the whole time period...not worth the hassle nor the money for increasing light reflectivity. Though I do make hoods for my CFL's so they reflect any direction other than upwards, I believe this increases the light / use capacity.
Sorry for thread jacking or just talking shit.
Was kind of relevant