Only time ive seen airy buds that were not genetic was an indoor inner west Sydney grow were the temps in the grow room were consistently over 40c (104F) (a unit grow in Ashfield for those that know Sydney). So yes I agree heat does cause airy buds, may cause stretching etc. But due to me coming from being predominantly an outdoor grower you just adapt. Ya have to accept what the environment is and grow.
I think I read somewhere that the plant can regulate its leaf temp to 18c?? Please don't quote me and can handle quiet large temp swings and still do this. Guessing mainly through Transpiration. Hence the importance to being close to the charts on that.
This may be the same bud as earlier (next to the bic lighter...) or another one (it was a Scrog so lots this size.) check out the weight. I don't consider that airy? Not saying its huge or Cricket ball dense...But its decent.
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I hope I'm not coming across as argumentive or anything and If I am I apologise. Id love a nice set up like you have. Just some of us have to deal with what we have and sometimes I think the more professional growers forget that it can be done, and done pretty well with less.
As long as I get a harvest and don't get busted I'm usually pretty happy!