What contributes to bud density?

I finished growing some plants that had pretty light airy buds on them, it was a purple widow. When I look at any of the weed from the dispensary its all pretty dense and bigger buds. Is it genetics that control this or is it from growing hydro or in supersoils?

IMO its a combo of getting plenty of light, and nutrients. yes genetics might have to do with size. but its more about optimum conditions. I grow in an area that only gets light from above, so the top nugs are nice and dense, but as you go to the bottom where they get less sun, more fluffy and airy buds.

The reasons the dispensary dope is hard ,dense and heavier than your airbuds are
1- grown under temps of 70- 80.
2- Indica not sativa
3- 1000w hps lighting
4- Quality medium and nutes.

I grow in a very hot room but I still manage to get good hard nugs. I use a product called Humbolt Countys Own G 10. It is a bud hardener that is only used in the last couple weeks and it works like a charm for me. Here is what it is. http://www.amazon.com/Humboldt-Countys-Own-Gravitation-Quart/dp/B00I3095HI/ref=sr_sp-btf_title_1_1?ie=UTF8&qid=1402512936&sr=8-1-fkmr1&keywords=mendocino+county's+own+gravity

Commercial growers often use CO2 therapy, keeping CO2 levels between 900 and 1200 PPM(Parts Per Million). This REALLY increases bud density but can be expensive. The truth is, potency of one strain varies very little between environments. Density is all about 'bag appeal'.

as mentioned, heat is a big reason a lot of folks get airy buds. heat, and harvesting too early, are the big two in my book...

If the genetic make up isn't there it won't happen no matter what. Lots of Sun and good food.

yea id say a lot goes to genetics too, i got some that always get rock hard no matter what and some that are less dense