One thing I've noticed is, that the lower the light intensity, the fluffier the buds. Likely, even if your main cola is rock-hard...the lower (secondary) buds are light and fluffy. (unless side-light is provided throughout flower)

Tried growing with 4' fluorescents a few years back, and all of the buds were very light and fluffy. I purchased a 400w HPS's and the same strain provides large, rock-hard buds that take forever to dry and cure. Same strain, (Swazi Skunk) same soil ,(Miracle Grow) and same ferts and micro's, same schedules.
Rusty Trichome Reviewed by Rusty Trichome on . How to get your buds nice and fluffy Instead of dry and brittle? Is there a specific way to cure/dry them for a more fluffy feel? or is it strain dependent? Rating: 5