the use of a fan will tuffin the stems, i use a fan, but i also massage all stems, what i mean by that is, i take each stem, and branch, and bend it back and forth, all the way up and down the entire stem/ branch. i do that daily for about a week, at that time, they should all be alot stronger. i also do the same process during the 4th week, the reason for that is, nitrogen builds up in the stems, about the 4th week the plant needs very lil nitrogen, by massaging the stems, it dislodges some of the nitroget that was kinda stuck in the stems. this will alow the inside of the stems to transfer more nutreints to the budding plant.