I agree with most of what everyone is saying. I'm flowering right now and the buds are rock hard also. They also have that "dank" smell. My buds are so potent that I get high off the smell
The tricks I used were: get the lights as close as possible. Use molasses and water (1 table spoon per gallon), every second watering, during veg and flowering. The nutes I use for flowering are 1 30 20, I also used CO2 during flowering. For every jug of nutes or molasses and water I mixed, I added vitamins. Believe it or not, you can make your own liquid vitz. All you have to do is take a few multivitamins and run cold water over them to wear off the coating. Let them dry for a few hours and grind them up using a electric coffee grinder so it's the consistency of talcum powder. Mix the power with RO water (slightly acidic) and put it into some kind of container so you can add drops of your solution to your water. I tried this solution on 2 of 4 plants when flowering. The plants I used the vits on had bigger buds.
Also I used a 75w red flood light to add more of the red light spectrum. One trick that really helped for me was to bend the branches so the top of the plant had equal light. I am only using 3 23w and 2 42w cfl and 2 T8 flo tubes (2700k), also the 75w flood light. All this seems to work pretty dam good so far, just takes a bit longer. One of my plants yielded 7 ounces of dry bud. Replicating nature as best as possible, is the key. Don't have all your lights go off at the same time, maybe have the red flood light on for the last half an hour to replicate the sun going down. Hope this helps someone!