stress makes plants produce alot of crystals, but too much stress and the plant will go hermie, ive heard of ppl clipping of leaf tips to trick the plant into thinking its being eaten, then it covers itself in resin, so bugs cant eat it...

i give mine irregular photoperiods, and let the soil dry right out before i water it to make it produce good amounts resin... on the last week, i flush it, and then leave it to dry out till harvest, and when its bone dry, i harvest

good luck