Yup the strain helps. But the biggest hindrance to rock hard buds are growers. Too many additives, too much nutrients, overwatering, soggy roots, smothering their plants with love till the plants die.
Rock hard nugs? If you aren't using clones, start with a mother plant from seeds, selected from say 10 seedlings. Veg the mother for 6 months then take some cuttings. If you have clones, veg them until they are ready to flower rather than giving them the usual 3 weeks. Allowing your clones to form all the parts needed to support and deliver bigger buds is really the only real way. What hydroponic companies do is try to convince you that you can get the same results by jamming your plants with their products when all their products do is try to simulate the results of plants that have been vegged properly.
There are root stimulants to give your plants 700% increase in roots, there are stem thickeners, growth stimulators, bud enhancers and the list goes on.
Try this on your next grow of clones. Veg them for 4-6 weeks tipping and gently training them out to control the height so it doesnt get away on you. Wait till the main stem develops a wood like affect before thinking about switching. Everytime the lights come on, spray the leaves with an 1/8th strength nutrient to wake them up and put them into feeding. Water the pot only when the pot is light and water thoroughly. Watch the humidity levels. This slightly higher humidity is a sign that your plants are perspiring more, and is an indicator that it is using more and more of whats in the pot.
What this does is speed up the plants metabolism without using hormones....as well as giving it time for the root area to form properly. The roots in the end are the secret to big buds. As the plant matures and the stem thickens naturally, then switch to flowering.
Eventually you will see leaves forming so fast the plant cannot deliver enough nitrogen to them to keep up. This often gets confused with a deficiency, however most deficiencies stem from overwatering and over feeding.
The longest I have left a plant before switching was 4 months and it ended up being a monster. But so were the buds. Give them a chance to properly form all the adult parts and they will give you adult sized buds.
