Many Indicas are known for really thick and dense buds, even Indica/Sativa hybrids with Indica dominant bud structure. Basically get a strain like an Afghan, a Kush, or a Nepalese Hash Plant. Using 'bud builders' on plant's that already have some of these characteristics can help you make thier buds even bigger. So I would start with the seeds of a hash-producing indica instead of something like a haze, if big tight buds are what you want.
then during flowering make sure it gets something with low N, like 5 or under. Nitrogen promotes taller plant growth and vigorous new growth (we dont care about that in flowering... Veg period is over!).
High P is good for creating bigger thicker buds than your variety would normally have. This is because phosphorus helps plants capture light during photosynthesis. look for 20 or above. Since the light will not be going toward new growing parts of the plant (your lower nitrogen levels will curtail that), it concentrates on the flowers it has created, helping to make the bud grow by adding more leaf mass to it.
Your K number should be relatively high, but not as high as your P number. Potassium is important to plants in all stages of growth. A K number of 10 is ok for flowering. It helps the plant fight diseases, it helps the stem stay strong even when nitrogen is cut back. It also helps plants open and close stomatas (think thats spelled right). Basically all the calyxs are covered with resin glands that, over the course of the last few weeks of flowering, open up and produce little trichomes of resin. I think the resin glands are composed of cells, and as the stomatas on these cell walls open up, THC is forced out of the gland. It happens slowly, and the THC is not runny or gooey or drippy, instead as each new bit gets added on to the pottom, they get taller, kind of like a stalagmite. Eventually they look like the little alien antennas we so love looking at under our 420 scopes.
This, I believe, Is a pretty decent answer to your question. I'm just a novice though, I'm sure someone with more knowledge than I could speak up. And Fdd2Blk, I think he also wants to know a little of the science behind which parts of the nutrients contribute to which parts of the flowering, and why. Not just, 'Which is the best brand?'.
No offence intended, I hope none is taken, but I would find it interesting if someone with as much knowledge as you would cover this subject as I tried to. That would be fuckin' sweet. I know it's not exactly the question he asked, but I think it will help heim, and all of us, understand at least what NPK numbers are appropriate for flowering and why they work the way they do? or did I do an ok job?
I want to add a disclaimer. I am not a scientist. This is just how I understand it to work, and some of my own ideas using common sense combined with what I know. I may not be a hundred percent correct... but I am right alot of the time.
Keep on giving good advice, because you always do.
