Genetics, strain, and LIGHT! I want COB style DIY but until I can afford to invest that money I'm buying used MH/HID fixtures and new bulbs to get started. Another KEY ingredient is knowledge AND Experience, you can find that here @ GWE by using the tutorials available here. The search function works great ! I just searched Getting larger more dense buds and this popped up first.
http://www.growweedeasy.com/dense-buds
Top 5 Most Common Reasons for Airy Marijuana Buds
(get a complete breakdown of all the ways to increase bud density in the article below)
Light - The most common reason buds don't develop as densely as they could is the plant didn't get enough light in the flowering stage. Although cannabis can survive in relatively low light levels, it won't produce much bud. Up to a point, more light in the flowering stage = bigger buds. On the flip side, too-bright light (less common, but can happen when buds are too close to grow lights) can also cause buds to develop poorly and/or produce airy, hairy fox-tails.
Strain / Genetics - Some strains will only produce airy buds no matter what you do. For example Sativa plants often grow buds that are less dense, while Indica buds tend to grow more compact. Although one style isn't necessarily better than the other, if you want dense buds it's important to start with genetics that come from a plant that grows dense buds.
Temperature - Cannabis wants the temperature just right for optimal bud growth, which is about the same temperature as what's comfortable for humans. Too hot temps in the flowering stage (especially above 85°F/30°C) can cause plants to develop loose buds, and can also cause buds to herm and become seedy.
Nutrients - Buds won’t fatten and get dense unless they're getting the right nutrients at the right time, which means low Nitrogen (N) and plenty of Phosphorus (P) and Potassium (K) in the flowering stage. Giving too much Nitrogen (found in all-purpose plant food) in the flowering stage results in smaller, looser buds. Learn more about nutrient ratios. Other nutrient problems and deficiencies can also negatively affect your bud development if left unchecked. However, the most common reason growers see nutrient problems hurt development in the flowering stage is incorrect pH at the plant roots.
Airflow & Bud Spacing - Poor airflow around buds and lack of strong, direct light will prevent those buds from developing as densely as they could. Buds need a little space to themselves in order to get big and dense, and won't fatten up if they're not directly exposed to fresh air and strong light. In the wild cannabis is a wind-pollinated plant, so it only spends energy growing and fattening buds that are exposed to a breeze and the sun. To make sure the buds are getting a breeze, each big cola on your plant should have a few inches of space around it that it's not sharing with leaves or other buds.
Never grow loose, airy buds again!
These buds are fluffy and airy - not dense at all. This tutorial will show you how to make your cannabis buds grow compact and dense every time!
6 More Tactics to Increase Bud Density
In addition to fixing the problems stated above, here's a complete breakdown of additional tactics to increase bud density (more complete info in the article below or click the links)
Reduce humidity below 45% RH during last 2-3 weeks before harvest - Lowering the humidity towards the end of the flowering stage triggers a natural plant response that can make buds more dense as well as increase resin production
Density Boosting Supplements - There are two main classes of bloom-boosters. The first class focuses on enhancing plant processes, and uses dozens of various ingredients like amino acids and trace minerals. The second class works by increasing Phosphorus/Potassium levels directly. Some growers also use Blackstrap molasses in order to accomplish many of the same goals without needing a special plant supplement.
Don't harvest too early! Harvesting too early will prevent your buds from finishing up. They gain a lot of weight and density during the last few weeks before harvest, and you're hindering all your hard work by not waiting just a little longer.
Dry & Cure Your Buds - In addition to improving taste, smell and potency, drying and curing your buds the right way will cause them to "tighten up" a bit. If you dry your buds too quickly or don't cure them in glass jars, you're missing out on almost 50% of what's going to determine your final bud quality!
Don't overwater your plants - it's boring but true! Not much to say about this, but don't overlook this common issue and make sure to water your plants right. If your plants leaves are droopy, it means you could be missing out on better growth!
Get a Big Enough Container - If your container is too small your plant just won't be able to support bigger, denser buds no matter what else you do. Make sure to get the right size container and if possible, get a "smart pot" or "air pot" as they prevent overwatering, increase growth and support larger plants!
Continue reading to learn more in depth about these tactics and techniques to boost buds density!
http://www.growweedeasy.com/dense-buds