Marijuana literally grows like a weed. If you pop a seed, give it the proper light, air quality, and nutrients, it will grow robustly up toward the sky. This is generally a good thing, but if you are trying to create a final product that is high-quality, dense, and free of extra leaf and whispiness, then a certain amount of “containment” is required. This means that the weedy aspect of the Cannabis plant needs to be slowed down and controlled to allow robust root development, sturdy branches, and a lower, more compact plant to form.
When the plant begins to flower in this contained state, it is not stretching away from the root ball as much, can harness the light source more effectively, and the flowers- or buds- become dense, large, and healthy. This is preferable to the root ball energy being spread out to long stringy branches which generally creates “popcorn buds” (small whispy buds that are difficult to trim.)
The techniques for containment are recognizing the ebb and flow of plant growth and knowing when to trim leaves and branches back so that others can receive more energy. It is another argument for learning to grow in a hands-on way from a grow consultant like myself.