All the time and hard work invested into medicinal crop doesn't pay off until the final weeks before the harvest date. While there is some variation from strain to strain in how and when the buds come to fruition, most growers find that medicinal nugs gain most of their mass and develop most oils and resins during the last two weeks of the crop's life cycle.
It easy to forget that everything leading up to fruition is also important. For example, building up the root system creates lush leaf and branch development, which is important for creating a nice cushion for the buds. In early flowering, the plant creates budding sites, which build on the structure you helped create through veg. During peak budding, the middle of the bloom phase is critical as well, because it's when the bud structures stack-up, determining whether you are going to be cutting down large tops or lots of “popcorn.”
During ripening -- the very late phase of budding -- a lot of the magic happens. Inexperienced growers may not know a well-ripened bud of cannabis when compared to one that “isn't growing anymore.” It's important to know the difference, because cutting down too early -- even if it's only by a week or 10 days -- can have an immense impact on final dry weights (as much as 30 percent in some instances) and can also derail the strength of the medicine, and alter the flavor profile.
Long story short: it may not look like the buds are doing much during the last couple of weeks, but know that they are quietly creating everything that makes marijuana magic.
How to Make Your Buds the Best They Can Be
During the final weeks, most strains are not taking in much external nutrients, so you should cut back on fertilizer and gradually switch to plain water, readying for the important “flush” that removes excess fertilizers from plant and soil (or growing medium) before harvesting. The flush is important: excess fertilizers left on buds can ruin a harvest with harsh tastes, diminished aromas and product that does not burn right.
Ripening cannabis plants redirect all the stored energy built-up through the life cycle, and creates a final push from the plant's own internal nutrients and chemical energy into the buds. Cannabis is typically an annual plant, so it has a genetic predisposition to “give it all” at the end. The incredible energy surge is directed at putting its “life savings” into the next generation.
Since you grew the crop for medicine and not seeds, the surge is focused on buds, which swell with resins, essential oils and terpenes, resulting in better harvest qualities and a greater dry weight. An ample dry weight is derived from the calyxes (empty seed pods) and resins -- those little bud leaves really don't weigh much by themselves when dry.
So, how do you know when the plant is ready to be harvested? The best way to determine maturity is to watch the resin glands. Use a magnifying glass to inspect the glands as they swell and become tipped in trichomes.
When immature, the resin gland appear clear; As they ripen they turn milky white; and as they begin to decline and degrade they turn amber. While it is the genetics that determine what the bulk bud's high will feel like, you can fine tune during harvest: Early maturity results in a heady high, while later maturity tends to be more physical.