Flowering Week 1-2
A few days after the light switch, your plant will experience a burst of vegetative growth for up to two more weeks, with most plants increasing 50−100% of their current height during this time. If needed, apply the low stress training techniques outlined in the previous section to control the plant’s overall height. Once your plant has finished this “final stretch”, it will focus its energy on flowering, creating buds or pollen sacs, and completely stops all stem and leaf growth for the rest of its life cycle.
This is also the time to swap your grow fertilizer with a phosphorus-rich bloom fertilizer which will help the flowers develop faster and larger.
Flowering Week 2-3
Your plant will begin to form its reproductive organs that will differ depending on its sex. Female plants will create pistils — white hairs that will group near the large fan leaves as well as at the ends of each stem. These will grow larger over time, developing into fat buds. Male plants will create pollen sacs – used to pollinate female flowers when they develop and open up. Unless you are trying to create seeds, any identified male plants must be removed as soon as possible before the pollen sacs have enough time to fully develop.
As each patch of buds bulk up and continue to grow, trichomes will begin to form and be accompanied by the strong odor hemp is known for. Trichomes are your plant’s defense mechanism that deters wildlife from eating it and is where the major cannabinoids such as cannabidiol (CBD) is located. Through a jeweler’s loupe, they will initially look like clear and spherical dots, and as they develop the dots will be followed by a clear stem, giving it an appearance similar to that of a crystal mushroom.
Flowering Week 3-8
The buds will continue to bulk up as the white pistils shrivel up and turn darker in color. Looking through a jeweler’s loupe, the trichomes will slowly transform from crystal clear to cloudy white in color over time.
The buds are at their highest potency when the trichomes have mostly turned cloudy white, taking place towards the latter half of this time frame for most strains. If the plant is not harvested at this point, the CBD content of the plant will start to drop by around 5% in potency every week. Note that most growers will choose not to harvest at the highest potency because at its peak potency, a plant can still grow significantly larger each week for another 2-6 weeks before slowing down in growth, making the trade-off between potency to yield worth the additional wait time.
Flowering Week 8-12+
At this point in the flowering stage, most strains’ buds will slow down in growth as most, if not all, of their white pistils shrivel up. A close-up look at the trichomes will also show some starting to turn amber, a clear sign that potency is rapidly degrading. This is the latest you will want to harvest your plant because, after this point, its potency will continue to decrease with no increase in harvest yields to compensate for it.