Once between the beginning of Flower and the 3-week mark. 3 weeks after beginning flower is the last time you'll want to defoliate.
You can remove fan leaves during flowering in much the same way you do during veg. Prune away large leaves that are overshadowing bud sites, as well as dead or dying fan leaves. One thing to keep in mind is that you should prune in intervals, giving at least a couple weeks between each session.
When you're completing your late-flower (week seven) defoliation, you can go ahead and get rid of every fan leaf. If at any point you look at your plant and think “oh no, I took off too many fan leaves,” don't worry.
In weeks 6-8, the buds of your plants will begin to harden; the delicate trichome heads of your flowers will cloud and turn amber, and the once milky pistils of your buds will shrink, turn brown and become fragile. Also, as your plants continue to ripen, new aromas, flavors, and pigmentation will develop.
Weeks 4-6: Buds Fatten Up
At this stage of cannabis flowering, your buds are getting bigger. They'll still have all the white pistils sticking out, but you'll be able to see the buds getting bigger every day.
If you can wait, you'll see that buds bulk up noticeably in the last couple weeks before they finish growing. Give the plants only water—no nutrients—after you see the buds are mature. Hold off on picking them for another 10 to 14 days, when they'll be at their peak.
If you grow strains with an average flowering time, the majority of bud development will occur by the 6th week of bloom. In the last two weeks, the buds will mostly be ripening and not really growing much more in size. At this point, the previously white pistils on the buds will now slowly turn amber-brown.
To some degree, more light translates to fatter buds and higher yields (you'll need to pay attention to the distance between your grow light and plants or your plant may suffer from light burn). Increasing light intensity is the most effective way to fatten up buds.
Late flowering / Ripening stage – week 6 to harvest
They are sticky to the touch and can be very smelly. You are very close to reaching your goal = harvesting! Most importantly, buds are now covered in trichomes, which are rich glandules for secreting THC and other cannabinoids.
If many of the trichomes you see are still clear and transparent, it means it's still too early for harvest. But when most of the trichomes have an amber colour and an opaque clarity, this means that the THC content of the buds is at its maximum and the plant is ready for harvest.
Because trimming stresses the plant, you need to be mindful of how much your are defoliating. If you defoliate too much at once, you can stunt or herm the plant.
By cutting off the leaves on the calyx and bottom, the plant can focus its energy on the buds, which can avoid the formation of florets (the ones that are thrown away at the end). The goal of this defoliation is to produce more high quality, dense and uniform buds.
During the seventh and eighth week of marijuana flowering, the buds finish forming, increase their weight and density, most of the pistils wither, and many of the trichomes change color, going from transparent to white or from white to reddish or amber All these changes are symptoms that announce that the harvest of ...
Whether you are removing fan leaves during the vegetative or flowering stages, it is important not to remove too many leaves at one time. Defoliating is a sensitive process, and if it is not done properly, the removal of the leaves can shock the plant, trigger early flowering, and produce a less impressive yield.
Removing a few fan leaves is one way to begin exposing bud sites that would otherwise be unusable flower. If you remove the light-blocking fan leaves above however, these larfy bud sites could end up being popcorn nugs, so decide based on the amount of air and light you are allowing into that section of the plant.
Plants have to spend energy growing leaves, stalks and buds. By trimming off the unnecessary leaves, more energy is left to put towards bud growth. Additionally, every time a bud site is pruned, two more will be created to take its place – leading to more buds on a single plant.
Around week 8 of the flowering stage, buds will start fattening quickly. You'll see that trichomes and pistils are maturing and changing colors. Usually, when trichomes turn from transparent to a milky/whiteish color (and maybe 5-10% of them turn amber), your plant is ready for harvesting.
In the last two weeks, the buds will mostly be ripening and not really growing much more in size. At this point, the previously white pistils on the buds will now slowly turn amber-brown.
At the absolute minimum, you should wait until 50% of the trichomes are cloudy and 50% of the hairs have changed color. Again — do not harvest if fewer than 50% of the trichomes have turned milky. And do not harvest if fewer than 50% of the pistils have turned brown/orange.
In order to get more potency in the flowering stage, you want to inspire your plant to produce more resin-producing trichomes. You do this by cranking up blue, white, and UVB lights to 100% and backing red down to around 50%.
Topping to increase the number of colas
Topping is a form of pruning and involves pruning off the branch tip of the main cola. When you top the main cola, the energy goes to the side branches. The next two lateral branches will become the main branches. Topping will increase the overall yield of your grow.
Week 5 – Trichomes begin to ripen
At the halfway point of the flowering stage, your plants should be displaying easily recognizable buds with a good number of white pistils, though a few may have started to turn a brownish orange. Trichome covered buds will also begin to form along the main cola.
Cannabis plants need water and nutrients to grow and develop big, healthy flowers. Drought, overwatering, and over/underfeeding can all affect your plant's ability to develop big, dense, and heavy flowers.
Over the years, the rate of these active compounds has risen. In 1994, variations of the plant contained about 4% of THC. Today, these amounts have spiked. According to a study published by the National Library of Medicine, the drug's potency has tripled.