This tutorial is meant to explain how a cannabis plant usually develops when grown indoors, since that is done under controlled conditions, and plants tend to grow the same way. For the purposes of this tutorial, the flowering stage starts the day you switch to 12/12. Autoflowering strains of cannabis don’t need special light periods to start flowering, however the cannabis flowering timeline in this tutorial is a good general guideline for indoor auto-flowering strains, too.
Their “vegetative stage” lasts about 3-4 weeks, so as long as you start counting at week 3-4 from seed (when they start getting their first pistils) this flowering timeline will generally apply to autos too, though sometimes they finish up faster. During the first few weeks after being switched to a 12/12 schedule, your plant will be growing like crazy and rapidly gaining height. In fact, a cannabis plant can (and frequently will) almost double in height after the switch to 12/12. This period of super-fast and often stretchy growth is sometimes referred to as the “flowering stretch.” Example of flowering stretch – what to expect. Although your female plants will start sprouting lots of white pistils, they usually won’t start growing “real” buds with substance quite yet. If you’re new to growing cannabis, it’s very important to note that only female cannabis plants make buds. Did you know you can figure out if a plant is male or female while it’s still in the vegetative stage? If your plant is male, it will start growing distinct pollen sacs and should be removed from the grow room immediately to prevent it from pollinating your female plants and causing ‘seedy’ buds.
Learn where to get feminized (all-female) seeds online so you don’t have to worry about male plants. Remove any plants growing pollen sacs instead of pistils, because they are male and won’t make buds. Plus they can pollinate your female plants and cause them to grow seeds! What if my plant is growing both pistils and pollen sacs? Female plants should be growing pistils wherever a fan leaf meets a main stem. They look like white wispy hairs emerging from the joints. During the first few weeks of the flowering stage, you will see bunches of single leaves forming at the tops of your main colas (like in this pic). Soon white pistils will start coming out of the middle of the bunches, and they will become your main buds! During week 1-3 of the flowering stage, your plant will mostly be producing new stems and leaves as it grows taller. Right now your plant is still very resilient and can handle problems just like in the vegetative stage. However, it’s still very important to avoid problems and take great care of your plant! As part of the stretch, your plant will be growing out its bud sites. Stunting growth at this point could cause the plant to make smaller and fewer bud sites than it would if it were healthy and growing fast. If you have more room in your grow space under the light to spread your plants out, or if you are running out of headroom, it is important to gently bend stretching stems down and away from the center of the plant to help maintain a flat canopy (a technique known as low stress training). During the stretch, gently bend new stems down to try to maintain a flat, even canopy. If you keep up with it during the stretch, you can prevent any one stem from getting much taller than the others. When stems are new, they are flexible and easy to bend, but they quickly harden up and turn woody. By keeping a close eye on your plant and bending any too-tall branches down and away from the center of the plant as soon as you can, you will maximize your yields since that flat shape will most efficiently use your grow lights. If all your main bud sites are spread out and about the same height, you can increase your yields by up to 40% or more! Spreading out your bud sites and maintaining a flat canopy can increase cannabis yields by as much as 40%…or even more! At this point, you only have a few weeks left until you lose the ability to do any further training, so don’t miss this last opportunity to control the shape of your plant, especially if you’re running out of room! The mad stretching of the first few weeks will start to slow down in week 3-4, but your cannabis plant will still be growing upward. At this point you’ll actually start to see real buds instead of just hairs (I like to call them “budlets” during this stage) and all the pistils will be white and sticking almost straight out. “Budlets” start forming where buds will be, with white pistils sticking straight out. Your plant is going to start getting a little picky about the environment and nutrients in week 3-4 so it’s important to keep a close eye on your garden. You need to make sure your plant stays healthy all the way to the end of the flowering stage, and you’ve still got more than a month to go so you don’t want your plant to run into any major health problems now! Be especially aware of leaf symptoms, for example: discolored/yellow leaves, or if your plant starts rapidly losing leaves.
It’s completely normal to lose a few leaves at this stage, especially leaves that aren’t getting light (which often look like they may have a nutrient deficiency and then fall off, but it’s just your plant cannibalizing the leaf since it isn’t getting any more light). That being said, overall your entire plant should still be lush and green in week 3-4 while your budlets are forming. As your plant continues through the flowering stage, it’s normal to see a few yellow or discolored leaves near the bottom of the plant, especially in the places where the leaves are no longer getting light. This isn’t anything to worry about if it’s just a few leaves as the plant is putting its energy to the top of the plant and the buds. But it’s not normal for your plant to be yellowing or losing leaves rapidly like this. This is what happens when you give your plants too-high levels of nutrients – the tips of all the leaves actually get “burned.” While a little bit of nutrient burn won’t hurt your plant, it’s important to try to avoid it if you can. Your plant can never recover the parts of the leaves lost to nutrient burn, so if you accidentally give too much nutrients in the future, the burning will start “climbing” up the “fingers” of the leaves.
Cannabis leaves tend to look much less appealing/pretty as more of each leaf gets burned. However, even cannabis plants with severe nutrient burn can produce good bud, so don’t give up if you run into thi problem! Try your best to avoid nutrient burn (burnt leaf tips caused by too-high levels of nutrients), as it can only get worse as the flowering stage continues. When nutrient burn starts getting bad, it can actually start discoloring your sugar leaves (the small single-finger leaves emerging from your buds).