Cannabis Flowering: When Does It Begin and What Are the Stages?

You’ve spent weeks coaxing your plants through the vegetative growth stage, and they’re finally beginning to show signs of budding. This is one of the most exciting parts of growing, and it’s important to be able to recognize the various stages of cannabis flowering and what you should do when. We’ll cover these questions:

1. When does the cannabis flowering stage begin?
2. How do you trigger the flowering stage?
3. Stages of flowering cannabis

Familiarizing yourself with flowering cannabis is useful whether you’re a novice or an experienced grower. The life cycle of a cannabis plant is fascinating. The basic life cycle of cannabis is comprised of four stages: Germination, cannabis seedling, vegetative, and flowering.

The vegetative stage is interesting as this is when your plant will grow the most. It’s also where you’ll hope to get all the problems out of the way as your crop recovers easily. During this time, she’s mainly growing leaves and stems, sometimes several inches a day.

The flowering stage, when cannabis plants begin to produce buds, is triggered by a reduction in light — outdoors, this happens when the sun starts to go down earlier in the day after the Summer Solstice. Flowering times will vary depending on your strain. Read on for more about flowering and what it stages look like!

Article originally published via our content partners at Homegrown Cannabis Co.

When does the cannabis flowering stage begin?

The cannabis flowering stage is when she develops those sticky resinous buds. This is where your hard work starts paying off.

With the exception of autoflowering seeds, the flowering stage begins once the plant hits a 12 hour light cycle. This means that it needs at least 12 consecutive hours of darkness per day.

Your flowers will naturally enter the cannabis flowering stage when grown outdoors. This usually happens when summer turns to fall and she receives less light daily.

Indoor growers need to trigger this phase by reducing the light to 12 hours daily.

The majority of strains flower in eight or nine weeks. Some sativas might take extra time.

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How do you trigger the flowering stage?

People say you shouldn’t rush beauty, but sometimes it’s necessary. Now that you know when to start flowering cannabis, let’s look at the how.

Trigger flowering in outdoor plants

As mentioned above, your plants will naturally enter the flowering stage. If, however, you need to harvest sooner — simulating darkness is your best option.

Put a blackout sheet over your plants or greenhouse for 12 hours every day. This will give your plants the impression that summer is coming to an end.

Trigger flowering in indoor plants

Your plants won’t naturally enter the cannabis flowering stage indoors.

They grow via artificial light instead of sunlight. To trigger flowering, you have to change the lighting schedule. Set it to at least 12 hours of darkness daily. Even though this is the norm, some strains might require more or less time in the dark—check with your breeder when buying your weed seeds.

As with most great things, there’s a catch.

Interruptions in the blackout time could delay cannabis flowering — or worse, if you’re not using feminized seeds, turn your lovely ladies into hermaphrodites.

Stages of flowering cannabis timeline 

Your flowering cannabis will go through three stages. These are further divided into weeks.

The cannabis flowering stages vary slightly depending on the strain. Indicas typically have short flowering times, around 8 weeks, whereas sativas can have long flowering times—up to 10 weeks, or even longer.

Early Cannabis Flowering

There is no abrupt change that signals the first signs of the flowering stage. Instead, your plants will continue stretching loads before they start blooming.

Make sure that your plant babies have sufficient space and nutrients during this time. Think of it as a teenage boy hitting a growth spurt.

Weeks 1-3 – Transition

Also known as the flowering stretch—you’ll notice a sudden increase in growth over these three weeks. Your plant needs to be big and strong enough to support the buds that’ll be growing over the next few weeks—it can double or even triple in size.

Your weed plants are still as resilient throughout the transition phase, making it easy to bounce back if something goes wrong.

The energy that would usually go into seed production is redirected to increasing the size and amount of buds; due to the absence of pollen from the flowering male cannabis plants.

You’ll start to notice loads of white pistils sprouting from your female plants. They usually accompany single leaf bunches at the top of what will later be the main colas.

If you spot pollen sacs on your plants, immediately remove them from your grow room as they are male plants.

Continue feeding your plants vegetative nutes during these few weeks. Your plants are still producing bud sites, so you can stunt growth if you introduce the incorrect minerals—meaning fewer and smaller bud sites.

If you still have space under the lights, you can gently bend the stems and spread them away from the center. This technique is known as low-stress training (LST). It helps to keep your canopy flat and ensures maximum light exposure.

Using LST at the start of the cannabis flowering stage, you can effectively increase your yield by as much as 40%.

Weeks 3-4 – Buds form

During this period, the growth spurt will start to slow down. Your weed plant should be about 50% bigger than a mere three weeks ago. All energy goes into forming the budlets instead.

By now, you can see actual buds forming, and the white pistils will look like they are shooting out of the budlets. You’ll also start smelling that characteristic dank odor around this time.

During weeks three and four, your plant should still be lush and green. If you notice a color change in the leaves, it could be one of two things. Discoloration and rapid loss of blades could indicate a nutrient deficiency. It’s easily treated with some nutrients if caught early enough.

On the other hand—if the tips of the leaves turn yellow/ brown or they look burned, this indicates nute burn. To treat this, you need to rinse out the excess nutrients with pH-balanced water. When left untreated, your plants will no longer be able to produce their own nutrients.

Don’t panic when the bottom blades turn yellow, or you lose a couple of leaves. This is normal due to the lack of sunshine reaching the bottom of the plant.

Mid-Flowering

When you reach this part of the cannabis flowering stage, training is no longer necessary. All your plant cares about now is the buds.

Weeks 4-6 – Buds swell

Next, in the cannabis flowering stages, you can expect the swelling of the budlets. They will fatten with each passing day. The buds will still have a bunch of white pistils shooting out in all directions.

Now that your plant is focusing more on fattening the buds, you can stop training. Instead, you have to start focusing on keeping the heavy buds upright.

If you notice your plants growing too close to the lights, super cropping is is a last-resort option. This means forcing your plants’ stems into a 90-degree angle. We don’t recommend it this late in the flowering stage as it stresses your plant out.

Experienced growers start looking into strategic defoliation for very leafy plants. It’s a great tactic as you expose the bud sites to the light, but keeping enough blades to carry your plant through till harvest is incredibly important.

Weeks 6-8 – Buds ripen

Your flowering cannabis has entered the next stage. The buds will start to ripen, and pistils will darken; how exciting.

At this point, you will no longer spot any vegetative growth. Your mature lady will devote all her energy to growing potent buds in her final stages of life.

It might sound strange, but now is the time to relax by caring for your cannabis plants.

She’s becoming much fussier regarding nutrients and much more sensitive to problems caused by them. Nitrogen, for example, isn’t being used as much by the plant, and if it accumulates in the leaves, it could lead to your plant self-pollinating, which is detrimental to the harvest.

As the flowering stage of a cannabis plant progresses, capitate-stalked trichomes dramatically increase in density. Interpreting the maturity of these trichomes is crucial because they produce the highest quantity of desirable cannabinoids and terpenes.

You might notice a phenomenon called ‘foxtailing’ during this flowering stage of cannabis. It’s when buds form on the bottom or sides of the existing ones. This is generally a sign of light or heat damage.

Other than foxtailing, over-exposure to heat and light could cause your buds to burn or bleach.

Late Cannabis Flowering

You’ve made it to the last stage of flowering cannabis. Soon your hard work will pay off.

Week 8+ – Flush and harvest

There are a few signs to look out for when you’re nearing harvest time. The strain you are growing will determine the specific week you can harvest, with a typical window of another 7 days.

With the odd exception, the pistils will usually turn orange nearing harvest time. Which means your plant is no longer creating new buds. At this stage of the cannabis flowering cycle, the trichomes will go from clear to amber as the THC levels increase.

Your plant is very sensitive during this cannabis flowering stage. Keep a close eye on your babies during these last few weeks to avoid bud rot and other ailments.

Your flowering buds will become heavy now, so be sure to provide ample support.

Now you’re getting ready for the harvest; it’s time to flush your cannabis plants. You’ll replace nutrients with pH-balanced water. Depending on the length of your cannabis flowering cycle, you should flush for a week or two before your planned harvest.

Your growing medium will also play a role in how long you’ll be flushing. Hydroponic growth mediums retain fewer cannabis nutrients than soil.

Think of flushing as your last chance to enhance the quality of your bud. 

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