Flowering marijuana: all about the flowering phase

All about flowering marijuana

Everything you need to know about the flowering phase of the cannabis plant

If you have decided to open this article, it means that you too, would like to understand what happens in the flowering phase of cannabis, right?

This is the time when the harvest will bear fruit, which is why an experienced and licensed grower must pay attention to a few factors.

Which ones?

To answer this question, in this article, we will delve into one of the four growth phases of the plant for information purposes only.

Let’s begin!

When does the flowering phase of cannabis begin

When does the flowering phase of cannabis begin?

The flowering phase of marijuana is when the resinous, sticky buds develop and when the hard work of the cannabis growers begins to pay off.

Except for auto-flowering seeds, the flowering phase begins when the plant reaches a twelve-hour light cycle, meaning it needs at least twelve consecutive hours of darkness per day.

The flowers will naturally enter the flowering phase when grown outdoors. This usually occurs when summer turns into autumn, and the plant receives less light daily.

On the other hand, indoor growers must trigger this phase by reducing the light from sixteen to twelve hours per day.

Most varieties flower in eight or nine weeks, although some sativas may take a little longer.

But let’s delve into this phase by phase.

Phase one: early flowering

There is no abrupt change highlighting the first signs of the flowering phase. On the contrary, the plants will continue to elongate before they flower.

In this phase, the small plants must have enough space and food.

Weeks 1-3 : Transition

In these three weeks, you may notice a sudden increase in cannabis growth. The plant needs to be large and robust enough to support the buds that will grow over the next few weeks: keep in mind that they can double or even triple in size.

During the transition phase, the plants are still very hardy, so it is easy to recover if something should go wrong.

Energy usually used for seed production is redirected to increase the size and quantity of buds due to the absence of pollen from flowering male cannabis plants.

In females, on the other hand, lots of white pistils will begin to sprout, usually accompanying clusters of single leaves on top of what will then be the main colas.

At this stage, it is essential to feed the plants correctly: if the wrong minerals are introduced, there is a risk of stunted growth, which means fewer and smaller buds.

If a grower knows that he still has room under the lights, he may gently bend the stems and move them away from the centre. This technique, known as low-stress training (LST), helps keep the foliage flat and ensures maximum light exposure.

By using LST at the beginning of the flowering phase of cannabis, yields can be effectively increased by up to 40%.

Weeks 3-4: bud formation

During this period, growth will begin to slow down. However, the plant should be about 50% larger than three weeks earlier.

At this point, the actual buds begin to form, and white pistils will appear to sprout from them.

The plant should still be lush and green during the third and fourth weeks. If you notice a change in colour in the leaves, it could be two things:

  1. Discolouration and rapid leaf loss could indicate a nutrient deficiency. This is an easily treatable problem if caught in time;
  2. If, on the other hand, the leaf tips turn yellow/brown or look burnt, we are dealing with nutation burn. Excess nutrients must be flushed out with pH-balanced water to treat this problem. If left untreated, the plants will no longer be able to produce nutrients.

However, the lower leaves may turn yellow or fall off: this is a normal phenomenon due to the lack of sun in the lower part of the plant.

Read also: Dull trichomes: what it means and how to interpret their appearance

Phase two: mid-flowering

Weeks 4-6: The buds swell

Later, in the flowering stages of marijuana, one can expect the buds to swell and still have a bunch of white pistils sprouting in all directions.

At this stage, the grower should keep the heavy buds upright.

If, however, the plants should grow too close to the lights, the last resort is super cropping: this means forcing the stems of the plants to form a 90-degree angle. We have deliberately called this a ‘last resort’ because this technique risks over-stressing the plant.

More experienced growers are starting to consider strategic defoliation for very leafy plants. It is an excellent tactic to expose the buds to light, but keeping enough leaves to carry the plant to harvest is essential.

Weeks 6-8: Maturation of the buds

Flowering cannabis has entered the next phase: the buds will begin to ripen, and the pistils will darken.

You will no longer notice any vegetative growth, as the plant will devote all its energy to growing potent buds in its final stages.

Here, the experienced grower must be much more careful.


Simple: the plant is becoming much more demanding of nutrients and much more sensitive to problems caused by them. Nitrogen, for example, is not used as much by the plant, and if it accumulates in the leaves, it could lead to self-pollination, damaging the crop.

In addition, you might notice a phenomenon called ‘foxtailing’: a phase in which buds form on the bottom or sides of existing buds. However, foxtailing is not always synonymous with bad news, as it can also be a genetic issue.

Marijuana in bloom

Late flowering

Well, this is the last phase of cannabis flowering.

Week 8+: Flushing and harvesting

Look out for a few signs as you approach harvest time. The variety you are growing will determine the specific week you will be able to harvest.

With a few exceptions, the pistils usually turn orange at this stage, which means that the plant is no longer creating new buds. In addition, at this stage of the cannabis flowering cycle, trichomes change from clear to amber as THC levels increase.

An experienced grower knows that during this phase of cannabis flowering, the plant is susceptible.

Once harvest time arrives, the plants must be washed by replacing nutrients with pH-balanced water. Depending on the length of the cannabis flowering cycle, you will have to rinse for one to two weeks before the expected harvest.

Read also: How to obtain a permit to cultivate hemp for medical use?


In this article, we have tried to give an overview of the flowering phase of cannabis for information purposes only.

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