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fase di fioritura della pianta di Cannabis

Flowering Stage of Cannabis Plant

The flowering stage of Cannabis plant

Welcome everyone to this new article from the Cannabis Cultivation Manual dedicated to the important flowering stage of Cannabis plant! In the previous chapters we talked about the germination stage and the vegetative stage as a fundamental phases of Cannabis plant development. In this chapter we will analyze together the flowering times for indoor VS outdoor crops, but not only. Proper nourishment and compliance with the growth parameters will be the essential basis for going to deepen, in the next chapter, how the flowering of Cannabis takes place week after week!

What’s Cannabis flowering stage?

How many times have we lit a joint of killer weed and thought “how did they make it so good?”. We can answer that, genetics characteristics apart, much of the game is played in the flowering stage of Cannabis plant. In fact, getting to this point with no visible nutritional deficiencies will not ensure your stash of precious personal weed!

The Cannabis flowering stage is the time of development where the plant will begin to create the first buds of Marijuana.

It is recognized by the sudden growth of the plants, followed by the first pre-flowers. This will be, as we will see, the right time to separate the females from the males if regular seeds have been chosen.

This stage can last anywhere from 6 weeks for indica genetics to over 20 weeks for pure sativa. In today’s market, however, it is difficult to find native seeds without encountering hybrids that, on average, have a flowering that lasts from 7-8 to 12-14 weeks.

Indicas, mainly found in areas of the Middle East (such as India, Pakistan, Afghanistan, Nepal, Mongolia, etc.). They are low and compact plants with a very short flowering. Genetics such as Skunk 1#, Afghani and Northern Lights represent cornerstones of today’s Cannabis Indica market.

From otherside, Sativa is a relative native to the areas of the tropics, where the summer is very long. It can still be seen growing spontaneously today (in areas such as Jamaica, Colombia, Mexico and Thailand), and is recognized as tall plants with extremely long flowering. Strains like Jamaican Pearl, Hawaiian Snow and Amnesia Haze are what we recommend for lovers of true Sativa qualities!

Start of Cannabis flowering stage

If you grow them outdoors, you just have to wait for the reduction of the hours of sunshine to make the plants pass from the vegetative phase to the flowering phase. Normally this happens towards the end of July and the beginning of August, a few weeks after the day with the most daylight hours of the year (21 June). If, on the other hand, you are growing indoors, the “summer solstice” will have to happen by simply changing the light cycle of your lamps. It will therefore be sufficient to pass from the recommended cycle 18/6 (or 20/4) to 12/12.

An 11/13 cycle can also be held to increase flowering speed, at the expense of production.

As mentioned in the last paragraphs, the beginning of the flowering phase of Cannabis occurs with the birth of the first flowers. In growers’ parlance, they are called pre-flowers and are the exact indication of which sex the plant will soon develop. An initial stretching phase will then accompany the formation of the first calyxes. You can easily reduce this by continuing to grow with white light, waiting a couple of more weeks to switch to HPS lamps.


The environmental parameters to be respected in the initial flowering phase of Cannabis are practically identical with the vegetative phase.

In fact, once the light cycle has moved to 12/12, the plants will not change their needs or habits right away.

The ambient temperature must therefore be 18-21 ° C at night and 28-31 ° C during the day. Too high temperatures could lead to the onset of plagues and insect infestations such as the dreaded red spider. On the other hand, too low temperatures could lead to molds like Botyrtis, which would inevitably lead to throwing away the infected parts of your precious crop!

The humidity must continue to be medium, in a range that can go from 40% to 65%. Humidity also plays the same factor as temperature, you must avoid reaching peaks that are too high or too low.

Correct Feeding

In this initial Cannabis flowering stage it will still be possible to continue to give nitrogen in the proportions required in the vegetative phase.

Do not change the diet of the plants immediately after changing the light cycle.

In fact, in the transition period between vegetative and flowering, the plant maintains the same nutritional needs. An NPK ratio of 6-3-2 will be optimal, not forgetting important trace elements such as calcium, sulfur and iron.

Humic and fulvic acids can speed up the decomposition process of soil nutrients, making them immediately available to the roots. This is why we recommend growing Cannabis with Mycorrhizae, a special fungus which, living in symbiosis with the roots of Cannabis plants, improves and promotes absorption processes, protecting the roots from parasitic attacks.

Flowering Stage in a Cannabis Plant

Final stage of flowering in Cannabis plant

We wanted to divide the flowering in two. The first phase is where the plant begins the production of new branches and first flowers. The final flowering phase is where the flowers need to be inflated with sparkling resin, cleaned of mineral residues and preserved from high temperatures as they degrade terpenes and active ingredients.

We all know how wonderful it is to see plants starting to put their precious first flowers. However, it will be important to know how to wait for the flowers to be ready before being able to detach them and try them on. If removed too early, Marijuana flowers have very low active ingredients and a taste similar to field grass. We do not recommend testing before 25% red pistils appear.

Therefore, observe daily the oxidation state of the pistils will help you understand when your Marijuana will be ready. This is the only way to tell with the naked eye when the end of cannabis flowering is near. Otherwise you will have to purchase a pocket microscope (60x will be fine) to see the status of the trichomes.

Microscope is the most recommended way to decide when to cut your cannabis plants.

We will talk about the two ways to understand when Cannabis is ready in the next article, keep following us!

Flowering Stage in a Cannabis Plant

Parameters of flowering stage

At this point, the ambient temperature will have to be slightly lower, same thing for the humidity. It will therefore be good to have from 18 ° to 25 ° C, with a humidity of 40-50%.

If you are growing particularly productive cannabis genetics indoors, the risk of developing molds in the flowers is very high if you do not run an adequate air recirculation system in the grow space. Outdoors you will have to worry about rain and bad weather, often present in the northernmost areas at the end of the summer season.

Correct Feeding of flowering phase

We at Annibale wanted to divide the flowering into two parts even in our organic fertilizers. We have analyzed how, from the beginning to the final flowering phase, Cannabis plants required nutrients in different ratios. So, it will not be enough to use the same fertilizer throughout the entire flowering to obtain the maximum result!

In fact, when the plants stop their growth to devote themselves exclusively to the formation of flowers, around the 4-5th week (depending on the cultivated strain), the need for nitrogen (N) will be decidedly less, while a greater supply of phosphorus (P) and potassium (K) will be essential in the development of large and heavy Marijuana flowers.

Flowering Stage in a Cannabis Plant

5 Tips and advice for Marijuana flowering stage

We know how essential it is to respect the various needs of cannabis plants in this delicate final phase. For instance:

  • Nitrogen remains one of the most requested nutrients in the first flowering stage. However, too much nitrogen in the final stage will result in a flower with an unpleasant smell and taste. In this case, the joints will have a hard time burning.
  • As plants begin the flowering phase, initial stretching may be a problem for even the most experienced grower. Knowing when to change the cycle of lights and lamps, or how to treat the plants to induce them to develop more low buds will not only save the situation, but also bring out the best from the entire growing cycle!
  • Shining big buds may tempt even the most patient grower to remove beloved buds too soon. Knowing how to wait for the best time to harvest will therefore be essential to obtaining the best results. Be patient!
  • Touching the flowers too much can lead to premature degradation of the active ingredients of Cannabis. The result is in a flower that is poorer in THC, CBD, and aromas and essential oils.
  • A light with strong UV-B rays aids in the development of trichomes. CFL growlamp contain a wide range of UV-B rays. You can therefore wisely add it to increase the formation of precious Cannabis trichomes!

And that’s all for today, keep following us to find out more about the “first stage of Cannabis Flowering“!


Davide, CEO Founder & Geneticist