Growing cannabis: the flowering phase

If you managed your way through the vegetative stage successfully, it’s now time to switch your lights to 12 hours and enter the blooming phase. In this article, we’ll give you some general guidance and tips for a successful flowering.

The flowering phase is when the plant experiences shorter periods of light during the day. Outside, cannabis plants perceive that Autumn (and eventually… Winter) is coming when days become shorter. Female plants will produce flowers, while males will produce pollen. Assuming you intend to produce buds, you will keep female plants only and help them produce large and dense buds until harvest.

Blossoming

Indoor or in greenhouse, you will practice light deprivation, either by switching your light timer to 12 hours of light per day (and therefore 12 hours of darkness), or by hiding your plants from the sunlight (in greenhouse). After a couple of weeks, you will see white hairs appearing on various parts of your female plants. It’s important to make sure that no male plant is around, or they’ll spread their pollen onto the buds and cause females to produce seeds instead of buds.

Within a few weeks, those tiny hairs will become buds. As the buds mature, the smell becomes stronger. This is caused by terpenes, giving buds their smell and taste.

Feeding your plants

During the blooming phase, you need to use a different kind of nutrients. Your plants will need more phosphorus and potassium, and less nitrogen. Remember that they will keep growing in size for at least two weeks after entering the blooming phase. Beyond 3 weeks, they will mainly focus on bud development. It’s best to adjust your nutrient mix gradually each week and observe how your plants react. Start low and progressively increase the dosage until the third week of flowering in order to avoid over-fertilizing.

Note that, some growers do not only feed their plants through the roots but also through the leaves as a way to transport nutrients quicker to the buds.

The blooming period requires a lot of attention since the needs of plants evolve as buds mature. “Listening” to your plants and adjusting the nutrients concentration is key to maximize your harvest. Remember, underfeeding is always preferable to overfeeding, as it’s usually easier to correct.

Airflow

Plants will consume a lot of CO2 during daylight hours of the flowering stage. The more CO2 they find in the air, the faster they’ll develop dense and large buds. CO2 will also increase their tolerance to high temperatures.

An ideal indoor setup is one featuring both air intake and extraction systems. Your extraction should be as high as possible in order to remove the hot air and maintain a favorable temperature.

Airflow will help maintaining an ideal temperature and humidity, in addition of CO2 concentration. The breeze generated by the intake and extraction can be complemented by one or few fans. This will reinforce your plants’ stems and branches. Stronger branches can bear bigger buds…

Third week of flowering and beyond…

From the third week, your plants will dedicate most of their energy to producing buds (generally, though some strains may be more premature or late). The following weeks are very important.

Beyond that period, you will not be able to spray your plants with any pesticides. Buds will dramatically increase in size and sometimes merge into one bigger bud. The trichomes will start appearing and the smell will become yummier every day. You will need to pay increasing attention to humidity as your plants will produce moist. Too much humidity risk causing mould to appear, which will ruin part of your harvest. It is critical to adjust your airflow in order to maintain the right level of humidity at this stage.

Almost time to harvest

During the last two weeks, your buds won’t expand much in size. Instead, they’ll produce trichomes, cannabinoids and terpenes. You may decide to stop feeding your plants if growing in soil, as there should plenty of nutrients left in it until harvest. You may also decide to remove the fan leaves in order to let more light reach the lower buds.

A common rule of thumb used by growers is to harvest when 75-80% of the white hairs have turned brown.

Do you have any special trick to share with us?

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