Get the most out of your cannabis seeds and plants with a thriving flowering stage indoors!

When the germination and vegetative stage are completed, it is time for the flowering stage to begin. This means that your plants will start to flower and develop buds. In this stage the plant grows all its medical benefits and you are now only one step away from harvest.


Watch for the Flowering Stage signs!

How Long is the Flowering Stage?

Similar to the vegetative stage, the flowering stage can vary a lot between different strains. Normally the length of the flowering stage is between 1-3 months. This will also vary a lot between the different strains.

The choice of strain effects the plants size,, although here are 2 tips on what to look for when deciding that it is time to start the flowering stage;

  • When the plant reaches a height of 50-60cm,
  • When the stem and branches has developed  white hair”


Flowering Stage Light Schedule

The flowering stage is activated by changing the lightning hours that the plant is exposed to. (This do not apply on any of the auto-flowering varieties).  In the vegetative stage the plant was exposed to 18-24 hours of light every day.  To activate the flowering stage, change the lightning to 12 hours of lightning exposure followed by 12 hours of darkness.

There are 2 ways to put your plants in the flowering stage, either make the lightning switch immediately or you can give your plants a few days to adjust by gradually changing the hours of darkness each day. Staring from 6 hours then adding 2 hours of darkness a day until you have reach 12 hours. The dark hours of the flowering stage must be complete. Any alteration with the darkness hours can confuse and stress your plants and even ruin your harvest. If any work must to be done during that time use green wavelength bulbs.

We strongly recommend that you keep your plants in the same cycle throughout this change of lightning hours. Meaning that if the 18 hours of light started at 8 o’clock during the vegetative stage, the 12 hours of light should still start at 8 o’clock throughout the whole flowering stage.

The position of the lamp and distance from the plant should have been closely checked throughout the whole process. This procedure needs to be maintained just as carefully in the following steps from germination to the flowering stage. Keep the distance between the plant and lamps to around 40-50 cm. This prevents your leaves to get burned.

Flowering Stage Nutrients

Your cannabis plants need different amounts of nutrients during the flowering stage.

The plant still requires some nutrients when entering the flowering stage.The fertilizer’s may vary from previous stages. Make sure that the plants are getting enough of the nutrients they need, and stop adding the ones they no longer require.

Nutrients Before the Flowering Stage

In the vegetative stage the plants require fertilizers that contains nitrogen, phosphorous, and potassium. When starting the flowering stage you should minimize the use of nitrogen and instead focus on increasing the use of potassium and phosphorous (also called PK). These fertilizers are known as bloom fertilizers.

Lets talk N,P and K!

In this stage the focus is mainly on preparation for the plant to begin producing buds. What many growers forget is that the plant will continue to grow during this time. Therefore some still use the grow fertilizers (N-P-K) the first 2 weeks of the flowering stage. Other growers change to the bloom fertilizers (P-K) at the same time as the lightning hours changes. If you choose to switch to bloom fertilizer immediately the growth of your plant will be slowed down. If we have a small space or grow room for your plants and need every area for your existing plants, this a preferred method.

Be careful not to use too much fertilizers. Always follow the instructions provided by the manufacturer for the specific product you are using. If your cannabis plants are showing signs of suffering, first check all possible sources before increasing the use of fertilizers. Overuse of fertilizers in this stage can damage your harvest and give your yield a bitter taste.

The Importance of Air Quality in the Grow Room

If you expose your plants to lots of CO2 , the growing process will be faster and your plants will be able to endure a higher tolerance for heat exposure.

It is important that you create a good general air flow for the plants in addition to the CO2. In this stage when the cannabis plants have grown large and bushy they might be squeezed tight together in the grow room. It is crucial that the airflow infused with both CO2 and oxygen, is allowed to move through the plants and their leafs. To achieve the ideal air flow in a grow room, we recommend using fans that can circulate the air and imitate natural wind breezes. Fans can also be helpful in lowering the humidity level in the grow room. Never place your fan pointed directly to the plants.

In the vegetative stage the plants require a higher humidity level of 60-70%, when they enter the flowering stage it is recommended to lower the humidity level to about 40-50%. This should be done in different stages by decreasing the percentage every week until you have achieved the recommended humidity level of 40-50%.

The 4 phases of the Flowering Stage

During the Flowering Stage, your cannabis plants go through four sub-phases.

  • 1. The plant is ready to enter the flowering stage when it is approximately 50 cm, or when it has “white hairs” visual on the inner branches of them stem. This is called a pre-flowering stage where the plant is preparing its growth of buds.
  • 2. In the next step of the flowering stage, more “white hair” will develop along the branches. The actual flower of the plant will start to develop along with strong supportive leaves. Small buds will start to show.
  • 3. This step of the flowering stage the cannabis plant will grow thick, larger buds and the production of THC and CBD (cannabinoids) will thrive. This step lasts between 2-5 weeks. Caution; Too much heat exposure in this stage can cause the buds to stretch too long, making them less potent after harvest. 
  • 4. This final phase of the flowering stage will indicate that it is soon time for harvest. The “white hairs” mention above, will get darker and begin to curl. The trichomes will turn white, and the color of the resin on the leaves and buds will turn darker brown or orange. It is time for harvest when about 70-80% of the hair has turned darker and the majority of the resin has changed color. When your plants are showing these features, don’t wait to long to harvest, risking the buds to overripe and get less potent. Around 1-2 weeks before harvest it is recommended to flush out all the nutrients. That can easily be done by watering the plants with PH neutral Water. Clearing your plant of excessive nutrients will improve the taste of your buds. Your plant is now ready for the next step –  Harvest