By Dennis Blanc,
Last update: February 05, 2019
End of the growing phase / begin of the blooming phase
A marijuana plant has a growing phase and a blooming phase. This has to do with the period of time
the plants are exposed to light per day.
Indoor growing phase
The growth period for indoor growing is easy to control. You can set the time clocks for the desired
period of light. To start the growing phase, the period of light should be set to 18 hours of light and
6 hours of darkness per day. As long as you keep to this light duration, the plant stays in the growth
Indoor blooming phase
After the plant has reached the desired length (usually after 2 weeks of growing), the light duration is
reduced to 12 hours of light and 12 hours of darkness per day. Due to the shorter period of light, the
plant will assume the summer is over and start its blooming phase. There are early and late blooming
varieties, but on average the plant will bloom for 8 weeks until it is ready to be harvested.
The moment you adjust the light exposure is also the moment when you must switch from
growth fertilizer to bloom fertilizer.
Outdoor growing phase
In outdoor growing, the growing phase starts with the germination of the marijuana seeds in early
springtime. The best time to place the young plants outside is when you are sure there will be no more
frost during night-time. This should coincide with the moment when the daylight hours per day will
start to increase, so the plant will know springtime is coming. This is comparable with the 18 hours
of (lamp) light per day indoors.
The plant will stay in the growing phase until the end of the summer when daylight hours will start to
decrease again. This is the end time of the growing phase and the begin of the blooming phase.
Now you must switch from growth fertilizer to bloom fertilizer.
Outdoor blooming phase
One or two weeks after the end of the growing phase, the first signs of the blooming phase will start
to appear. It starts with fine white hairs (pistils) growing on your female cannabis plants. These white
pistils will later become the marijuana buds.
In every country the blooming phase starts on a different date. Unfortunately, it is not possible for us
to lists all the different dates when the blooming phase starts in all the countries of the world. In
The Netherlands, for example, the blooming phase starts around the end of August and most plants
will be ready to harvest at begin / mid-October. Most European countries can adhere to these dates.
For other countries, we advise checking first the dates for the blooming phases. Or you can also wait
till you see the first signs of the blooming phase and then switch to the blooming fertilizers.
Seven weeks after the estimated begin of the blooming phase you can add the boost fertilizer for extra
heavy buds full of THC.