After a couple weeks of growing, you will have to start the flowering period.
Just like other plants, the cannabis plant wants to develop flowers/fruits (= seeds). The plant will start to use its energy to produce tops/buds. If the plants gets pollinated, the seeds will develop inside these tops. But the whole idea is to stop the plant from developing seeds. Instead, the plant should continue to put its energy into producing tops without seeds and “false seed pods” that are bursting with THC. You can stop the plant from developing seeds by making sure it does not come into contact with male plants.
Depending on the strain you use, the time to start flowering varies. Usually, this information is provide by the breeder or the shop where you buy your seeds. You can start the flowering period by changing the hours of light the plants are getting every day. In nature, the flowering starts when the days become shorter. If you are growing indoors, you will have to imitate the natural situation yourself. You can also simulate it in greenhouses. You just need a very large carpet.
The total flowering period also depends on the variety of cannabis you are using. It is important to stop flowering at the perfect moment, when THC-production is at its highest.
How do I start the flowering period?
After the dark period, change the light cycle to 12 hours a day. Do not interrupt this interval ! Make sure that each day your plant gets 12 hours of light and 12 hours of darkness. You can increase light strength to 40.000 LUX
Nutrients during flowering period
As soon as the preflowers appear (after 1-2 weeks), you can find out which plants are male and which are female. Female plants have 2 very small white hairs sticking out of a small bubbly area at every node (place where the leaf is attached to the stem).
How do I end the flowering period?
If you have enough time, expose the plant to 12 hours of light and 12 hours of darkness all through the flowering period. This method will produce bigger yields, but takes more time. In doing so, the flowering period will increase up to 3 weeks.
If you need your harvest faster, use the 12 hours light method for 1-2 weeks. Separate the males and continue the 12 hours light method for the females for another 3-6 weeks. If you think your buds are big enough and ready to harvest, change the light cycle to 8-10 hours each day. After 2-3 weeks, you can harvest your plants.
Keep the plants in total darkness for 24-48 hours.
Be careful: even the slightest ray of light can interrupt this process. During the period of total darkness the plant will produce an overdose of a certain hormone. When the production of this hormone reaches its peak, the plant will know it’s time to start producing flowers.
During the flowering period, you can give special nutrients to your plant. They should contain the specific substances the plant needs during this period. Feed the plants with additional nutrients every time you give them water. Flowering plants need fertilizer with little nitrogen and a lot of phosphorus.
Keep humidity low (60%) after the flowering period has started. Do not spray water very often. This is to prevent mold and rot.
There are 2 ways to end the flowering period and start harvesting. The fast way, is to harvest as soon as possible. But there's also a longer way, which gives higher yields and more resin production.