In nature, marijuana plants start to flower in the late summertime to early autumn. When the days start to be shorter and the nights become longer, flowering signals are triggered by photoperiodism, which begins the flowering process and tells the plants that autumn is near.
The female marijuana plant redirects its energy from vegetative development to flowering in order to draw in plant pollen and generate seeds. By manipulating the hours of the night, indoor and outdoor growers can postpone flowering marijuana indefinitely or begin flowering whenever they want.
The conventional method to sustain vegetative development is to keep the light on the plants between 18 and 24 hours each day. The vital aspect is not the hours of light, however the hours of darkness.
With six hours of darkness or less, the plants will continue to grow in its vegetative development as if they were experiencing an extensive summer season.
When it is deemed time for the flowering process to start, the light pattern is changed to 12 hours on and 12 hours off. Increasing hours of continuous night signal the plants to respond as if the Autumnal equinox is approaching and begin to flower marijuana.
By using these light patterns, you can regulate when your marijuana plants flower.
The Science in Layman’s Terms
Cannabis plants are described as long evening or brief day plants because they need a long period of darkness to cause the plant’s hormones to change from vegetative growth to flowering.
These light receptors are color pigments in the fallen leaves called Phytochrome Red (PR) and Phytochrome Far Red (PFR). These pigments acquire their labels from the types of light they take in.
PR absorbs red light in between 660 and 760 nm and PFR takes in red light between 760 and 800 nm. These two pigments chemically react to the light and trigger the plant to flower or not.
In cannabis plants, the typical presence of PFR turns off the flowering signal. The degree of PFR is what you can manipulate by adjusting the photoperiod and PFR is quickly created when plants are left open to light which contains far-red wavelengths.
When there is light, the PFR and PR keep a balance. When the sunlight decreases, or the lighting schedule changes, the darkness slowly switches over from PFR to PR. As a result of this, PR levels gradually enhance and the PFR gradually lessen throughout the dark duration.
When the light returns, or if a small amount of much red light interrupts the dark period, the PR immediately changes back to PFR. If the plants lack light for long enough, the PFR will reduce beyond the tipping point.
This reduced level of PFR indicates to the plants that autumn is approaching, and the marijuana begins flowering. Basically, the existence of PFR, due to long hours of light and short hours of darkness, keeps the plants in the vegetative phase.
If the plant experiences sufficient hours of darkness, many of the PFR revert to PR; and the reduced degree of PFR indicates the plant hormones to begin flowering.
The Best Ways to Start Flowering Marijuana
Due to photoperiodism, you can easily cause marijuana plants to flower simply by changing the light patterns – lowering the light from 18 hours a day to just 12 hours each day.
Once again, exactly what is actually important to the plants is changing from six hours of the night, or much less, to 12 hours of darkness.
Within two weeks of switching over the light cycles to 12-on and 12-off, you ought to see little buds beginning to form. This means that any sort of light reaching your plants during the dark period may screw up the marijuana’s flowering process.
Because of this, one should never ever – not even for a moment – enter the grow area when the lights are turned off in the 12/12 cycle. Prior to you making the change to a 12/12 light cycle, you should make certain your grow space has no light cracks.
Enter the grow room while the lights are out and close the door behind you. Wait approximately 15 minutes for your eyes to readjust entirely, then look around and ensure no light is getting in the room.
While converting to a 12/12 light pattern will cause flowering, there is a trick to jump-start the procedure. In between the change from an 18/6 to a 12/12 light cycle, allow your plants sit in uninterrupted darkness for 36 hours.
This will trigger the PFR to go down significantly, providing the plants a strong signal to blossom. Make certain to flush out high nitrogen “grow” fertilizers from your growing medium and change to a high-phosphorus “flower” formula.
Also, including high potassium supplements for the very first 2 weeks can enhance fast bud development.
Light Deprivation For Outdoor
Via manipulation of photoperiodism, growers can cause very early flowering in outdoor cannabis plants. It is far more difficult to make the open air artificially dark than it is to switch off the lights indoors – however not impossible.
Several growers have developed the fine art of light deprivation and used it to flower their outdoor marijuana crop in summer, and even several times annually. This can be attained by building a garden that can be covered after the sunlight decreases, and then removed in the early morning.
If timed correctly, this could lengthen the organic night to a complete 12 hours of darkness. The garden has to be covered for many hours each day without exception, during the whole flowering period; however, the effort can deliver outstanding early yields.
Power Outages & Light Disruption
Despite light timers and entirely automated growing areas, things often fail. If the power goes out, or you have to change lights, keep your light cycles in the front of your mind. When the garden is operating on a 12/12 light cycle, a short power blackout is not a significant issue.
A couple additional hours of darkness will certainly not gum up the works. Though, the plants will not grow without light; however, they will be fine for at least two days. Any longer than two days and they will begin to suffer yet this will certainly not kill them; however, this could induce them to become stressed.
When operating on an 18/6 vegetative light cycle, a power blackout causing long hours of darkness can cause the marijuana to flower. You need to have an alternate source of power or light source for the garden. An electric or gas camp lantern will be enough to prevent the PFR from going down.
If you have to alter the lighting schedule and disrupt your normal dark period, just leave the lights on until you can resume with dark duration. A few hours of additional light will not harm anything.
Don’t forget, you do not need enough light to keep them growing – just enough to make it not dark.
- To keep vegetative growth, utilize 18-24 hours of light; six hours of night or less.
- To induce flowering, alternate 12 hours of light with 12 hours of the night.
- When switching light patterns from vegetative to flowering, first provide plants 36 hours of darkness.
- To harvest outdoor plants early, cut the time light reaches the plants to 12 hours every day.
- During 12/12 flowering marijuana, additional dark hours are acceptable if required.
- Throughout 18/6 vegetative growth, added hours of light will not create problems.
Effective marijuana growers know how to manipulate the lighting of their garden and are comfortable with light control and photoperiods
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