The relationship between light and dark (day and night) is called the photoperiod.
Flowering begins when the days become shorter, vegetative is when the days are longer.
Vegetative plant hormones are made by the plant 24 hours day and night.
The growth and flowering of plants is influenced by phytochrome hormones. These plant growth hormones are produced by the plant day and night, but the flowering phyto hormones are broken down by light during the day.
The flowering phytochrome hormones prevails as soon as the plant is in the dark and causes the plant to bloom. In 1 hour dark, the plant make much more phyto flower hormones than vegetative phyto plant hormones.
The slightest amount of light during this dark period can seriously disrupt or even stop the flowering phyto hormone production.
That is why it is important never to enter a dark cultivation room, even with a flashlight.
A plant need day time to get the sun light to do the photosynthesis for generating energy.
~ 6H2O + 6CO2 -- Light à C6H12O6 + 6O2 ~
Water + Carbon - Light à energy.
The more light, the more energy the plant can make if there is enough water and CO2. A plant therefore needs both light and dark.
The best brake even point to get the maximum of flowers and fruits is 12 hours light and 12 hours dark.
How to get bigger buds?
If you leave the light on for 18 hours or more, the flower phyto hormones will never gain the upper hand and the plant will always remain in the vegetative phase and therefore grow.
This is the condition for how the cutting farms keep their motherplants.
The motherplant can also be kept in 24 hours of light, but this requires considerably more electricity for the grow lights and it takes longer for a plant cutting to flower after planting in a 12 hour light cultivation room.
A trick some growers use is to turn on the lights longer during the last 2 weeks of the flowering period from 12 hours to 14 hours light per day.
Two weeks before harvest, the plant has sufficient flowering phyto hormones to continue to bloom, but it does receive 2 hours more light per day, and therefore more lumens, so the leaves absorb more light and create more energy and sugars.
Also the plant has 2 hours a day less darkness to consume energy.
This will result in bigger flower buds.
There are also products on the market that contains a blend of natural phytochrome hormones to stimulate the growth and flowering of a plant.
Best is to give these products in day time when there is a stop in the plant to create flowering phyto hormones.
How more you can play with the light?
It may happen that there has been a malfunction in the lighting system and that the lights above the flower buds have not been switched off for a while. The result is stem formation in the flower clusters.
After discovering the malfunction, the solution is to immediately turn off all lights for a period of 24 or 48 hours so that the plant boosts the production of flower phyto hormones to limit the damage.
Growers who want to get their motherplants to bloom should always start by leaving the plants in the dark for 48 hours. In this way, the grower prevents the plants from growing beyond the lamps.
There are also growers who turn off the light for 24 hours sometime in week 3 of the cultivation cycle to keep the plant shorter and bloom earlier.
Metrop GreenXtrem is a blend of natural plant growth hormones.