Fewer hours of lighting are required if the dark period is interrupted in the middle of the night,. The light break in the middle of the night restores pfr phytochrome level. Since neither of the two dark periods before or after light break is very long, the pfr level does not diminish sufficiently to permit flowering. 12-1 plants stay in vegetative state, and grow bigger and better with tight nodes.
8 hour finish
Since the dawn of time, farmers have understood the role of light in plant growth; it wasn’t until the beginning of the twentieth century that we began to understand the importance of darkness. In 1913, the French graduate student Julien Tournois discovered that hops and hemp grown under glass would flower precociously in winter. He also observed that the plants would flower most rapidly when allowed only eight hours of daylight.
Tournois’s research ended when he died on the front during World War I, but a few years later two American scientists, Wrightman Garner and Harry Allard, unwittingly expanded upon Tournois’ findings.
Wrightman and Allard discovered that certain plants bud more readily when they sense a change in seasons, or rather: Certain plants will begin to bud when they sense a change in the ratio of daylight hours to nighttime hours.
Garner and Allard immediately saw the implications for agriculture. They began experimenting on a range of plant species and discovered that day length influences many aspects of plant activity, including dormancy, flowering, and potential yield.
In 1920 they noted: “under the influence of a suitable length of day, precocious flowering and fruiting may be induced.”
Garner and Allard invented a word to describe a plant’s sensitivity to day length: Photoperiodism. Photoperiodism is a biological response to a shift in the proportions of light and dark in a 24-hour cycle.
Photoperiodic plants measure hours of darkness in order to keep track of the seasons and thus flower at an appropriate time of year. The two scientists began classifying plants as long-day plants (LDP), day-neutral plants (DNP), and short-day plants (SDP). Day-neutral plants can flower at any time of year, depending on other conditions.
Long-day plants flower naturally in high summer, when the nights are shortest.
Short-day plants flower naturally when the nights are long: either in early spring or in late summer and early autumn.
Short-day species include chrysanthemums, poinsettias, cosmos, globe amaranth, rice, hyacinth bean, and some varieties of marigold, orchid, and strawberry; as well as and a number of other high-value specialty crops.
Short-day is actually something of a misnomer: short-day plants sense darkness, not light.
When sensors in your plant’s leaves indicate that each 24-hour cycle includes 12 or more hours of sustained, uninterrupted darkness, your plant’s apical meristems (growing tips) will shift priorities: instead of producing more leaves and stems, the plant will begin to produce floral structure.
In Photoperiodism in Plants, Thomas and Vince-Prue expand upon the concept: ”Perhaps the most useful proposal is that of Hillman (1969), who defined photoperiodism as a response to the timing of light and darkness. Implicit in this definition is that total light energy, above a threshold level, is relatively unimportant, as is the relative lengths of the light and dark period. What is important is the timing of the light and dark periods, or, to think of it another way, the times at which the transition between light and dark take place.”
Biologist P.J. Lumsden also emphasized the importance of precise timing, noting: “…photoperiodic responses require a time-measuring mechanism, to which is closely coupled a photoperception system. Further, the time-keeping mechanism must operate very precisely and it must be insensitive to unpredictable variations in the environment.”
In other words: absolute darkness is not necessary to trigger a photoperiodic response in SDP, but consistency of dark-to-light ratios is essential.
During a 1938 experiment on the effects of light on xanthium, Karl Hamner and James Bonner discovered that the benefits of a long night could be reduced or abolished if the darkness was interrupted for even a few minutes.
The converse was not true: the flowering process was not reversed when the daylight hours were interrupted with darkness. Growers of SDP crops have been using light deprivation research to their advantage for decades. For example, poinsettia farmers use automated greenhouses to ensure that plants bloom for the Christmas season.
More recently, light deprivation technology has caught on in other specialty gardening industries. Light deprivation is an ideal method for farmers who want to bring a crop to market before the market floods during the harvest season. The method also allows farmers to avoid potential rain damage by harvesting when weather conditions are ideal. Perhaps more importantly, light deprivation offers the opportunity to plant and harvest twice during one growing season and thereby double annual yield.
To utilize light dep, farmers plant crops in hoop houses or greenhouses, which are covered with opaque material for a period of time each morning or evening. The goal is to block sunlight and increase the number of hours the crop spends in darkness: more than 12 hours of darkness will stimulate flower growth in most SDP plants.
The challenge is to keep the schedule consistent and to ensure that the darkness is not interrupted, either by unseen rips in the covering, shifts in the covering caused by wind, or human error.
As Hamner and Bonner demonstrated, interruptions or inconsistencies in the light deprivation cycle can confuse the plant and slow flower growth.
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Why does 8 on 16 off work so well?
Cannabis can only uptake 8 hours of light energy for photosynthesis, its tanks are full.
When you give it more light energy, the plant goes into photosynthesis protection, which use up energy and shuts down CO2 intake.
So now you are using the energy received to its utmost potential, no energy wasted, no CO2 shutdown, the plant now has 16 hours to grow fatter buds and produce more resin than ever before. 8 on 16 off in flower is the game changer.
All they ever taught you was to spend thousands to make hundreds. 12-1 8-16 is direct aid to all growers. F%#k the status quo.
What are short day / long day plants?
Asters provide color late in the fall, when many flowers are fading into memory.
Ever wonder why you have trouble getting your Christmas cactus or poinsettia to bloom again? Or have trouble with bolting spinach and lettuce in your summer garden?
To understand plant flowering, you need to get a handle on “photoperiodism,” or amount of light and darkness a plant is exposed to. The amount of uninterrupted darkness is what determines the formation of flowers on most types of plants, explained Ann Marie VanDerZanden, horticulturist with the Oregon State University Extension Service.
Botanists used to think that the length of daylight a plant was exposed to determined whether a plant would form flowers. But experiments proved otherwise. It is the length of darkness that a plant experiences that plays the most crucial role.
A plant that requires a long period of darkness, is termed a “short day” (long night) plant. Short-day plants form flowers only when day length is less than about 12 hours. Many spring and fall flowering plants are short day plants, including chrysanthemums, poinsettias and Christmas cactus. If these are exposed to more than 12 hours of light per day, bloom formation does not occur.
Other plants require only a short night to flower. These are termed “long day” plants. These bloom only when they receive more than 12 hours of light. Many of our summer blooming flowers and garden vegetables are long day plants, such as asters, coneflowers, California poppies, lettuce, spinach and potatoes. These all bloom when the days are long, during our temperate summers.
And some plants form flowers regardless of day length. Botanists call these “day neutral” plants. Tomatoes, corn, cucumbers and some strawberries are day-neutral. Some plants, such as petunias defy categorization, said VanDerZanden.
“They flower regardless of day length, but flower earlier and more profusely with long days,” she said.
Horticulturists and home gardeners manipulate the day and night length (indoors with lights) to get plants to bloom at times other than they would naturally.
For example, chrysanthemums, short day plants, naturally set flower and bloom with the long nights of spring or fall. But by making the days shorter by covering the chrysanthemums for at least 12 hours a day for several weeks over the late spring and early summer, you can simulate the light and darkness pattern of spring or fall, thereby stimulating summer blooming.
Or you can bring a long-day plant into bud formation and eventual bloom early before our day lengths surpass 12 hours. Put the plant under grow lights for a few hours a day beyond natural daylength for a few weeks. Adding supplemental day length to stimulate early blooming is a common practice in the nursery and fresh flower industry, especially this time of year, for Valentine’s Day and Easter flowers.
Author: Carol Savonen
Too much light
It really isn’t about a medium, or systems
It’s all about the light hours. Exposing another scam, we were lied to by the media. And the grow industry at large.
It seems like it’s about money. if you were wealthy and could afford college, then you could learn the truth, but for us hard working types (poor), you get screwed.
Like with so much these days, take it from someone who did it the wrong way for 30 years.