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12 12 from seed marijuana

When we germinate a Cannabis plant and plant it correctly, even though we begin to give it only twelve hours of light and twelve of absolute darkness, the plant will not flower. This happens because the plant needs to have certain sexual maturity before it will start to bloom (maturity is obtained between 3 and 6 weeks after it is germinated).

These cycles are designed to imitate nature in a certain way, in spring when the plants grow in all their splendor, they receive more hours of light than of darkness. When summer passes and the days begin to shorten, cannabis plants grown outdoors flourish. This is why they use specific light cycles for the growth and flowering of plants grown indoors.

Cannabis Light Cycles

As the plants do not grow as much as if we had given them a previous growth cycle of growth at 18/6 or 24/0, we will obtain plants that are somewhat smaller in size, so they can take better advantage of the lighting of our focus. Interestingly, they do not develop many branches with this technique, which will allow us to include more specimens in the same grow space.

The first thing we need to know is that plants that are grown to 12/12 from seed finish flowering with a lower height than those that have been cultivated with a growth phase and then another flowering phase. This is something very positive when used to cultivate sativa varieties, due to its height.

We can assure that the flavor and quality do not vary at all, perhaps the production is a little lower, but nothing that is not solved by adding one or two more plants per crop.

Done with expert practice and a willing strain of cannabis seeds, it is not unknown to produce 1 gram of ganja per watt of lighting. That’s an impressive 250g in 7-9 weeks for a 250W light in a small cupboard!

Keep a keen eye out for moulds and mildews as the grow space will be getting less light with more moulding opportunity in warm dark corners and creases.

There are some haters of this method, but many love it. Those who hate on it often have not actually tried it. It is all about giving it a go and seeing what works for you. Even if you decide against it after trying it, it all helps expand your knowledge as a grower.


There is a lesser demand for resources across the boards.
You will experience only half the water consumption with less moisture loss due to evaporation, and a third less nutrients are used. CO₂ and electricity use including most peripherals are reduced by a staggering 650 grow hours annually.
Taking hours to accomplish, tipping, fimming, branch control, and mainlining are now unnecessary freeing up your most precious resource, time.


Plants with less side branching and canopy spread need less space between them, increasing efficiency. As an example: 1x 15-litre pot produces one plant with a large volume and difficult maintenance issues in a cramped space. 4x 3.5-litre pots in the same sized space can produce just as much dried material with the benefit of being easier to rotate, so the whole plant gets 360-degree light. The entire crop is less hassle during maintenance as each plant is 100% accessible and physically easier to move about. There is no need for a separate sprouting and veg space or time wasted on 18-6 vegetation. The seeds can be sprouted under the 12-12 growing lights providing continual flowering plants.

Always be sure to re-sterilize your grow space after each crop.

Other than the difference in the lighting regimen, growing cannabis using this method is the same as the more traditional way. You still need to learn about the other important factors in growing a healthy garden, such as; proper nutrient levels; maintaining the correct PH level; controlling temperature, humidity, and odor; and providing ventilation. Because we are starting from seed, most of us use soil as our medium, although other mediums may be used. Other than that, all other personal choices to control the environment is the same as growing any other way.

Some critics claim that the amount of the main cannabinoid, THC, produced by plants grown this way is less than plants that are allowed to mature with a vegetation phase. This opinion is based on a study done many years ago, well before modern gardening techniques took hold, and almost certainly did not test any plants that were grown using this lighting regimen. New tests must be done, that’s all there is to it. More importantly, the empirical evidence from those who have grown this way, and the experience of their friends who have smoked these plants, is that this cannabis is just as potent as any they have ever smoked (strain variety taken into account, of course). If there is any difference in THC percentages, it is minute, and not noticeable to the cannabis consumer.

This method does have its critics. Most of these critics have never tried to grow this way, they are just passing along commonly held mis-information without having actual experience. The main criticism is that the yields gotten from this method are miniscule and not worth the time involved. We challenge that, with the experience of a grower called “Atmosphere” who gets 1 gram of dried bud for each watt of electricity used (that would be a harvest of 8 ounces from a 250 watt HPS light!). “Atmosphere” had a thread back on Overgrow, which is where many of us first encountered this method, and he is held in high regard among folks who grow this way. He visits this thread and provides solid information based on years of experience.

“12/12 From Seed” eliminates the vegetation phase. As soon as the seed sprouts through the surface it is given a light regimen of 12 hours on/12 hours off. Plants grown this way do not grow as tall as they would if given a vegetation phase. The shape of the plants is also different, losing much of their natural ‘bush’ quality. Our plants tend to be shaped like a “pole,” with the main bud formation happening along the main stem of the plant. This allows the grower to fit more plants per square foot/meter. It also makes possible gardens in spaces that growing larger, bush-like plants would be impossible. The shorter height of these plants also works in concert with the limited penetration distance that exists with any/all forms of indoor lighting.

This thread is devoted to an excellent method of growing our favorite plant. “12/12 From Seed” is a proven way to grow pot, and produces yields up to 1 gram of dried bud per 1 watt of electricity consumed (eg: a 400 watt HPS light is able to produce a harvest of 400 grams). It is a very good choice for growers who have a limited amount of space to set up their gardens. The cannabis grown this way is potent, sticky, and yes stinky. Most pot plants suffer no ill effects from being grown under this light regimen.

Typically, in traditional method, the cannabis cultivator will start their plants with a lighting regimen that provides anywhere from 18 to 24 hours of light a day, called the ‘vegetation’ phase, to make the plant grow as large as possible, increasing the amount of ‘budding sites’ on the plant. Once the plant has grown large, it is forced into flowering by switching the lighting regimen to 12 hours on/12 hours off. This results in plants that produce copious yields, but take up considerable space.

So pull up a chair, and watch what we do. Keep an open mind, and observe our results. Try growing some of your own crops with this method and then make up your mind as to whether there is some mighty fine ganja to be grown this way.