12/12 from seed

The 12-12 from seed technique – is it a good idea?

Indoor cannabis growers are always looking for new, speedier ways to grow high-quality weed indoors, in spite of the obvious space limitations. Some cultivators use a particular method known as the ‘12-12 From Seed‘ technique, which skips the traditional vegetative phase altogether.

Let’s look at what this means:

What does 12-12 from seed mean?

Photoperiod cannabis strains which are grown with feminized marijuana seeds reach the flowering phase based on their light cycle. To reproduce these conditions, indoor growers use different light cycles to keep plants in their vegetative stages and then force them to flower.

Therefore, they usually use an 18-6 light cycle to keep their plants in a vegetative phase for around two to four weeks and then switch to a 12 -2 cycle for the flowering stage, so the plants receive equal amounts of light and darkness.

This has been a standard indoor growing method for hundreds of years, and there isn’t anything particularly innovative about that. However, some growers use a cultivation technique known as the “12-12 From Seed” method.

As the name suggests, this is about skipping the initial vegetative phase and immediately forcing the plants into flowering as soon as the germinated seeds begin to protrude from the ground.

Advantages of the 12-12 from seed method

The 12-12 system saves you about five weeks’ worth of time and power. This makes the system a lot better for the environment than a system where there is a lengthy vegetative phase. Moreover, because you grow in this way, the cannabis plants have fewer leaves and relatively more bud. This makes them easier to harvest, and they have a nicely styled appearance. The 12-12 system works best for indoor cultivation, but can also be used outdoors by darkening.

  • Each part of the plant is fully exposed to the light – right down to the ground;
  • Less problem pruning because there are far fewer resinous leaves to process;
  • Plants are easier to handle for maintenance;
  • Cultivation is possible in tiny spaces;
  • Avoids wear and tear due to the displacement of components;
  • You’ll save money on electricity due to the shorter time to harvest.


  • You will need to spend more money on seeds at the beginning.

That’s pretty much it in terms of the negative side of the 12-12 from seed method, although some growers feel that it has a slight impact on the quality of the bud. Just give it a chance and find out if it works for you. Even if you decide it’s not for you after trying, the experience will help you learn more as a grower.

Tips for growing 12-12

  • Watch out for the humidity of the earth as lamps will dry out the soil faster than if a canopy protected it;
  • Start from the very beginning with 12 hours of light and 12 hours of darkness;
  • Avoid stress and provide plenty of high-quality light;
  • Place all plants in one large container with soil (or rock wool, clay granules, etc.).

Useing Sativa dominant cannabis strains – some Sativas will stretch up to 1.2 metres with this method, so selecting the right species early on is critical. Indicas are an obvious choice for maximum space savings. They are generally smaller, and the 12-12 technique will make them very manageable. You will love these little pots filled with bud stems, like a miniature fragrant forest. Buds grown this way are indistinguishable from plants that have gone through a vegetative phase when it comes to flavour and high, and ultimately having buds in your jar faster and more often is a good thing.

Feminised cannabis seeds are ideal with the 12-12 system, but regular cannabis seeds may be a bit cheaper when you start working with the 12-12 system. In that case, sow more plants and keep a close eye on the plants. As soon as you recognise males (after a week or two, the first bloom starts), you should remove them. The results are best when you put the plants in one large container with this system. This will allow them to compete with each other for the light and quickly climb up and still reach a nice size. In this way, you can save a lot of costs on energy and thus relieve the environment while you can quickly harvest as much or even more weed.

The top 3 best strains for 12-12 from seed

Want to grow a strain 12-12 from seed? These species are suitable:

1. Jack Herer

Named after a renowned cannabis activist, Jack Herer has won nine elite awards and is recognised as a caviare of hybrid strains. It has also received one of the highest pinnacles of achievement – the license to be distributed under medical supervision in Dutch pharmacies, thanks to its recognised therapeutic qualities.

The “high” of the tropical Sativa and the colossal resin production of the Indica form a sublime alliance in Jack Herer. The fully mature buds are covered so densely with translucent hair that they resemble icing sugar or appear to sparkle with dewdrops.

Three of the four main Jack phenotypes have a marked Sativa tendency. In contrast, the fourth has an Indica-like growth pattern – fast flowering and relatively compact, dense structure, abundant and rounded “buds” suitable for commercial cultivation. These characteristics make Jack Herer the ideal choice for the 12-12 from seed method.

Jack’s Sativa phenotypes can also give a good yield per yard or per plant when cultivated with care. The trait that all Jack Herer phenotypes have in common is their dazzling double-acting potency – a stratospheric cerebral “high” reinforced by an impressive stone of seismic power. Smokers should be prepared to experience something like an earthquake – which can be a very enjoyable feeling when their head is firmly planted in the clouds.

2. Bruce Banner

Bruce Banner is one of the most iconic and one of the strongest cannabis strains of all time. Bruce Banner is a particularly flavourful cross of the famous Kush aroma and diesel undertones. With 50% Sativa and 50% Indica genetics, it achieves high THC percentages and is very mould resistant.

The Bruce Banner strain is an innovative phenotype bred by crossing a Strawberry Diesel and an OG Kush. Some phenotypes have even been measured with 27% + THC! In other words, if a friend offers you Bruce Banner, take it easy!

The high starts with an intense “punch in the face”, then quickly transitions to a happy, giggly euphoria. After a potential laugh kick, Bruce Banner lets you sink into the couch where you will experience a state of extreme relaxation.

Bruce Banner is undoubtedly a strain for the true cannabis connoisseur who wants to add unique high-grade cannabis to their stash.

Bruce Banner also behaves wonderfully in your grow tent not necessarily growing as a dominant Sativa or a dominant Indica. It does not stretch very hard in flowering so works well for the 12-12 from seed method.

Make sure you take the time to cure this strain properly! This is very important to maintain this excellent terpene profile.

More information | Bruce banner strain seeds

3. Northern Lights

Northern Lights is one of the last few pure Indicas. This makes her grow robust and compact, terms that also apply to her buds. During flowering, this plant gives off relatively little odour, making it very suitable for the discreet cannabis grower!

Forty years ago, Northern Lights set the standard that other Indicas are still judged by today. The Lady remains one of the most trusted names and most demanded varieties in cannabis culture today. She dominated the various harvest festivals for years, winning prize after prize. This led to multiple requests to withdraw her from competitions so that the competition would also have a chance to win a title.

Like most of its relatives, this strain is usually grown indoors under lights. She also does very well outdoors, due to her mainly Indica genetics.

Northern Lights carries on the traditions of her classic ancestors, producing fast, reliable yields with surprisingly little smell during the grow. Still, her buds have a sweet scent and are incredibly potent due to their thick coating of THC-rich trichomes!

What are the advantages of growing 12 – 12 from seed and how to apply this method? Check it out!

How To Grow Cannabis From Seed Under 12-12 Lighting

Force flowering marijuana from seed can provide excellent quality, resinous flowers, all the while saving space, time, and money. For those with space constraints, it is a win-win!


Do you want to go from seed to bud quicker and cheaper? A faster, space saving and economical way to grow is the no veg, seed to flower, 12-12 light cycle method.

Growing with a 12-12 photoperiod is a solution to space and resource problems. This method eliminates the vegetation phase of growth and forces the plant to go straight into flower from a seedling. Yields are lower than that of a regularly grown cannabis plant, but results are obtained much faster, with a few advantages.

The 12-12 lighting technique makes the grow cycle 7-9 weeks in general, rather than the much longer time needed when giving plants a vegetative phase. For the space constrained, and those willing to experiment and give it ago, it can be a dream come true.

WHAT IS 12-12?

12-12 simply refers to the hours of light and darkness a cannabis plant is exposed to – 12 of each. Normally, a cannabis plant is exposed to an 18-6 light cycle. This tells the cannabis plant conditions are good for growth, and it focuses on building up size and foliage. When light cycle is changed to 12-12 (either naturally or through human intervention), it tells the cannabis the seasons are changing, and it is time to flower. By forcing a 12-12 light period from the start, the cannabis plant goes directly into flowering, in a bid to reproduce. You are essentially tricking the plant into thinking the growing season is coming to an end, so it needs to produce flowers ASAP.


Growing 12-12 is as simple as changing the timing on your light cycles, giving your plants equal amounts of day and night right from when they sprout. The plants will look different to a cannabis plant that goes through vegetative growth. Photosensitive hormones in cannabis make the highest point the largest cola. This method all but guarantees only main bud growth on every small plant. Essentially you will be growing a cola with a few short, budded side branches – with the plant basically being a bud in itself. Be sure to stake your plants.

Everything to which you would pay attention in a normal grow remains unchanged and are still just as important. pH and water quality, nutrient mixing, pest control, grow medium conditions, EC and ppm all still play their major roles in the dankness and weight of your finished product.

Growing this way still requires all the knowledge that would be needed to flower plants with any other method, and maintenance routines still remain unchanged. After diluted nutrients, while still young, treat your plants as you would during a normal bud cycle. However, flush more often, every ten days at most, so as to avoid salt build-up in the smaller pots.

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!


  • Lights have full penetration to the floor. Keep an eye on the soil wetness as lights will dry the medium quicker than if protected by a canopy
  • This method is fast. 7-9 weeks on average
  • Less drama trimming as there are far less sugar leaves to deal with
  • Plants are easier to handle for maintenance
  • Can grow in tiny areas
  • Save wear and tear on moving components
  • Save money


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.


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.


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

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.

Some sativas will still stretch to 1.2 metres using this method, so species selection right at the very start is key. Indicas are the obvious choice for maximum space saving. They are generally smaller, and 12-12 will keep them very manageable. You will enjoy small pots full of colas, like a miniature stinky forest. Buds grown this way are indistinguishable from vegetated plants in flavour and effects, and at the end of the day, getting buds in the jar quicker and more often is a good thing right?

How to force cannabis to flower from seed for quick, resinous yields using a 12-12 light cycle.