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flowering cannabis from seed

Flowering cannabis from seed
Is time really of the essence for you? If so, one of the best ways to maximize yields in as little time as possible is to grow an auto-flowering strain. Autos get 18 hours of light a day their whole life, which allows them to get bigger in less time than plants under 12/12. Auto-flowering plants on average are ready to harvest in just 3 months from seed (which is less time than almost any photoperiod plant will be ready to harvest, no matter what light schedule you provide) and generally yield 1-2 ounces per plant.

Is 12-12 From Seed Worth It?

Is 12/12 from seed worth it? Is it a good way to get big yields as quickly as possible? In a word, no… but there is truth to the idea behind initiating the flowering stage as soon as possible! When modified slightly, the same basic technique will give you much bigger yields while adding little to no extra time before harvest.

A “12 /12” light schedule means giving your plant 12 hours light & 12 hours darkness each day (this initiates the cannabis flowering stage)

If you haven’t heard this term before, “12/12 from seed” means giving your cannabis seedling 12 hours of light, and 12 hours of dark each day from the moment of germination. Providing a 12/12 light schedule initiates the flowering stage and causes cannabis plants to start making buds. The idea is to get a new seedling to start flowering as quickly as possible, so it takes less time to harvest.

There’s just one major problem… 12/12 from seed causes stunted growth and small yields. This results in yields that are often less than 1 ounce per plant, even under strong grow lights.

This seedling took 4 months from seed to harvest, and yielded only 1/2 of an ounce. I think it looks kind of cool, but 1/2 ounces is not a good harvest after waiting so long. You can double or triple your total yields per plant by tweaking the light schedule a little during the first few weeks

The problem is that seedlings can’t start flowering until they’re 3-4 weeks old no matter what light schedule you give them, so there’s no point in starting right at 12/12 when they’re under 3 weeks old. When you give the plant 3-4 weeks of 18/6, THEN switch to 12/12, you will get far better results because the plant will get more light in those crucial first few weeks and end up much bigger by the time it’s ready to make the switch.

These plants are 3-4 weeks old and have been under a 18/6 light schedule from seed

A 12/12 light schedule was initiated right after the above picture. Here are those same plants a little over a month later, after they’ve started making buds (plants will double or triple in height after the switch to 12/12, especially young plants). As you can see, they are already far bigger plants than the first example, and bigger plants can support bigger buds.

This is how you achieve plants that look like the one below at harvest (why was this plant defoliated?). Because the plant was allowed to get bigger before it started flowering, it yielded 3-4 times as much as the plant given 12/12 from seed.

By giving plants just a little more time to grow before initiating 12/12, you will be rewarded at harvest time. If you give your plant a solid 4 weeks of 18/6 first, your plant will be ready to harvest around the same time as a plant given 12/12 from seed (

3.5 months, maybe a few days later), but you will get far bigger yields.

What is “Sea of Green” (SoG)?

“Sea of green” is the idea of growing many small plants instead of just a few bigger plants. The advantage is that you are able to get to harvest more quickly because each plant doesn’t have to grow as big to support the same number of bud sites.

For this grow style, growers usually switch to flowering when plants are around 4-6 weeks old; plants switched sooner than 4 weeks may not have enough time to really get the most out of a SoG setup. Adding an extra week or two of veg can make a pretty big difference on yields though, so it’s about finding that balance between getting to harvest as quickly as possible versus harvesting a lot of bud.

For SoG, wait to switch to 12/12 until plants are about this size or a little bigger (note: young plants like this can and will double or triple in height after the switch to 12/12)

Auto-Flowering Strains – When Time is of the Essence!

Is time really of the essence for you? If so, one of the best ways to maximize yields in as little time as possible is to grow an auto-flowering strain. Autos get 18 hours of light a day their whole life, which allows them to get bigger in less time than plants under 12/12. Auto-flowering plants on average are ready to harvest in just 3 months from seed (which is less time than almost any photoperiod plant will be ready to harvest, no matter what light schedule you provide) and generally yield 1-2 ounces per plant.

Auto-flowering strains are ready as soon as 3 months from seed, and yield an average of 1-2 ounces/plant, and possibly even more if you do low stress training (LST).

Flowering cannabis from seed
“12-12 From Seed” is a misnomer if you’re trying to force your cannabis to flower early – 3 weeks from seed is the earliest time a plant can start flowering after the switch to 12-12

12-12 From Seed – Flowering Plants Early

The term “12-12” means you’re giving your cannabis plants 12 hours of darkness, and 12 hours of light every day. “12-12 from seed” mean you’re giving a cannabis plant a 12-12 light schedule from a very young age to force it to flower early (make buds).

Some growers are attracted to the idea of 12-12 from seed, because it means that harvest will come sooner. How long does it take to grow a plant from seed to harvest?

But does the 12-12 from seed technique work to give you a faster harvest, and if so, what are the results?

I have changed cannabis plants over to the flowering stage from seed, but no matter what the light schedule, plants don’t start flowering (making buds) until they are about 3 weeks old. Initiating a 12-12 light schedule at 3 weeks old from seed is as early as I’d recommend for this technique, if you choose to use it.

“12-12 From Seed” is a misnomer if you’re trying to force your cannabis to flower early – 3 weeks from seed is the earliest time a plant can start flowering after the switch to 12-12

Make sure to let your young marijuana plants get a minimum 2-3 weeks in the vegetative stage before changing them over to flowering. Your plants will be healthier and will start flowering at the same time as if you started 12-12 from when they first sprout.

Giving a 12-12 shedule when a cannabis plant is younger than that will not work to make the cannabis start flowering – a cannabis plant will only grow vegetatively for the first few weeks of life, and giving them less light will only cause them to grow more slowly.

Some strains of cannabis will naturally start flowering after about 3 weeks, and you don’t need to do anything with light schedules to cause that to happen. These strains are known as “autoflowering” or “Ruderalis” strains.

Many Growers Who Want To Force Cannabis Plants to Flower at a Young Age May Be Interested in Auto-Flowering Strains – No Need for 12-12 and Often Much Better Yields!

I have grown a few plants from seed to harvest just in a solo cup container. I was able to do this by flowering a plant from a young age – giving the plant 12-12 lighting when it was only 3 weeks old (pictured here).

These solo cup plants were able to survive their entire lives in a small container. I wouldn’t recommend a solo cup because they tip over easily, and plants are prone to nutrient and root problems once the flowering stage begins (the root space is just way too small, even when doing 12-12 from seed or using an auto-flowering stage).

But it’s possible.

The downsides… When your cannabis is kept in a too-small container, you will notice that you have to water your plant much more often than if you kept your plant in a big pot. As time goes on, plants are also more likely to suffer from nutrient problems and root problems because the roots aren’t being give enough room to spread out. When plants become root-bound this way, there’s not much you can do about this besides transplanting your plants into a bigger container.

While I wouldn’t recommend 12-12 from seed, and no longer ever use this technique myself, there are growers who are going to do it anyway.

For those growers who still want to use 12-12 from seed despite the warnings here…

If you are set on keeping potted cannabis plants in small containers for their whole lives, the smallest container you should try is a 1-gallon or 2-gallon container, like the pots pictured here.

Keeping plants in tiny containers may be important when growing in a very space-limited grow space, such as growing in a space bucket for stealth reasons.

There are powerful cannabis growth control techniques that will also allow you to grow high-producing plants, while keeping them short.

But like this extreme girl to the right (less than a foot tall and grown under CFLs), I’ve experimented starting the plants on 12/12 from seed to keep plants REALLY small.

When forcing your cannabis to flower early, plants will stay small and spend almost all their energy on producing flowers/buds on what few stems they have, instead of growing tall or making more colas/nodes.

Some people say that cannabis that is forced to flower too early will not make any buds, but that’s not true. The plant pictured here produced 0.75 ounces of bud after drying. So while 12-12 from seed may not be optimal, it does work.

The problems I’ve had with forcing cannabis to flower early is that since the plant is much smaller, you get smaller yields, but you’re still basically spending about the same amount of time to grow the plant as if you’d grown it bigger.

Compared to 12-12 from seed, growing an auto-flowering strain will generally give you bigger yields for the time, and will be less trouble

With such small plants, you don’t have the time to train your plant, which gives you much greater control over the final shape and size of your plant, improving yields without adding much time.

The other disadvantage to overly small plants is their inability to recover well from problems: you have fewer leaves as a ‘buffer’ so the plant can’t bounce back when something goes wrong such as a pest attack. In a too-small container, as roots get more root-bound, cannabis plants have a harder time using nutrients efficiently, and may start showing nutrient problems.

Growing extremely tiny marijuana plants is fun, but honestly you’ll get the biggest yields by instead investing a little more time in the vegetative stage to train your plant to grow into the exact shape you want. Or just grow an auto-flowering strain.

Auto-Flowering Strains – A better way to force plants to flower early

Plant Training Techniques – Make your plants grow how you want

Learn About Grow Lights – Which is best for your setup?