While continuing our exploration of cannabis light cycles, we now turn our attention to the concept of skipping the vegetative light cycle and going straight to the flowering light cycle.

Is it possible to begin the 12/12 light cycle immediately after sprouting a seed?

A question that comes up from time to time is whether it’s possible to skip the 18/6 vegetative light cycle and go straight to the 12/12 light cycle after sprouting a seed. In theory, the answer should be “yes.” Theoretically speaking, a marijuana plant will still produce buds if subjected to 12 hours of light and 12 hours of darkness.

But theory and real life practice don’t always match up. The only way to truly know is to test the theory with an experiment.

So we have to decided to test this theory by launching a series on flowering cannabis straight from seed. We have never done this before, so we are excited to see what happens!

How to Grow Marijuana Indoors: The Two Light Cycles You Must Use

As we have explained before, Cannabis is a photoperiod plant, with two distinct photoperiods: the vegetative period and the flowering or bloom period.

The 18/6 Vegetative Light Cycle

The vegetative period is the first of the two stages of the cannabis life cycle. During the vegetative stage, the plants grow taller and bigger, but never bloom. Because they never bloom, they remain immature and capable of being cloned. They can also be trained, by being bent, pruned, topped, and even twisted. In this immature state, they remain pliable and flexible.

The purpose of the vegetative period is to allow the plant to grow, and to train the plant before it begins blooming.

The ideal light cycle for the vegetative period is 18 hours of light, six hours of darkness. However, many other light cycles that can be used, such as 20/4 or simply keeping the lights on 24 hours a day, with no darkness.

The 12/12 Bloom Light Cycle 

In order to make the plants bloom, they must receive much less light than during the vegetative phase. In fact, cannabis plants must receive at least the same amount of darkness as light in order to produce bud. And if they receive more darkness than light, that is fine too.

Why Skip the vegetative stage?

Why would you want to skip the vegetative stage and immediately begin flowering your seedling? This is a question worth asking.

Without having conducted this experiment, we can hypothesize the advantages and disadvantages of skipping the 18/6 light cycle.

Advantages of skipping or shortening the Vegetative Light Cycle

The perceived advantage would be shorter wait time to harvesting flower. If you take a seedling and put it under a 12/12 light cycle, you are only 60 days away from harvesting actual bud. This is a shorter time period than you would get using autoflowers – strains that are specifically bred to flower without having to even change the light cycle.

There are other perceived advantages, such as more harvests per year.

If you are using the same space for veg and flower, then you will also be able to pull down more harvests per year. A lot more.

Disadvantages to skipping the Vegetative Light Cycle

The main disadvantage will be your yield per plant. A 10-day old seedling is not very big, and even if it triples in size during the 12/12 light cycle, it will still not be that big after 60 days. A smaller plant will always yield less bud than a bigger plant of the same pheno.

The other perceived advantage – more harvests per year – only applies if you are growing in a single room for both vegetative and flowering stages. By simply having more grow spaces —  whether rooms or tents – you can get the same number of harvests per year. So this advantage goes away simply by expanding your grow spaces.

There is also the question of whether the quality of bud will be the same without the additional growth that occurs during the vegetative period.

There is only one way to find out.

A video series on using the 12/12 light cycle from seed

We chose to conduct an experiment on this topic. And we documented the entire process. You can read and watch it here.

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