Growing Weed 12 12 From Seed


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After switching from a vegetative light cycle to a 12 on, 12 off flowering cycle, marijuana plants will begin producing pre-flowers in Week 3 and buds in Week 5 If you're looking to maximize your yields but you are limited on space, maybe it's time to switch from your… by twistedpurple

How long after switching to 12/12 until plants start flowering?

So you’ve gotten in the game of growing marijuana and you’ve been successful so far. You’ve gotten your seedlings to take root, you’ve grown them through the vegetative stage to a sizeable plant. And you’ve now flipped to 12/12 light cycle to finish the process.

The thing about growing weed when you’ve never done it before is that each week is like a mystery. You’re not quite sure what to expect. And when something new develops, it’s this giant surprise that has you scrambling, trying to figure out what to do next.

This happens whether it’s discovering that you have a problem, like powdery mildew, or allowing your plant to grow tall and skinny and then realizing that’s why you have next to no yield.

Learning how to Grow Weed is a practice in Trial & Error

The first few rounds of growing are hard. It’s truly trial and error. But if you can have a guide, such as this blog, that prescribes a set of general guidelines and expectations, the journey is so much more fun. That’s what happens when you remove unnecessary bouts of stress and self-doubt.

So let’s jump into some of the specifics on what to expect when you start the flowering cycle.

We’ve covered the foundational concepts in our article Understanding the Flowering Period of Cannabis. And that article will absolutely get you a clear understanding of the two photoperiods.

But once you start growing, you quickly realize how theory alone is not enough to get you through solving many of the day to day situations.

A big part of the mystery is just knowing what to expect week to week. So that is why we have created a Week-By-Week Guide, with photos and video, to show specifically what the plants actually look like each week.

In this article, let’s specifically answer the question of when to start expecting bud after flipping to the 12/12 light cycle.

What is the 12/12 light cycle for marijuana growth?

The 12/12 light cycle refers to 12 hours on, 12 hours off, with regard to indoor lighting. This light cycle is necessary to trigger the flowering stage of cannabis. But first, let’s back up and re-examine the light cycle used to get here.

To quickly summarize how to grow marijuana, after you sprout your seed, you must grow it up through what is known as the Vegetative stage. This phase mimics the summer where the is more than 15 hours of sunlight per day. The days are long and the nights are short.

When growing indoors, that means you keep the lights on longer than you keep them off. This causes the plant to grow, but prevents it from blooming.

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The reason you do not want the plant to bloom immediately, and produce bud, is that you want the plant to be a certain size, capable of actually producing big buds.

So you keep the lights on for 18 hours a day, off 6 hours, to speed up the growth and get your plant to the right size. This usually takes four to eight weeks, depending on how big you want your plant to get.

When you are ready to start producing bud, you must then switch the light cycle. If you are wondering when should you stop the vegetative light cycle and switch to a 12/12 flowering light cycle, we have written some guidelines for you to consider.

Making the Switch from a Vegetative light cycle to a Flowering Light Cycle

Once you’ve made the switch to a 12/12 light cycle, you will not immediately see buds. Do not worry. Nothing is wrong. Your plant will need some time to adjust to the new cycle before it will begin producing flowers (buds).

In this article, we will tackle the issue of when you can expect to start seeing buds, how big they should be at each stage, and how long to flower your plants. Once you know what to expect and when to expect it, flowering cannabis becomes less a guessing game of mystery and self-doubt and more of what it should be, an enjoyable ride with a clear destination.

Marijuana Plants will not produce buds during the first few weeks of the 12/12 light cycle

If you have just switched to the 12 on, 12 off light cycle, do not expect to see any bud sites during the first couple of weeks. During Week 1 and Week 2, the plants are simply adjusting the additional darkness they are receiving. This extra amount of darkness allows them to recover, which sends them through an intense growth spurt that lasts several weeks. This growth spurt is known as the post-vegetative stretch.

During the first two weeks of the flowering light cycle, your plants will look like they are still in veg, except they will be growing out of control. Check out our resources on managing the stretch during this time, as taking control of the plant’s chaotic growth is absolutely critical to getting good results later in the flowering stage.

Marijuana Plants will begin to form pre-flower bud sites in Week 3

If you check out our Week-by-Week Guide to Flowering Cannabis Indoors, then you will see the emergence of pre-flower bud sites in Week 3. These sites will sprout long white pistils (i.e. the “hairs” you are used to seeing).

This photo shows the development of the bud sites during Week 4

The plants will see be deep into the post-vegetative stretch, still resembling stretching veg plants. But these bud sites let you know that the plant is maturing and making its way through the flowering phase.

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Marijuana Plants will show more advanced development in Week 5 of Flowering

It is in Week 5 that your plants will really begin to show developed bud sites. At this point, the vegetative growth has ceased and only bud development growth is taking place.

This maturity growth will only increase as you progress through flower. During Week 6, the aroma will be so strong and the plants will be looking so beautiful. During Weeks 7 and 8, you will want to get your camera out to capture the beauty and elegance of your live cannabis plants.


So in summary, you will not see buds for the first three weeks. During the third week, pre-flower sites will emerge, but will not fill in until Week 4. You will notice distinct development in Week 5 that will only increase as the plants progress through the remainder of flower.

Maximize Cannabis Yields With The 12/12 From Seed Method

If you’re looking to maximize your yields but you are limited on space, maybe it’s time to switch from your traditional cultivation techniques to the 12/12 From Seed method. Instead of cultivating from a clone, waiting through weeks of the vegetative stage, and growing plants that take up way too much room, the 12/12 from seed method produces high yields and maximizes your time, space and money.

Traditional indoor cultivation systems that run from clones maintain vegetative stage that lasts anywhere from 2-4 weeks, sometimes longer. The vegetative stage is maintained using an 18-24 hour light cycle, which prevents the cannabis plants from flowering. The 12/12 from seed method takes a different approach. By starting your garden from seed in stead of clone, you avoid potential problems like pests. By implementing a 12/12 light cycle from germination, you end up with a lean, dense plant, and by elimination of the veg stage, you will be able to harvest up to seven times a year. This makes it an ideal method of cultivation for anyone pressed for time and space.


While growing cannabis from clones may seem like a quick and easy way to get started, they have their fair share of drawbacks. First off when you grow from a clone, you are limited whatever selection the local clone shop has, as you can’t ship clones through the post. Buying from a respected seed bank gives you selection and confidence that what you are buying is actually what you are getting. Next there is the risk of contamination. Grows are affected by pests and mildew not because they are inherit in the plant. They are brought in from the outside, often on clones purchased from contaminated sources. It’s just not worth taking the chance. Starting with quality seeds is a fundamental part of the 12/12 from seed method.


The vegetative stage is the early stage of a cannabis plant’s life. It is during this time that the fledgling plants are fed a high nutrient regimen and are kept under either 18 or 24 hour light cycles to prevent flowering. This vegetative stage is a time when young plants grow into a rigid framework on which the heavy cannabis buds can sit. High levels of nitrogen are needed to reinforce cell walls, strengthening branches, and creating a lattice of limbs strong enough to support the weight of the incoming fruit. The 12/12 from seed system of cultivation does away with this entirely focusing the light’s energy into a single robust cola surrounding the center stalk.

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Once your seeds start to germinate, going right to a 12/12 light cycle will forever change how your plants will grow. By removing the four week veg stage, you force the plant to grow a single dense cola around the central stalk, as the many branches of the plant have not had time to form. This causes flowering to being almost immediately. The central shaft will be surrounded by only a few smaller branches close to the base. The end result is 85-90 percent of the budding occurs in the single central cola.


High yields in small spaces is one of the primary benefits of the 12/12 from seed method of cultivation. By design, plants grown in the 12/12 method start flowering from day one. This causes flower growth to follow a very consistent pattern of short, tight, single cola plants, with few smaller branches. This allows the maximum amount of energy from your lighting system to be focused into the single central cola. This eliminates most lower branches and the space they take up along with them. This is ideal for those who don’t have much space to play with.

In eliminating the four weeks or more of vegetative time, you are able squeeze in more harvests per year. Using the 12/12 from seed method growers have been able to harvest as many as six or seven times each year. More plants per square foot plus more harvests per year equals an opportunity to truly maximize the amount of cannabis you can produce in even the smallest of spaces.

Switching to the 12/12 from seed method of cultivation produces the same dense, high THC rich nuggets of its traditional counterpart, however, is designed for those looking to maximize yields in tight spaces. By eliminating the vegetative stage, you are able to squeeze in a few extra harvests every year which will save you time and money in the long run.

Author – Cory Hughes / Twisted Purple Media.
Twisted Purple Media is a cannabis content provider and original author of this article.
Twisted Purple Media holds the legal right to display or reproduce this content.
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