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.

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 two articles on the subject:

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.

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.


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