Transition your Cannabis plant from Vegetative to Flowering (2024)

So you recently got into growing your own bud, and what an exciting journey it has been! First, you decided to shop strains. Picking out strains is always extremely fun. The sheer amount of variety of cannabis is endless and it can blow your mind. The endless combinations of flavors, aromas, and growing characteristics gives the weed grower always something to chase.

After picking your strain, you popped those seeds, and waited for them to sprout – some did, some didn’t. There’s always a varying degree of success with seeds, and that’s to be expected.

After bringing your seedlings up from a tiny sprout to something more like an actual manageable plant (ya know, something that doesn’t look like it could die at any moment), you took a clone. This is because we always make Mother Plants out of the clones and never from the seeds. You can flower the seedlings, but the result from a clone will always be better. (That is what we have found to be true, as have others).

Next, you continued to grow that plant through it’s vegetative cycle. This is where you start to ask “at what point should I flower this lady?”

We will help you make this assessment with the tips we give in this article.

Determine that you are ready to flower your plant

You first need to determine that you are ready for this plant to flower. And that would include more than just your desire to have some damn bud already!

How do you make this determination? Well, let’s forecast ourselves into the future and see if we like the current situation. Do you want to be dealing with:

• A tall and skinny plant that will yield us very little for all of our time and effort?
• Managing an unmanageable crazy plant?
• The risk pests, disease, mold or mildew?

The obvious answer to all of those is a resounding, “No!” So let’s get to the part where we prevent all of that from happening.

Is your plant the right size for flowering?

The first and most basic consideration when preparing to flower your cannabis plant is the desired size of your plant. The length of your veg cycle will ultimately determine how big your plant becomes.

The flowering period is a fixed period of time, usually 8 to 9 weeks with most strains. No matter how long your plant was in a vegetative growth phase, the it will produce buds and finish flowering in 8 to 9 weeks.

That means that your veg period could be two weeks or six months. It won’t make a difference as to the length of the flowering period, which will remain around 60 days.

What will be different, very different, is the size (and resulting yield) of the plant at the conclusion of flowering. The plant that sat in veg for two weeks will be tiny compared to the one that remained in veg for half the year.

So how do you know how long to maintain the vegetative phase in order to achieve the size that you want?

Plants will Double and Triple in Height during Flower

A good rule of thumb is that your plant will double or triple in size. So take a look at that seedling that is two weeks old and imagine if it were double or triple and that should give you an idea.

Typical veg cycles last anywhere from 4 to 7 weeks

Another metric we can give you is that vegging a plant for four weeks and up through Week 7 or 8 is fairly common. It is much less common to hear of people keeping their plants in veg for much longer than that.

You also don’t hear about people vegging their plants for less than four weeks, mainly because that is not enough time to adequately top your plants and still allow for recovery.

Were you able to accomplish topping and training while in Veg?

So your end-goal for the right size will be the biggest factor in how long your plant stays in a vegetative phase. The next consideration is having enough time to accomplish the critically important tasks of topping and training your vegging plants.

As we’ve explained before, topping allows you to create more tops, which equates to more colas. Additionally, you obtain the benefit of slowing down vertical growth as your plant recovers from the topping, which allows you to train the plant to grow horizontally.

Your plant cannot be topped until it is at least two weeks old. And after topping, your plant will need at least a week to recover before it will continue growing.

So think of it this way: topping your plant adds a week to your veg cycle, because you lose a full week of growth while it is recovering. But in the long run, it will greatly add to the yield of your plant.

If you want to top your plant two or three times during veg, you will need a longer veg cycle, and will have to adjust accordingly.

Making the transition from Vegetative to Flowering period

Now that you understand how to structure the length of time of your vegetative phase, you can start planning your flowering phase.

The first item to tackle is your grow room set up for flowering.

Your flowering space is optimally set-up and ready for the next 8 weeks

In order to properly flower your cannabis, you will need:

• Grow Lights with red spectrum
• Canopy space
• Space to grow vertically
• Bamboo or PVC frame for trellis
• Fans or something to promote air circulation
• Air conditioning or something to control temperature
• Dehumidification
• CO2

In this article, we will focus strictly on the non-equipment related aspects of growing (timing, training, etc) and you can read about equipment set-up in our other articles.

Before transitioning your plants from vegetative to flowering, you should have already topped them. Additionally, you should defoliate them prior to “flipping” so that you are ahead of the crazy and hairy overgrowth that will occur during the post-veg stretch.

Next, you should set up your trellis immediately in your grow space. Your grow space could be the same space where you veg your plants, or it could be a completely different room. Doesn’t matter. The point here is that before you switch to a 12/12 light cycle, you should have your trellis set up.

Trellis is critically important to maximizing a positive outcome in your flower cycle. Trellis will allow you to maximize the canopy square footage. Using trellis will also help you control your plants as they shoot up and stretch.

Setting your Light schedule and Intensity for flowering cannabis

Unless you are using a high-quality LED, you will need a much more powerful light set-up for flowering your cannabis than you used for veg.

When it comes to vegging your plants, you can get away with a very mediocre light set up. But in order to get the plant’s full potential in flower, you need to have a proper flowering light.

The lights with the best historical track record are High Pressure Sodium, such as Gavita, Phantom, and others. However, this conversation is changing as LED technology is evolving.

The point we are making is simply that when you transition from veg to flower, you must use different lights for your 12/12 cycle.

Managing the stress on your plants during the transition

Anything you do to your plants is a form of stress. Cannabis is a hearty and resilient plant. It can take a lot. But just like your body benefits from the stress of exercise, your body still needs adequate recovery in order to prosper.

With Cannabis, it’s all about giving your plant the right amount of stress and recovery.

Topping your plants in veg is a form of stress, and you should allow a week of no stress recovery afterwards.

Similarly, the transition to flower is a new form of stress. Ultimately, the extra darkness is a form of recovery that triggers the blooming. However, that initial switch is a form of stress to be aware of.

We suggest that the week prior to flipping, you do no defoliation or training or anything.

Then, after you have flipped to a 12/12 light cycle, you slowly titrate the wattage of the flowering lights up, from 600 to 1000 watts over the first few weeks of flower (if your lights have the capability).

Maintaining your plants during the flowering period

Once your plants are in flower, you will want to defoliate them at least a couple times, to keep away the chance of mold and mildew that can occur deep in the bush. Maintaining a good hair cut will promote air circulation and also allow light to penetrate deep into the canopy to the lower branches of your plant.

As we’ve written before, the work must be done in the beginning in order to make the finish go smoothly. Growing weed is kind of like being one of the three little pigs: the two pigs that are eager to go play later regret their decision to cut corners and skimp out on the early work.

The pig who delayed gratification until his house was right, ended up being able to actually enjoy the home he built.

Do the hard work in veg, complete all the steps to having a healthy transition from vegetation to flowering, and your end result will be all the more worth it!

To learn more about the flowering period, check out our articles Understanding the Flowering Period of Cannabis, as well as our series A Week by Week Guide to Flowering Cannabis.