The Flowering Stage of Cannabis

From the Stretch to Harvest

Marijuana plants mid way through the flowering stage

Hey there and welcome (back) to Free The Tree!
In this series of the cycle of life of WeedΒ we’re going to cover the Flowering stage. This is one exciting part of her life!
You won’t see her grow as much is size anymore, but her flower… oh her flowers will develop oh so nicely, starting from small pistils to buddlets and then full grow flowers, by the last stage you won’t even recognize them anymore ^^.
(Take some pics to compare the evolution! And if you want come share them with the FT community πŸ˜‰ )

The Flowering Stage – Table of Content

  1. Characteristics of the flowering stage (coming soon)
  2. PK – Flowering Stage Nutrients
  3. The Stretch
  4. Early Flowering Stage
  5. Trichome Appearance
  6. Late Flowering Stage
  7. Flushing your plants

Let’s get into it

PK – The two main nutrients of the Flowering Stage

The main difference with the Vegetative Stage NutrientsΒ is the lack of Nitrogen.
Since the plant mainly uses Nitrogen in order to create new sections of the plant, now that she’s focusing on the developing her flowers there’s no need for it. For that, she’s going to need Phosphorous and Potassium, and a good amount of them.

Now just like during the vegetative stage, if you’re looking for a precise table of how much to feed your plant we can’t do so.. It depends on the type of nutrient and your strain.
Our advice is the same, follow the indications given by the manufacturer but reduce the levels a little. If your plant shows some deficiencies (apart from Nitrogen), add a little more nutrients in there.

Last but not least, don’t forget to flush your plants during the 2 last weeks of the flowering stage! If you don’t do so the buds will still be full of nutrients which will ruin their taste.. Would be too bad to waste your harvest just because you forgot to stop giving them Nutrients at the end of the cycle.

Now lets look closer to each nutrient and their use.

How does Cannabis use Phosphorus (P) during the Flowering Stage

Phosphorous basically has the same use during the Vegetative and Flowering stage, with a couple exceptions.

Once the stretch starts the plant will redirect it from the root growth to the blooming of the flowers.

Apart from that, it keeps on being part of the formation of the oils, sugars and starches and the photosynthesis process,all of which is necessary for the plant to thrive.

How does Marijuana use of Potassium (K) during the Flowering Stage

Potassium basically acts in the same way during the whole life of your Marijuana Plant.
It’s responsible mainly for 3 things during the whole life cycle:

  • Encouraging the uptake of water, which your plant needs whether vegetating or flowering.
  • Increasing the resistance to diseases.
  • Helping the plant make better use of the light and air available.

On top of that, when Cannabis gets to the flowering stage, Potassium is essential for the development of the flowers.

Recap of PK use in Weed

Nutrients Use in Cannabis
Potassium (K)
  • Encorages uptake of water
  • Essential for the development of flowers
  • Increases resistance to diseases
  • Help plants regulate and make better use of light and air (photosynthesis and respiration)
Phosphorous (P)
  • Encourages flower blooming
  • Essential part of the photosynthesis process
  • Involved in the formation of sugars, starches and all oils.
  • Helps with the transformation of solar energy to chemical energy (photosynthesis)

The Stretch – Final Growth and Flowering sites

What people call “the stretch” is the ~2 weeks after switching light periods, generally 18/6 to 12/12. During these 2 weeks your plant will have a very strong growth, up to 200% for the most extreme strains. You will also see the bud sites appear, starting with pistils and growing into small budlets.

By the end of the stretch your plant will have fully stopped vegetative growth and will have formed all her bud locations.
If you went for a scrog, this can also be a good time to get rid of the weak branches that don’t look too promising.

Here’s the evolution of one of our own during the stretch, as always you can click on the image to see the full version.

Stretch started a couple days agoΒ 

Vegetative growth almost over, pistils forming

Mid way through the Stretch – Pistils starting to show

Stretch Has ended, all the bud sites have formed

What are the characteristics ofΒ Marijuana’s Stretch stage:

Stretch What you will see
Β How to start it Change you light pattern from 18/6 cycle to 12/12 cycles.
Growth Very rapid! Depending on Sativa or Indica strains it can vary from 70% to… over 200%!
Sativa’s grow the most during this time, so get a meter out and start measuring to max hight in your space
Length in time 2 weeks long
Humidity 40% to 50%
Temperature Around ~ 25Β°C. Be sure to measure at the level of your Apex’s!
Nutrients Reduce the levels of Nitrogen given over time
Increase the levels of Potassium and Phosphorus.
Light cycle 12hours of light and 12 hours of night
Branch and leaf density Β The Apex and branches will take in high very rapidly, keep an eye out in 2 weeks time you won’t recognise her anymore!
The leaf mass will keep growing the first half of the stretch, after which the focus will go on the buds.

Early Flowering Stage

Once your plants have finished stretching and her budlets are well formed she will solely focus on developing those buds.
You’ll see them grow and totally change during the following weeks, the closer to the harvest the denser they’re going to look πŸ™‚
During this phase you won’t really see any trichomes, or just very few, since the glands haven’t developed yet. This is normal so no worries, within the next days/weeks you’ll see them start to come in.

Budlets trans

Budlets growing on the plant

Apex bud developing

bud and pistils fattening up

Pistils developing and bud starting to fatten

Trichome Appearance and Development

A couple weeks into the flowering stage you’ll start noticing some hairy/dusty looking things on the pistils and leaves that surround them, say hello to the Trichomes!
At this point these trichomes aren’t fully formed yet and still totally clear. They don’t contain any THC nor CBD, but in time they will πŸ™‚
For the following days and weeks she will keep on developing her buds.
On the side of the trichomes they will finish growing, developing a ball shape at their end after which, if you look through a little micro-scope, they will start turning milky and then golden/brown.
Basically, when they’re milky they contain the maximum levels of THC, after which the glands start to die and the THC is replaced by CBD.

Nutrient wise you might want to increase PK solutions a little to give her a boost, without overdoing it. This will increase her flower production, meaning bigger buds at harvest! But if you over do it she might get Nutrient burn which creates leaf mass loss, meaning less photo-synthesis which will lead to less energy, thus smaller buds, so be careful!

focus on 2 leaves with trichomes growing

2 Leaves with Trichomes developing

Trichomes Starting to appear on plant

Bud covered with trichomes

Apex starting to be covered with Thrichomes

Stages in the development of Trichomes

Β Trichome State Description
Unformed or Clear
  • The Trichomes isn’t fully developed yet. The stalk is still growing.
  • The head of the trichome isn’t formed or isn’t perfectly round yet.
  • No THC or CBD production has started.
Some are Clear, some are Milky
  • THC production has started in some Thricomes.
  • The levels of THC aren’t at their highest.
  • Not ready to harvest.
Mostly or all Milky
  • Β THC levels are at their highest.
  • If you’re aiming for an very upper type effect this is the window for harvest.
Mostly milky and some are turning golden/amber
  • THC glands are starting to deteriorate.
  • THC levels are starting to reduce.
  • CBD levels are starting to increase.
  • If you’re looking for that mildly upper high this is the time to harvest.
Mostly or all golden/amber
  • THC Glands have fully deteriorated.
  • CBD levels are at their highest and THC levels at their lowest.
  • If you’re looking for more of a chill/”couch potato” high this is when you want to harvest.
Check out our full guide on Trichomes for more!

Late Flowering Stage

What we decided to call the “late flowering stage” starts when your pistils start to turn brown for the first time.
At this point, the flower is fully formed, you’ll have a nice and tasty smell within the room and really, you’ll just want to harvest them they look so tasty, but don’t!!
By harvesting too early you can lose up to 50% of your harvest.. which would suck, you definitely put to much effort in them no? The buds are fully formed, they haven’t finished fattening up hehe.

Marijuana pistils are known to “go brown” 2 or 3 times during the flowering stage. You’ll see the tips of the buds kind of close while the pistil dries up, totally normal. Within a couple days you will see new pistils come back out and grow, increasing the size of your buds.

Depending on the strain of cannabis, this phase can go on for a couple weeks, you’ll want to observe the evolution of the trichomes to decide when to start flushing your plants before harvest.

Pistils are not the right way to define the moment to harvest, observe the trichomes for that.

first pistils starting to turn brown

First round of browning pistils
(Don’t harvest here!)

Pistils of the plant have turned to a brown color

Focus on tip of the plant – All brown pistils & closed up bud

White pistils coming out of the bud

White pistils starting to grow back out of the bud

Flushing your Cannabis plants

At least 2 weeks before harvesting you want to start flushing your plants. What do we mean by flushing? At each watering from this point on you will stop giving them any nutrients.
This will force the plant to extract all the needed nutrients, like Nitrogen, from the buds and leaves in order to keep living. You might think this is counter productive, but all those nutrients in the buds will waste your harvest.
Whether it’s taste or health wise, all these nutrients need to be extracted from the flowers leaving only the cannabinoΓ―d that are produced by your strain.

This means that while observing the Trichomes you must think ahead in order to start flushing your plants in time.
If you’re hesitating start a little earlier than later, less nutrients does mean less weight, but also tastier buds πŸ™‚

Flushing started a couple days ago, no signs of deficiency yet

Flushing has just started, no signs of any deficiency

about a week into flushing, start of nitrogen deficiency

Half way through flushing, firsts signs of Nitrogen Deficiency

full nitrogen deficiency, almost all the main leaves are dead

Ready for Harvest – Full on Nitrogen Deficiency

As you can see, by the end of the flush the plant has extracted all the nutrients (especially Nitrogen, but not only) from the main leaves.
It’s not visible, but she did the same within the flowers, at the same time her trichomes are all milky and starting to brown, let’s get to harvesting!

We will cover that in the next article of the series, coming soon!

Until then, be safe and grow easy!

Flowering Stage of Cannabis – Frequently Asked Questions

Nitrogen Deficiency while flowering

Nitrogen deficiency can/will generally pop up at 2 moments of the flowering stage, during the stretch and the late flowering, in the first case it’s not great, the second it’s wanted.

Nitrogen deficiency during the Stretch

Since your plant is growing so much during the 2 first weeks of the flowering stage (aka the stretch) she needs a large amount of nutrients. To prevent any issues don’t hesitate to boost your NP nutrients before getting it started.

If you’ve already started the stretch things are a bit more complicated… As we’ve seen further up Cannabis reduces her intake of nitrogen once the flowering has started making it a bit touchy but not a done deal, you can

  • Keep adding some Nitrogen to your feed
  • Foliar feed, since it’s a mobile nutrient the plant will intake it.
  • Don’t worry too much if it’s only impacting a couple bottom leaves.

Nitrogen deficiency at the end of the flowering stage

The 2 last weeks of the flowering stage having Nitrogen deficiency is positive, even wanted which is why growers flush the plants during the 2 final weeks of the flowering stage.
If you do not do this the buds won’t be as tasty, you’ll have a weird (nitrogen) taste, although it will weigh more.

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