All of us who grow marijuana are focused on our buds in bloom phase.
And that’s how it’s always been presented: bloom phase. One grow phase, one bloom phase.
But the reality of marijuana flowering is different than that, and when you understand the four-phase secret, you use it to push your plants for max production.
The first thing to recognize is bloom phase is not just one flowering phase that lasts from the time you flip your hydroponics lighting to 12-12 until the time you harvest.
And if you’re growing autoflowering marijuana, bloom phase is the majority phase your plants are in from start to finish.
Autoflowering marijuana plants are only in veg phase for a couple of weeks.
It is far more accurate to say marijuana has bloom phases.
Four of them, to be exact.
What’s really cool is each bloom phase benefits from a different mix of optimized nutrition so you get heavier harvests with more THC.
No longer do we stick with the old school idea that the only nutrients change you make is going from an N-heavy base nutrients in grow phase to a P/K-heavy base nutrients in bloom phase, and throwing in a P/K-heavy bloom booster on top of that.
Turns out there’s a lot more you can do for your plants than that.
For example, some growers gradually decrease grow phase nitrogen-heavy grow base nutrients and gradually phase in their bloom phase base nutrients as they get close to the 12-12 lighting changeover.
And before we get into other details about marijuana’s four flowering phases, let’s acknowledge that the length of the four cannabis flowering phases is determined by genetics, nutrients, and grow room conditions.
If you’re growing Sativa-dominant marijuana strains, you’ll see longer marijuana flowering phases than if you’re growing Indica-dominant strains.
If you have light leaks during your 12-12 dark cycle, incorrect growing conditions, poor lighting, or defective hydroponics nutrients, your blooming marijuana plants won’t mature as rapidly as they could.
Nor will they produce as much THC or weight.
Now, let’s take a closer look at marijuana’s four flowering phases:
Pre-flowering—Even before you switch your lights to 12-12, your marijuana plants may be “showing sex.”
Female primordial flowers, usually with only two white hairs at first, show up at stem junctions (nodes).
With clones, this may happen soon after the root system is well-set. It takes longer for seed-grown cannabis crops.
With seed-grown and cloned plants that have ample root systems, pre-flowers are a clear sign your cannabis plants are ready to go into 12-12 lighting.
Early flowering—Starting a few days after you put your lights to 12-12, pre-flowers begin turning into budding sites and then into “early flowers.”
Fast and generous development of budding sites and early flowers is crucial if you want larger yields and earlier harvests.
You use products like Bud Ignitor that create more budding sites faster.
In early flowering, your buds change as more white hairs develop, and as buds build calyxes, resin glands, and small support leaves.
Near the end of early flowering phase, marijuana early flowers have turned into small, tight, dense clusters that start to fill in the stem internodes.
This phase usually lasts 1-3 weeks after you switch to 12-12 lighting, depending on the genetics of your plants.
In early flowering phase and in the flowering phases after it, providing your marijuana plants “extra” phosphorus, potassium and carbohydrates, sets you up for a heavier, more potent harvest.
Peak flowering—When your buds are well-developed, with increasing numbers and density of resin glands and mature floral structure, you’re in peak flowering.
This marijuana flowering phase is very important…it’s when your marijuana lays on the most THC, other cannabinoids and terpenes, size, and weight.
Problems with temperatures, humidity, pests, diseases, conditions, pH, or hydroponics nutrients during peak marijuana flowering phase sharply reduce your final output.
To make sure your plants get all the nutrients they need, you can use a “ph-Perfect” base nutrient like Sensi Bloom so your crops get more nutrition faster and you don’t have to worry about those friggin’ pH meters.
Peak flowering phase is when you’re most advised to use bloom boosters such as Big Bud or Nirvana.
You also benefit from using carbohydrates products along with resin gland boosters such as Bud Factor X.
Every cannabis strain is different (sometimes every cannabis plant is different even if from the same mother or seeds), but adding the right amounts and ratios of phosphorus and potassium during peak bloom is guaranteed to increase bud size, THC, and value.
Be careful not to let your plant canopy get too warm (above 76F), because excessive heat causes buds to stretch so they’re thin and airy.
Excessive warmth in your plant canopy happens mostly if your plants are too close to grow lights, and/or if your grow room has inadequate ventilation, air conditioning, and air movement.
Monitor your peak flowering buds with a magnifier to track development/condition of your resin THC heads…this is the most accurate way to determine when buds are ready for harvest.
For more information about monitoring marijuana for harvest timing, read this great article here.
Peak bloom is usually the longest phase of your 12-12 cycle, lasting 2-5 weeks for most cannabis strains.
Late Flowering- When your resin glands and bud hairs are starting to deteriorate, but are not so deteriorated that your marijuana is wholly overripe, your plants are in late flowering phase.
This is usually the last 8-14 days before you harvest the plants.
For example, if you’re growing a cannabis strain that has a predicted 8-week flowering time, weeks 6-8 can be described as late flowering phase.
Late bloom stimulants like Overdrive add weight and THC during this phase by pushing your marijuana plants to add more bud development at a time most growers don’t think their cannabis plants are able to deliver more weight and THC.
After Overdrive, stop using all nutrients and flush your plants just before harvest to get rid of pollutants and stored fertilizer salts.
I get it that realizing the 12-12 cycle has four marijuana flowering phases instead of one long phase is more complex than the old-school idea.
But just like we humans have distinct growth phases (infant, toddler, child, adolescent, young adult, middle-aged adult, elderly adult, deceased), marijuana does too.
And we all know that dietary inputs and other factors need to be adjusted to make the most of each growth phase, whether it’s for humans or marijuana plants.
In practice, this means you now feed your marijuana plants a varied 12-12 light cycle nutrients diet tailored to make the most out of each flowering phase.
Instead of dumping a simplistic formula of “bloom” base nutrients and a P-heavy bloom booster in for the entire 12-12 cycle, you provide smarter nutrition tailored to building the most-productive cannabis flowering structure in each of the four phases.
The result? More resin glands, earlier maturation, larger buds, and more value from every marijuana plant you grow.
Ok, so take a look at the photo of my Headband plant that accompanies this article. What marijuana flowering phase is the Headband plant in?
If you said “very early flowering,” you are right on the money! This marijuana plant needs at least 17 or more days before it hits peak flowering phase.