Chapter 21

FLOWER Phase Instructions

You easily initiate transitioning to the FLOWER phase by changing your light cycle to 12 hours ON and 12 hours OFF (12 / 12) using a light timer.

In 1 – 2 weeks after the light cycle was switched, flowers begin forming with white hair like structures called pistils at what is called a bud site. As soon as you can see the flowers developing, then you begin to count the weeks of FLOWER. For example, FLOWER week 1, FLOWER week 2, FLOWER week 3, so on and so forth. Don’t count FLOWER weeks until you see flowers. Don’t count FLOWER weeks when you flip to 12/12, instead wait until flowers are observed.

FLOWER phase is all about flowers growing. There’s not much to do.

Within FLOWER phase, there is early-FLOWER, mid-FLOWER, and late-FLOWER.

During early FLOWER, the flowers begin forming on what growers like to call bud sites. Flowers start bulking up and developing white sparkling trichomes in mid-FLOWER. In late-FLOWER they’ll be the most aromatic, and they smell the strongest in their morning hours and at night before lights out.

You’ll be surprised at how drastic the flowers visually transform on a weekly basis. Flower week 2 looks so much different than Flower week 4, and the said can be said of Flower week 4 compared to Flower week 6, 7, or 8. To make sure you see the transformation from a weekly vantage point, just take a picture or video every 7 days to track the transformation on your phone. During mid to late FLOWER phase, it is normal for leaves to change from green to yellow and brown. Or if you’re lucky, they might fade into shades of red, purple, orange, etc.

Some strains will still grow and stretch in the FLOWER phase, like Kushman’s Grape Ape. But for the most part, after FLOWER weeks 2 or 3, most strains stop growing tall and focus exclusively on flower growth.


Overall in FLOWER phase, there’s not too much to do.

All you need to do in FLOWER phase is fertilize properly, water properly, defoliate just a little, and manage the temperature and humidity as best as you can. Plus, you’ll do some pest control sprays before the flowers get developed fully. In FLOWER phase, water your plants as needed, however you can expect your plants to need more frequent watering sessions than in VEG phase. Don’t overwater though. It would be better to under water than to water too much.

Each week, the flowers transform and take on a quite distinctive appearance. They’ll bulk up especially in late FLOWER phase, so don’t be disappointed if the flowers aren’t as big as you had hoped during FLOWER week 4. The sticky, frosty, smelly sparkly substance all over the flowers and sugar leaves are called trichomes. Trichomes are full of cannabinoids and terpenes, which are the compounds that cause the fragrances and influence the effects you feel.

Most home growers understandably stop using pest control sprays after FLOWER week 2. No one wants to negatively affect the taste of their home grown flowers. Many pest control sprays claim you can use them “up to day of harvest,” but cannabis growers who smoking their end product aren’t interested. Even though many home growers stop pest control sprays all together in FLOWER week 2 or 3, there is still a way to use them. You can read more about this grow technique coming up.

To smell your flowers properly, do a sniff test simply by rubbing your fingers back and forth on a section of the stem right in between a couple buds / flowers. Then smell your fingers. Do not grab or pinch the flowers / buds themselves. Instead put your fingers on the stalk or stem in between flowers / buds and rub there. Be forewarned, the first time you get a whiff of fresh strong terpenes, you might literally want to shout for joy or sing. Do it! If it smells strong, then you’ll know your cannabis flowers are in ideal shape. You can start your sniff tests in FLOWER week 3 or 4 when you see plenty of sparkling trichomes.

If there’s never a strong smell, you might have bad or weak cannabis genetics, or you could have a plant disease like Hop Latent Viroid. Hop Latent Viroid is a modern plant disease that causes plants to produce very little trichomes, weak branches, and poor yields. However, don’t rule out overwatering for lack of fragrance, if that’s an issue. Overwatering does not help cannabis flowers thrive. It really hurts them. If you’ve been overwatering, your flowers might not get real smelly.

Towards the end of FLOWER phase, you can begin to assess the trichomes on the flowers (not the leaves) with a jewelers scope to determine when a plant is ripe, mature, and ready to harvest.


Here’s what to do in FLOWER phase –

1. Change the light cycle to 12 hours ON / 12 hours OFF.

2. Feed the soil w/ Dr. Earth’s “Flower Girl” topdressing fertilizer.

3. Water plants as needed.

4. Apply pest control (ideally up until FLOWER week 2 or 3).

5. Defoliate the top of your canopy in early-FLOWER to allow light penetration.

6. Ensure temperature and humidity are in the acceptable range. (50 – 60% RH is the ideal humidity range and 70 – 80 F is the ideal temperature range.)

7. Assess trichomes with a jewelers scope to determine when to harvest and chop plants down.


If it’s very hot inside and hard to keep the temperatures in your grow tent down, then you should make sure the LED light is turned down if possible. High heat over 80 F can evaporate and diminish terpenes. That’s not good. Another solution to heat issues is running LED grow lights at night instead of during the heat of the day. Or, use LEDs that don’t get hot. Some do and some do not get hot.

Be careful with your open vents at the bottom of the tent when your grow tent is in a well lit room during FLOWER phase. In a very dimly lit room, I would not be concerned about light penetrating the plants from opened vents however. But if it’s a bright room, keep the vents closed. Having closed vents may cause tent to suction in on itself. That’s ok and it is commonplace.


The Green Carpet Growing FLOWER phase timeline:

12/12 TRANSITION week – Fertilize w/ Dr. Earth’s “Flower Girl” Topdressing Fertilizer
FLOWER week 1 – Pest prevention spray
FLOWER week 2 – Defoliate and Fertilize w/ Dr. Earth’s “Flower Girl” Topdressing Fertilizer
FLOWER week 3 – Pest prevention spray 
FLOWER week 4 – Fertilize w/ Dr. Earth’s “Flower Girl” Topdressing Fertilizer
FLOWER week 5
FLOWER week 6 – Fertilize w/ Dr. Earth’s “Flower Girl” Topdressing Fertilizer
FLOWER week 7 – Asses trichomes
FLOWER week 8 – Assess trichomes
FLOWER week 9 – Assess trichomes


Defoliate in FLOWER week 2 after the bud sites have begun flowering. If you see leaves blocking flowers from the light above, try to move them, but if that doesn’t work, remove them. It’s important to expose the top canopy of your flowers to the light and not allow leaves to block any of your tops. 

How do you know when a cannabis plant in FLOWER phase is ready to be harvested? Other ways of asking this question could be: how do you know when a cannabis plant is ripe? Or how do you know when a cannabis plant is mature? 

For starters, if the trichomes observed with the jeweler scope are clear and transparent, then the cannabis plant is not ready to be harvested, nor is it ripe or mature. Milky white is the color that means the trichomes are ripe, mature and ready. The last colors you might see are orange, red, or brown. These dark colored trichomes indicate the plant’s THC has converted to CBN, a different cannabinoid all together that is known to make most people feel ultra-drowsy. “Sleepy time weed” is made by overripening any cannabis strain. Try it and see for yourself! 

Get ready for the next and final phase of growing: HARVEST phase. HARVEST phase consists of drying and then curing your weed. As soon as you have dried cannabis however, feel free to smoke it if you’re, you know, all out! It won’t be as smooth as if it were cured for a couple weeks, but it should taste great and be relatively smooth. If it tastes harsh, it might not be totally dry. You’re about learn the in’s and out’s of harvesting, so head to the final chapter. 


Marc Eden’s DIY Cannabis Cultivation Book For Beginners
Published by Green Carpet Growing, Inc.
San Diego, CA 92103
© 2021 Green Carpet Growing, Inc
All Rights Reserved

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