• Get the scoop! Did defoliating plants in the flowering stage increase yields and THC? Yes, it did! I put together an easy-to-read summary of my recent side-by-side defoliation journal including pictures of the plants while they were growing, a summary of the training I did, the results, tons of bud pictures, and final thoughts!
   
• What should I test next? I've got 4 ideas but I'm also open to new ones. Reply to this email and let us know what you want to see!
   
• This was the second grow I've completed using the HLG 300 R-Spec LED. Check out my review! This grow light has some downsides but the bud quality is out of this world!
   
• This week's trophy pics feature a re-vegging experiment from one of our readers!

The results are in! Have you ever heard of the cannabis flowering stage defoliation technique? It involves strategically removing leaves when the buds are first forming on marijuana plants. The goal is to expose buds to plenty of light and air, which seems to increase overall yields and bud quality on your cannabis plants.

I love doing side-by-side cannabis experiments because I always end up with a ton of awesome weed lol

Did defoliation work?

In this grow journal we discovered that, at least in this first test, the defoliated cannabis plants produced…

• Bigger yields
• More THC in buds (details below)
• Higher quality bud (no larf or airy buds; all buds well developed)

Here’s a quick summary of the final results. The defoliated clones produced bigger yields, more THC, and buds were denser (“tight”).

Defoliation experiment explanation

Clones were grown in identical conditions until the day I put the grow lights on a 12/12 light schedule to initiate the flowering stage. That is when the experiment officially began.

Natural Tent did not receive any defoliation during the flowering stage.

Defoliation Tent received strategic defoliation in the flowering stage. I removed most leaves from the plant on the first day of 12/12 and once more about 3 weeks later.

Let’s skip to the beginning of the flowering stage after the first defoliation.
 

Initiate 12/12 and First Defoliation

This is just before I initiate the flowering stage with a 12/12 light schedule and do the first defoliation. At this point, these plants have been grown in identical conditions.

The “natural tent” (blue tags) just before the switch to 12/12. This is the “control” tent. These plants don’t get touched between now and harvest. All they receive is nutrient water and light.

Here is the “defoliation tent” (white tags) just before the plants get their first defoliation. As you can see, the plants look almost exactly the same because they are clones and have been grown in identical conditions until this point.

Week 0 Defoliation Summary: Lollipop and defoliate plants (I did this the day I switched to 12/12 to initiate the flowering stage)

• Lollipop = remove all leaves at the bottom part of the plant which don’t get light.
• Make sure there are 8 main branches for each plant (cut away the smallest ones)
• Defoliate =
  • Remove all fan leaves bigger than a hand.
  • Remove leaves with stems longer than 3 cm
  • Note: Make sure to keep at least a few leaves at the top of each main branch. 

Here is the “defoliation tent” after getting defoliated and lollipopped according to the instructions above.

Here are the two sets of clones side-by-side.

The defoliation tent will receive one more plucking session in 3 weeks and then all the plants will be left alone until harvest. I wanted to make it so that people could follow along if they wished to, so I kept the training really simple and straightforward without a grower having to make any judgment calls. The plants receive only nutrient water and light for the next 3 weeks.

Second Defoliation (3 weeks since 12/12)

Wow, what a difference in the last 3 weeks! The plants have just been receiving water and nutrients and no other care. Let’s check out how they look.

Here’s the natural tent. It’s a jungle in there. These clones had a surprisingly big flowering stretch (more than doubled in height), which I attribute to the deep red spectrum of the HLG 300 R-spec LEDs.

Here’s the defoliated tent. The lower parts seem a bit more exposed than in the natural tent, but overall the clones look remarkably similar so far. They are about to receive their second and final defoliation.

Week 3 Defoliation Summary: Defoliate one more time.

• Remove all fan leaves with stems longer than 3 cm
• From then on, only remove leaves if they’re covering a bud site or if the plant starts getting so bushy through the middle and bottom that light isn’t making it to the floor

Here are both sets of plants after the second defoliation. Notice on the bottom of the undefolaited plants are in total darkness. However, the plants in the defoliated tent get light all the way to the bottom.

There was no more defoliation after this point. I just gave water and nutrients until the buds were ready to harvest....

"Natural" tent at week 8 of flowering

Defoliation tent at week 8 of flowering

Final results after buds were harvested, dried, cured, and sent to the lab:

Final Thoughts on Flowering Stage Defoliation

So, what do I think about flowering stage defoliation after this test? In many ways, it confirmed what I already suspected. Defoliation seems to increase yields and improve the overall quality/tightness of buds. I had heard growers say that defoliation might increase THC, but it was still a surprise to see that play out in the results for all 3 clones. If all 3 clones produced higher THC in the defoliation tent, that’s not definitive but it is pretty good evidence supporting the idea that defoliation may increase THC percentage.

Defoliation tent was the clear winner in my mind.

• Higher yields
• Higher THC
• Higher quality buds

But why/how does defoliation work? I don’t know for certain, but here is my theory so far....

Keep reading for my final report plus more pictures and information about the grow results!

The Platinum Cookies bud at day 38 of the flowering stage. This strain ended up being the highest-yielding as well as the crowd favorite in smoke reports!

As one experiment finishes, I find myself already thinking about the next one. I was hoping you all might help me decide what to test next!

What do you want to see tested next?

• 3-day dark period to increase THC - I did a very last minute experiment on this a few weeks ago. Although there were several factors that could have affected the results (I harvested half the plant before the dark period, and half afterwards), the initial results were promising. In lab tests, the buds had higher THC after a 3-day dark period. If you all want to test more, I will run a real side-by-side experiment with multiple clones in identical conditions so we can see how a dark period affects the THC in much more controlled conditions.
• Defoliation side-by-side experiment, but with super soil ("just add water" soil) - Today's grow journal had plants grown in coco coir with nutrients added in the water. As a result, the plants had unlimited nutrients at all times. I suspect defoliation would be less effective in a super soil setup and may even reduce yields. That’s because removing leaves also removes a lot of the nutrients stored in the plant. With coco like this grow journal, I’m constantly adding new nutrients in the water so the plant always has as much as it wants. However, when you’re not adding nutrients to the water, there’s a limited amount in the soil. Therefore, I think it may actually reduce yields overall to defoliate because the plant will run out of nutrients in the crucial flowering stage. 
• Test effect of light levels on THC production - This defoliation experiment makes me wonder why defoliation increases the actual THC percentage of buds. I have a hunch that it has something to do with the amount of light getting to the plant. I suspect that more light = more THC (to an extent). But how could I test that? My idea is to use an Apogee light meter to measure how much light is getting to buds in different parts of the tent. Then I will label those buds with their location and light levels. After harvest, I'll test them all against each other. I suspect that the buds with the highest THC in each tent are going to be the ones that are receiving the highest light levels.
• Test LEDs with different spectrums against each other - This grow featured the HLG 300 R-Spec. It seemed like it might be interesting to test it against the HLG 300 Blue spectrum light, just to see how the blue vs red affects plant growth.

Those are just some ideas. Please respond to this email and let me know if any of those sound interesting, or if you have any ideas for future experiements!

Pros of HLG 300 R-Spec

• High-quality buds – sparkly, potent, and dense
• Brings out purple – tends to turn buds and leaves purple, especially the parts of the plant closest to the light (some strains stay green no matter what)
• Fast plant growth – Plants grow fast and healthy with relatively few nutrient deficiencies or light stress compared to some other LEDs.

Cons of HLG 300 R-spec

• Tall stretchy plants – Due to the high amounts of red in the spectrum, plants tend to get tall and grow “stretchy” with a lot of space between nodes. Similar to an HPS or 3k CMH bulb. However, this can be controlled and even used to your advantage with plant training.
• Medium yields – Although I wouldn’t say this light gets low yields (in today's journal each 270W light produced about 10 oz, or about 1 gram/watt), it can’t compete on yields with “high-yield” LED grow lights like the ES300 LED grow light, which gets the best yields per watt of any LED grow light I’ve used so far.

Conclusion: I think of this as my “bud quality” light. These are the buds I bring out for guests.

Read my full review of the HLG 300 R-Spec with more pictures and details about my past grows using the light.

• Seed Supreme – California, United States
• ILGM (I Love Growing Marijuana) – California, United States
• Herbies Seeds – Europe (seemingly out of the UK and Spain) 

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