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Old 12-16-2018, 05:48 PM
Marcus_in_the_Darkus's Avatar
Marcus_in_the_Darkus Marcus_in_the_Darkus is offline
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Join Date: Mar 2017
Location: Legal in Massachusetts
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I appreciate the feedback, compadres. Herewith some responses to the points made so far...

Originally Posted by beauthebulldog View Post
Low light is limiting the energy going into the plant. You said it yourself, the yield will suck. Vegging at 12/12 with the light on for an hour or so in the middle of the dark period works well to control stretch in sat doms.
Thanks, BTB. I've read about the energy savings of vegging short-day plants in by flashing the lights midway through the dark period, but didn't know it could control stretch. I think that's moot in my situation though because I flower rooted clones without any veg time and they still stretch out of control. Also, the idea behind using low light is to intentionally limit the energy the plant receives to control root mass and, thereby, stretch.

Originally Posted by musashi View Post
What lights are you using i.e. spectrum? 2k, 4k, or 6k?

I use 6k bulbs, trim the bottoms, keep the plants off to the side, min. nutrient, higher humidity, temps in the 70's, trellis them, and leave em alone. Still plan on 3x stretch during flower.
Great advice, brother Musashi. I use LED COBS, half are 3000 K and the other half are 3500 K. Next set of lights I build will probably use 5000 K COBs, but probably not for this next grow. I didn't trim bottoms last time and I will going forward. A 3X stretch would be acceptable, but I think my last batch of sativas stretched something like 8X.

Originally Posted by Big Sur View Post
In my experience growing, it is not too much light that creates stretch, its too much HEAT. Keep them under 80 deg. F. to reduce stretch. I grow outdoors mostly and the more sun, the less they need to stretch. The sun produces way more light than you are typically going to get indoors with a broader spectrum. Not enough light will also create stretch, especially in seedlings.
Hey, Big Sur! Keeping the heat down is NOT a problem in New England until June or July, so heat isn't an issue. But the limited stretch of the light-starved plant I'm currently growing proves that not enough light can actually control stretch.

Originally Posted by n2ishun View Post
Let the tops of the plant grow above the light into a shaded area above the reflector of whatever sort you have.
They stone cold shut down stretch when you do this.
The plant doesn't want to be in the shade.......use that to your advantage.
That's good information. So I could set my lights a little below the intended top of my canopy, let the apical flowers grow through and above the fixture, and then presumably raise the lights after the stretch is over. That sounds like a doable plan.

Originally Posted by Elmer Bud View Post
Less light = less vigour .
To help structure .

More blue and no shading .
Red spectrum causes stretch . MH or TL 5 for veg .

Lolipop so the plants don`t sense infra red on the lower leaves .
Top several times .

Still gonna stretch during flower though .
Hey EB. I was thinking less light, less vigor during root development, essentially giving the same result as using smaller pots. I don't really like to lollipop because I want to observe the structure of the natural plant as much as I can while pheno hunting. The thing that appeals to me about light deprivation is it can "bonsai" the plant to an extent, so that it can be flowered without training to observe the natural branching and bud structure.

Originally Posted by CannaFish View Post
I can only add one thing to the convo. I read some of the gw pharma trials on growing glasshouse plants in the UK. I think this stood out as one of the most important points to growers...

It suggests that "the irradiance conditions on the very beginning of flowering have the greatest potential impact on the final yield." It also seems to not just affect yield but potency as well.

Pages 120-126
Wow, Fish, thanks for bringing the tech! I need to read that article in full and better understand how they set up the study, but I think this is the money shot:

I missed the part about lower potency potential from lower light levels during the stretch. Where was that suggested?

My interpretation is that root mass develops rapidly at the onset of flowering, especially in sativas, where the stretch and root mass growth go hand in hand. Therefore less light = less root mass = smaller plant = lower yields. So my idea is to reduce light over some portion of the first 6 weeks of flowering to control the root mass and the ultimate size of the plant.

Based on all the good information that you have shared, the measures I could take to better control stretch in my situation, include:
  • Use smaller pots. My 4-gallon pots simply hold too much root mass and plants that grow too big for my 4x4 tent setup. I'm thinking of these 3.5 gallon square pots, which would make fine hempy buckets. Only a little smaller than my current 4-gal setup, but it would help. Plus I'd pick up a couple inches of grow height.
  • Use 5000 K lights. I might build these and sell my current setup.
  • Lower lights to ~6" below ideal canopy height at the flip, let the apical buds grow above the lights and reset lights to final height after ~6 weeks.
  • Lower light intensity during a portion of early flowering. Maybe 50% power for the first two weeks then ramp it up each week to 100% power at week 6.
  • Reduce feedings.
  • Trim bottom of plant.

I'm not sure what combination of the above I'll try, but I am still considering light deprivation during early flower. I don't care if I lose a little yield, but I don't want to lose potency. Ideally I want to control the size of these plants without training to ~1.2 m tall to the tip of the apical buds. I'll post up a pic later of my prototype light deprived punto roko x mangobiche. She's a beauty, and she's the perfect size for an indoor sativa pheno hunt.

Last edited by Marcus_in_the_Darkus; 12-16-2018 at 05:55 PM.
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