How Can I Limit Autoflower Rapid Stretch

I only use ILGM seeds.

I have a small 24"X24"X60" inch tent elevated 16 inches with a 20 inch round X 16 inch deep self-watering grow tub inserted in a 20 inch round hole in the bottom of the tent floor. This adds 16" + 60" = 76 total inch. Grow tub means 4 inch black drain pipe covering bottom of tub with 1" vertical watering pipe, covered in weed mat and filled with Ocean Forest 50% and Happy Frog coir 50%. Tub holds 3 gallons in reservoir. Plus I’m using an automatic watering top-side at:
During Vegetation 30 seconds day (until plants reach moist dirt)
During Flowering watering 60 seconds a day
365 Day C02 bag
Grow Dots - light dose
HLG 100 LED Light 20 inches away from plants (3x3 footprint)
Using a Tablespoon of Veg and/or Bloom fertilizer per gallon
24 hour grow music, mostly classical, Schumann resonance, 528 mhz, etc.

Here’s my quandary:

My last grow in this tub gave me 3 pants with autoflower heights of AK47 is 26” and Super Skunk is 24” and Sour Diesel 19” which was picture perfect in this tent. I was very happy with this grow. This grow got the C02 bag in week 5 after Vegetation going into Flower. Key point.

The very next grow in the same tub and conditions: Afghan 57+ inches, Sour Diesel is 55+ inches, Wedding Cake is 15 inches. 2 plants double in size from last grow shading the Wedding Cake Auto. I had to move the lights outside the tent. Leaving the tent door open and 2 HLG 100 LEDs shining into the tent vertically. I have a tent full of buds.

I don’t ever want another 4 foot + plant. I want 30 inch maximum height.

I suspect the C02 in the second grow and lite grow dots are responsible for the double rapid growth stretch.

But in order to make sure this 5 ft stretch never happens again I plan to do away with the grow tub and limit root ball to only 1 gallon fabric pots using the auto watering (1/4 inch tube) 30 second day during Veg and 60 seconds day in Flower.

I’ve even considered leaving the C02 out during Vegetation and dropping the extra grow dots.

If I ever grow Feminized plants again it will be in half gallon pots or dixie cups.

I won’t put 3 plants in the 20 inch grow tub ever again. If 2 take off and stretch they will completely cover a 3rd plant that will be stunted. I need the ability to pull and move a plant as needed. I’m going back to small fabric pots.

Any other ideas out there about how to keep final height at 30 inches or less?


Adding light to your grow space will reduce stretch. Genetics plays a huge role as well. That 100 watt light is not enough to properly flower one plant, much less several.

FYI CO² bags do absolutely nothing for you. Using it effectively requires a closed loop system with elaborate environmental controls and an insane amount of light.

Autos are tough to train but my first go-to is to run a SCROG. That means photoperiod as autos don’t respond well to high stress training.


Thanks. This eliminates the possibility in my mind that the C02 is causing the stretch.

This leaves the grow dot lite dose as a possible culprit.

And possibly the 100 watt HLG LED. However this light gave me a perfect, frosted, picture perfect grow of 3 compact plants 2 grows ago.

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What you are seeing is normal. It is common for a cannabis plant to increase in size by 50% to 100% during the first few weeks in flowering. There’s not much you can do to manage it other than considering topping and supercropping.


Are you saying you grew 3 plants that buded with just a 100 watt light?
Do you have any pictures?

This was just before harvest of approximately 12 ounces dry. 3 plants.


There are many situations that can leave you with tall plants, but I feel one potentially stands out here. When growing multiple plants if they touch each other they will also compete with each other for light. This will cause plants to get taller than they would otherwise.


Grow dots are not the cause my freind.
As @Myfriendis410 said, if anything “caused” it, it would be low light intensity.
However, it’s most likely just genetics, it is extremely common for cannabis to streatch double in size :+1:


Thanks 1HappyPappy.

You’re the 2nd or 3rd person who have made this same comment about rapid stretch being normal.

If this is so common why are the majority of smaller grow tents limited to just 60 to 64 inches in height?

All grow tents should be 90 inches or more (to accommodate most 96 inch ceilings) to compensate for standard cannabis heights without “training” a plant into a pretzel.

I think the culprit is most likely too large a container for the root ball. You can see in the Dixie cup contests here what smaller containers will do to cannabis height.

Like I’ve said earlier, from now on I’ll use Dixie Cups to just sample different strains or 1/2 gallon and/or 1 gallon pots to limit the Jolly Green Giant (JGG) stretch conundrum.

12 ounces from a 100 watt light is amazing! That is over 3 grams per watt!!! Very impressive, indeed. :man_mage: I am pretty jazzed when I get over 1 gram per watt.


“ If this is so common why are the majority of smaller grow tents limited to just 60 to 64 inches in height?”…

1). People will buy them, thinking it’s enough, when more times than not it is too small…for weed. There are probably a few people who grow herbs, and what not that will fit though.

  1. some growers are skilled enough at shaping weed by scrog/topping andlight stress training to keep a very low profile on plant

I have I think six foot tall tents, and so far, all my plants (both auto and photo, have come out pretty short and shrub like.

Perhaps genetics, or something I do stunts them. In any case, I’m sure their marketing gurus have determined that it’s cost effective to make the shorter tents, and maybe even more lucrative as people buy small tent, find out it’s really too short, then buy another taller tent.

When that’s the case, you can always utilize short tent for baby plants or as a drying tent.

As to how you can limit stretch? Super cropping/ topping and training to grow outwards rather than upward

Or treat like total crap when young, stunt their growth, and hope for best… this method is not recommended lol


My apologies, I missed that you have two 100 watt lights.

Still, 1.5 grams per watt is still an amazing number that most of us would be thrilled to get.


I’m only using 2 HLG 100 LEDs because I’m lighting the tent sideways through the unzipped door for these 57 inch plants in a 60 inch tall tent. Huge unwanted PIA. The 2nd board is handling the bottom buds and the runt Autoflower being shaded.

Those 3 plants in the pictures above grew under one HLG 100 watt board using the Samsung LM301B LEDs. Spaced at 20 inches most of the time.

This fixture produces 220 PPF, 14,000+ Lumens with just 95 Watts of power. Equivalent to 220W T5 or 300W CFL output or 200W metal halide.


You will need the ppfd to be more than 600 - 700 to get decent buds. I run mine at 900 to 1000.


One light gave me 12 ounces from 3 plants in a 2x2x5 tent that all looked like this photo.


Very nice…Here is one of mine (not one of my best but the photo was handy).

The bud is a little over 3" across at the wide part. This was an auto-flower that only had eight or nine colas like this. Most of my photo-period plants grown in a SCROG have 20 or more tops like that. Most of the photo period plant colas are 10 inches or more in length.


Here are the freshly chopped colas from an ILGM Chocolupe that I grew a few grows ago.


I use the HLG 100s in my grows, and I get good results in my 2x6 closet growing 3 medium sized plants, actually 95w boards per plant, I average 4.2 ounces per plant of nice dense buds, 3/4 pound per grow, 3 grows a year, these boards can produce. Here’s my closet but I invite you all to check out my Simple grow


Hey @420Buddy do you still have a full tent? I would love to see pictures of that, sounds like a fantastic haul. I use my lights to control stretching and top, but I grow only photos so I can flip when I want to control size. Autos I didn’t have as much control.

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I haven’t taken any yet. Mainly because its not what I consider the ideal grow. I’ll take a couple for this thread tomorrow to document a couple out of control ILGM autoflower strains. An Afghan at 57+ inches, Sour Diesel at 55+ inches, Wedding Cake shaded at 15 inches

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