Greetings, AFN members, OSP here. I’m a new AFN member moving in from another forum. After sneaking around a number of threads here looking for secret information, I’ve decided to start this thread. I want to evaluate the effects of light intensity on plant growth. More specifically, how lighting can be used to encourage or minimize plant stretch.
In the short time I’ve been a member here I’ve met a number of very knowledgeable growers, and I’m inviting each of you to participate or chime in as you see fit. Since I am new to AFN I’m sure I’ve missed a lot of interested parties. If you are reading this feel free to tag in anyone I’ve missed:
@fettled6 @912GreenSkell @bushmasterar15 @Waira @MedGrower @Son of Hobbes @Nosias @Screwauger @HemiSync @ChroToker @Need4Weed
I've grown photoperiods since forever under High Intensity Discharge (HID) lighting, and stretch has always been a thing to plan for. Several years ago I decided to experiment with an autoflower freebie, and since then I've completed (12) single-plant autoflower grows. To the point that I'm not doing photoperiods anymore. Maybe again one day. I have a Colombian Gold freebie that has brought back memories, but not today.
In the process of migrating from photoperiods to autoflowers, I also began a transition from HID to LED lighting. Over this period I began to see a pattern. With every one of my HID grows, all my autoflowers exhibited healthy stretch. It started quicker than photoperiods, but the overall effect was similar. Low Stress Training (LST) was effective, bud quality was very good and yield was very good to excellent. But with my LED grows, absolutely NONE of my autoflowers stretched. I had complete grows that never exceeded 10” in height.But with LED I can’t help but think much more is possible. Over 44+ years of growing I’ve seen well trained plants out-yield plants with no training every time. So I want the ability to encourage stretch in my plants.
For the sake of other AFN members, I believe the inverse of this stretch phenomena could be very beneficial to growers with a limited amount of grow space headroom. I want to prove or disprove, to some relative degree of certainty, that light intensity can be used to influence stretch when growing cannabis. But first I need to gather data on other growers’ experiences with plant stretch, and its association to light intensity during the plant’s lifecycle.
This is NOT an opinion piece of “is LED better than HID?” LED is certainly different, and in many respects (heat &efficiency) we all know it IS better. And this is NOT an attempt to compare LED lighting brands. There are numerous characteristics of LED lighting that determine light quality, and our most excellent site admin, @Son of Hobbes has started a thread on what parameters can be used to define those. His efforts may be reviewed here: https://www.autoflower.org/threads/what-should-be-on-a-grow-light-review.64857/ I’ve added a few well chosen thoughts on that topic - PAR watts, efficiency, most favored color spectrum, etc.. But I’m not smart enough to make that final differentiation so I’m happy to watch as SOH finishes that. The only facts I intend to present here are those I’ve experienced with my auto grows.
There are a number of other factors besides lighting that affect plant growth. In an effort to keep this thread focused on light intensity with no outside variables, I asked one of AFN’s most experienced members, MedGrower, for his input. His comments, and my follow up confirming those variables were addressed, can be found in his grow thread located at https://www.autoflower.org/threads/...-dwc-hs1-telos-0008.64718/page-2#post-1758834
In consideration to MedGrower, if you have any comments / questions, send them to me or post here. I don’t want to trash his grow thread with my conspiracy theory so I’m asking each of you to please share that consideration with me.
For the sake of this study I’d like to focus on the two main lighting factors that control intensity - light height throughout the grow cycle, and “power” of the light over the grow canopy; i.e. watts per sq.ft.. Light height is an easy factor to define as long as we document the variation during a plant’s growth cycle. Plant canopy area is an easy measure. Power consumption is an easy measure. I know, watts per sq.ft. is not the most meaningful measure of an LED’s efficiency. But until or if we ever reach consensus of an industry standard measure for all lighting types, I am using watts consumed at the wall, per square foot. No matter how much we insist this is not the best method (I agree), wattage consumed per square foot is the only readily available factor across all lighting types. And no matter how much we agree to disagree, it should provide a reasonable enough classification of small / medium / large lighting to support this study.
My light ratings are 62.5W/sq.ft. for HID and 65W.sq.ft. for LED. As to other influences on plant stretch, my grow techniques with HID and LED are as close to identical as one can get for environmental control and nutrient regimen. So enough intro, let’s kick this in the ass as I describe my experiences with autoflowers to date.
My starting system for HID is a 250W cooltube and batwing reflector with a metal halide bulb for veg and a high pressure sodium for bloom. The tent is a 4 sq. ft. system (2' X 2' X 5’3") by Secret Jardin. I configured it with (2) 4” 170CFM centrifugal fans, one for light cooling and the other for odor control through a 12” X 4” Phresh carbon filter). My nutrient regimen is General Hydroponics’ expert recirculating formula with some strength and slight ingredient tweaks. This regimen has not changed between HID and LED grows.
I grow hydroponically, and my system is configured for a single plant in a DIY 4 gallon Ebb ‘n Gro net pot with hydroton clay pebbles. The system floods automatically every two hours for 15 minutes. I call this DIY because I do not rely upon the complex valves and fittings normally associated with commercially available ebb and grow systems. Those systems rely upon multiple pumps, flow control valves and timers opening and closing with each flood cycle to deliver and recover nutrients to/from the plant. A strength of these commercial systems is they enable the reservoir to sit at the same height as the grow containers. Negatives are they are complex and expensive. My system relies upon a passive DIY manifold sitting on top of the reservoir, and the only moving part is an inexpensive and very reliable 170 gph hydro pump. Total ebb n’grow component cost with four net pot buckets was under $100. I bought four net pot buckets to simplify plant positioning changes throughout my grows, and to run parallel grows in separate tents. My DIY manifold does raise system height by the height of the reservoir, but the entire reservoir, tent and plant container system comes in under 7’ tall. It’s a quality system with all the right parts, and it fits in a closet if it has to (mine doesn’t).
I’m going to drift off topic for a moment as I’ve been known to do. I’ve used all types of hydro systems for many years and this is my favorite. It re-oxygenates the root zone after each flood every two hours. Supply to the net pot is positive pressure flow, while draining is passive / gravity, so aggressive root growth is pushed back into the net pot and will never cause a clog in the system’s hydro line. And even if a clog were to somehow mysteriously occur, overflow is not possible due to the design of the manifold. The system is fully automated - I recently took an eight day trip with no worries that the system would stay fully functional until I returned, and it did. A separate reservoir (I use 12 to 14 gallons) from the grow container makes nutrient changes and maintenance simple, and the added capacity gives me plenty of “headroom” in the nutrient mix as the plant drinks.
Here’s a pic of the original HID tent. The manifold is the white bucket to the left outside the tent. The ebb ‘n Gro bucket is slightly out of position on the shelf behind the tent:
In the short time I’ve been a member here I’ve met a number of very knowledgeable growers, and I’m inviting each of you to participate or chime in as you see fit. Since I am new to AFN I’m sure I’ve missed a lot of interested parties. If you are reading this feel free to tag in anyone I’ve missed:
@fettled6 @912GreenSkell @bushmasterar15 @Waira @MedGrower @Son of Hobbes @Nosias @Screwauger @HemiSync @ChroToker @Need4Weed
I've grown photoperiods since forever under High Intensity Discharge (HID) lighting, and stretch has always been a thing to plan for. Several years ago I decided to experiment with an autoflower freebie, and since then I've completed (12) single-plant autoflower grows. To the point that I'm not doing photoperiods anymore. Maybe again one day. I have a Colombian Gold freebie that has brought back memories, but not today.
In the process of migrating from photoperiods to autoflowers, I also began a transition from HID to LED lighting. Over this period I began to see a pattern. With every one of my HID grows, all my autoflowers exhibited healthy stretch. It started quicker than photoperiods, but the overall effect was similar. Low Stress Training (LST) was effective, bud quality was very good and yield was very good to excellent. But with my LED grows, absolutely NONE of my autoflowers stretched. I had complete grows that never exceeded 10” in height.But with LED I can’t help but think much more is possible. Over 44+ years of growing I’ve seen well trained plants out-yield plants with no training every time. So I want the ability to encourage stretch in my plants.
For the sake of other AFN members, I believe the inverse of this stretch phenomena could be very beneficial to growers with a limited amount of grow space headroom. I want to prove or disprove, to some relative degree of certainty, that light intensity can be used to influence stretch when growing cannabis. But first I need to gather data on other growers’ experiences with plant stretch, and its association to light intensity during the plant’s lifecycle.
This is NOT an opinion piece of “is LED better than HID?” LED is certainly different, and in many respects (heat &efficiency) we all know it IS better. And this is NOT an attempt to compare LED lighting brands. There are numerous characteristics of LED lighting that determine light quality, and our most excellent site admin, @Son of Hobbes has started a thread on what parameters can be used to define those. His efforts may be reviewed here: https://www.autoflower.org/threads/what-should-be-on-a-grow-light-review.64857/ I’ve added a few well chosen thoughts on that topic - PAR watts, efficiency, most favored color spectrum, etc.. But I’m not smart enough to make that final differentiation so I’m happy to watch as SOH finishes that. The only facts I intend to present here are those I’ve experienced with my auto grows.
There are a number of other factors besides lighting that affect plant growth. In an effort to keep this thread focused on light intensity with no outside variables, I asked one of AFN’s most experienced members, MedGrower, for his input. His comments, and my follow up confirming those variables were addressed, can be found in his grow thread located at https://www.autoflower.org/threads/...-dwc-hs1-telos-0008.64718/page-2#post-1758834
In consideration to MedGrower, if you have any comments / questions, send them to me or post here. I don’t want to trash his grow thread with my conspiracy theory so I’m asking each of you to please share that consideration with me.
For the sake of this study I’d like to focus on the two main lighting factors that control intensity - light height throughout the grow cycle, and “power” of the light over the grow canopy; i.e. watts per sq.ft.. Light height is an easy factor to define as long as we document the variation during a plant’s growth cycle. Plant canopy area is an easy measure. Power consumption is an easy measure. I know, watts per sq.ft. is not the most meaningful measure of an LED’s efficiency. But until or if we ever reach consensus of an industry standard measure for all lighting types, I am using watts consumed at the wall, per square foot. No matter how much we insist this is not the best method (I agree), wattage consumed per square foot is the only readily available factor across all lighting types. And no matter how much we agree to disagree, it should provide a reasonable enough classification of small / medium / large lighting to support this study.
My light ratings are 62.5W/sq.ft. for HID and 65W.sq.ft. for LED. As to other influences on plant stretch, my grow techniques with HID and LED are as close to identical as one can get for environmental control and nutrient regimen. So enough intro, let’s kick this in the ass as I describe my experiences with autoflowers to date.
My starting system for HID is a 250W cooltube and batwing reflector with a metal halide bulb for veg and a high pressure sodium for bloom. The tent is a 4 sq. ft. system (2' X 2' X 5’3") by Secret Jardin. I configured it with (2) 4” 170CFM centrifugal fans, one for light cooling and the other for odor control through a 12” X 4” Phresh carbon filter). My nutrient regimen is General Hydroponics’ expert recirculating formula with some strength and slight ingredient tweaks. This regimen has not changed between HID and LED grows.
I grow hydroponically, and my system is configured for a single plant in a DIY 4 gallon Ebb ‘n Gro net pot with hydroton clay pebbles. The system floods automatically every two hours for 15 minutes. I call this DIY because I do not rely upon the complex valves and fittings normally associated with commercially available ebb and grow systems. Those systems rely upon multiple pumps, flow control valves and timers opening and closing with each flood cycle to deliver and recover nutrients to/from the plant. A strength of these commercial systems is they enable the reservoir to sit at the same height as the grow containers. Negatives are they are complex and expensive. My system relies upon a passive DIY manifold sitting on top of the reservoir, and the only moving part is an inexpensive and very reliable 170 gph hydro pump. Total ebb n’grow component cost with four net pot buckets was under $100. I bought four net pot buckets to simplify plant positioning changes throughout my grows, and to run parallel grows in separate tents. My DIY manifold does raise system height by the height of the reservoir, but the entire reservoir, tent and plant container system comes in under 7’ tall. It’s a quality system with all the right parts, and it fits in a closet if it has to (mine doesn’t).
I’m going to drift off topic for a moment as I’ve been known to do. I’ve used all types of hydro systems for many years and this is my favorite. It re-oxygenates the root zone after each flood every two hours. Supply to the net pot is positive pressure flow, while draining is passive / gravity, so aggressive root growth is pushed back into the net pot and will never cause a clog in the system’s hydro line. And even if a clog were to somehow mysteriously occur, overflow is not possible due to the design of the manifold. The system is fully automated - I recently took an eight day trip with no worries that the system would stay fully functional until I returned, and it did. A separate reservoir (I use 12 to 14 gallons) from the grow container makes nutrient changes and maintenance simple, and the added capacity gives me plenty of “headroom” in the nutrient mix as the plant drinks.
Here’s a pic of the original HID tent. The manifold is the white bucket to the left outside the tent. The ebb ‘n Gro bucket is slightly out of position on the shelf behind the tent:
). 
