Lighting What's the best lighting cycle for autos - 24/0, 20/4 or 18/6

[pop22]

DLI is based on how much light a plant needs in one day. It's been a while since I read on this, but I think what happens is photosynthesis slows down so that the plant can run other necessary processes and use some of the sugars created. Think of it like, once the wharehouse is full, now what? You stop production until some of the product is used.

And I had a 1963 chevy Impala convertable with a 3 speed with overdrive...lol!

@pop22 Well, maybe it is just an old wives' tale, and i don't even know if i can find the info, it's been a while. But, i will look. Anyway, the subject of those discussions was about plants that...i dunno the correct term...but there is no stretch and all the leaves/buds want to grow at one spot, sort of choking. Supposedly, to get them out of that, was to lower temps in the dark time...not much, not too cold. I took it as a known thing, and it was years ago, probably under different lights than we have, currently.

Thanks for the phone app. info. I had no idea.

So, are you saying that with autos, that after 18 hours,and given more light, that the slowed photosynthesis is some sort of waste, or bad thing? I don't know how to process that info. Does it mean something like, when i'm saturated with vitamin D, i don't need the sun anymore? Or is it more like 'overdrive' on a vehicle (if you are old enough to remember that) and things can just coast happily along, with less power?

 

[Luigi]

Funny how many guys say 1212 is not proper af light cycle. Just came here to throw my 2c that I've seen autos grow beside photos and produce good yield + quality. 250-300g from one gorilla cookies plant under hps.

Now experimenting with 20-4, and plants seem droopy last hours, dont like how they look. Lowering dli did nothing, and even one bush that gets probably 50% of the light of other plants shows same drooping. So moving to 18-6 for now

Do you guys think this end of ligth cycle droop is affected by the amount of light, or total hours of light?

 

[pop22]

I've grown autos under 12/12 also. Doesn't mean they'll grow to their full potential. We need a better idea of what the DLI for autos should be.
I believe the droop is an indication of the plant being maxed out on photons, baring other factors that cause droop.. I'm finding that with modern LED lighting, if you keep your plants in the 700 - 900 PPFD range, and don't use CO2 enhancement, 18/6 is about where they max out.

 

[Luigi]

I had ~640ppfd with 20-4 cycle, thats around 46DLI, lowered to 550ppfd 40DLI and noticed no difference. Maybe thats still too much, its a possibility. 5 Weeks behind, on week6. It just seemed weird that one smaller plant is drooping just as much in shadow.
Also using new generation full spectrum leds.

 

[TrichomeAssassin]

Depends on the light. Old blurples I ran 24/7. Quantum boards & Autocob types 20/4.

 

[Delps8]

Funny how many guys say 1212 is not proper af light cycle. Just came here to throw my 2c that I've seen autos grow beside photos and produce good yield + quality. 250-300g from one gorilla cookies plant under hps.

Now experimenting with 20-4, and plants seem droopy last hours, dont like how they look. Lowering dli did nothing, and even one bush that gets probably 50% of the light of other plants shows same drooping. So moving to 18-6 for now

Do you guys think this end of ligth cycle droop is affected by the amount of light, or total hours of light?

Bugbee was asked about this he said that the best working theory is that plants sense that it's sunset.

Multiple researches have stated that cannabis will run very happily with a 24 hours photoperiod and will thrive at up to the light saturation point which is a PPFD of 800-1000µmols.

 

[Delps8]

I've grown autos under 12/12 also. Doesn't mean they'll grow to their full potential. We need a better idea of what the DLI for autos should be.
I believe the droop is an indication of the plant being maxed out on photons, baring other factors that cause droop.. I'm finding that with modern LED lighting, if you keep your plants in the 700 - 900 PPFD range, and don't use CO2 enhancement, 18/6 is about where they max out.

Cannabis has a light saturation point of 800-1000µmols and will grow with a photoperiod of 24/0. I've been interested in this aspect of growing and, like a lot of growers, kept my plants at DLI's in the 40's. They seem to do just fine and, of course, they do.

Researchers have shown that there is a direct, linear relationship between DLI and plant yield, crop yield, and crop quality - the more light you give cannabis, the bigger the yield, the better the yield, and the more flower/leaf you get. I read the research when I started growing, going on two years ago now, but, like a lot of growers kept my DLI's in the 40's. That's just because…

Autos are part of the cannabis species so they will thrive on up to about 1k µmols (non-CO2). Even though I knew the research data, I didn't get my last grow out of the 40's until about ⅔ of the way through the grow. I upped PPFD into the 900's and keep it there until a few weeks before the end of the grow. The only reason I turned down the lights is that the plants were so "full" of colas that there was no sense in keeping the light turned up (I use a Growcraft X3 full cycle light for flower). At 800 and 900+ µmols, there was no indication of light stress. Yield was significant at ≈ 750 grams/square meter (2' x 4' tent yielded 724 grams

The light schedule is here:

I started a grow of two Strawberry Pie autos and they're in day 41. One of the seedlings, Alice, had very damaged leaves and is significantly smaller than the other, Annie. They were germinated indoors due to a heat wave here in Southern California. During that time, they were lit by a Vipar Spectra XS-1500 + a Rapid LED Royal Blue puck.

On day nine, they were moved into the tent (in the garage) and a Growcraft X2 veg light was used. The XS-1500 was suspended between the light rails of the X2 and was positioned over Annie to provide additional light.

On day 38, the X2 veg light was replaced by a Growcraft X3 full cycle/flower light. The left side of the X3 has been lowered by 1" to provide a uniform light cast. The lighting levels are as shown here:

Re light levels for autos - the light saturation point for cannabis is 800-1000µmols. Autos are a hybrid version of a plant in the cannabis species. Ruderalis genes control the flowering process in autos but there's no indication that alters the fact that it's a plant in the species Cannabis which is a "high light" C3 plant.

What's the "DLI for autos"? I have seen nothing to indicate that it's any different than for the other strains of cannabis.

growlightmeter.com publishes a chart showing recommended DLI. I traded email with the programmer when I tested Korona and then when I tested Photone (note - I chose to not use Korona/Photone, choosing to use an Apogee, instead.) When I contacted him in April about my tests of Photone, I asked him about recommendations for DLI for autos since, at that time, he didn't a chart for autos. His response was to use 45 mols. When I asked about citations for the recommendations, he referred me to the citations on the site. You'll note that there are none.

In contrast, if you read "the research" as well as look at manufacturer's web sites, you'll see that they use the 1000 value that's the high side of the light saturation point.

As Bugbee states in one of his YouTube videos, if you're going to "push" your plants (his description) the other factors in the grow environment need to be optimal.

Re. measuring PPFD - I chose not to use Photone because it was highly inaccurate on my iPhone XS Max. As a programmer for the past 30+ years, I have some idea of the hoops challenges faced in creating and supporting Photone and, while I applaud his efforts, there's a simple, easy to use, inexpensive alternative (that doesn't require the kludge of putting a strip of paper over the sensor). Get a Uni-T light meter and use the conversion factor.

I've tested the Vipar Spectra XS-1500 and the Growcraft X2 against a Uni-T light meter and the conversion factor of 0.015 is more than sufficiently accurate.

Long posting - in short, autos are cannabis plants. Get your grow squared away, get a light meter, and turn it up to 11 as soon as you can. Research shows that the more light you give your plants, you get more, higher quality weed.

 

[pop22]

I've read much of this also. However, there is NO data regarding autof;owers and all you've said in regards to them is merely an assumption. You may be right but you have nothing to support it. Ruderalis is a strange plant and there's more to it than just it's autoflowering gene. And even with photoperiods, When the plants reach their maximum DLI they have have mechanisms such as light avoidance to reduce photosynthesis so that other processes can take precedence.

Let's consider Equatorial Sativas. They are much lighter green color, because the have fewer chloroplasts. Why? Because even though they have a short day, equatorial plant get the most light of any plants on earth. They have evolved and adapted to their environment to take maximum advantage of it. The same is true of most Indicas, they have adapted to take advantage of the environment they are found in, which have longer days but lower light level. The same for Ruderalis. Each environment is very different. Blending these genetics has to have an effect on their biological processes. So saying that DLI requirements for autoflower hybrids will be the same as for photoperiods is likely inaccurate and we don't have research available to support these assumptions.

Wish I had the link, anyway, I read some time back that current research is suggesting that plants do need a rest period for optimal functioning. It was a preliminary study so we need to see further study as there is no guidance as to what may or may not be the optimal dark period, although with what we know about DLI and cannabis suggests that time to achieving maximum DLI will likely be a factor.

Cannabis has a light saturation point of 800-1000µmols and will grow with a photoperiod of 24/0. I've been interested in this aspect of growing and, like a lot of growers, kept my plants at DLI's in the 40's. They seem to do just fine and, of course, they do.

Researchers have shown that there is a direct, linear relationship between DLI and plant yield, crop yield, and crop quality - the more light you give cannabis, the bigger the yield, the better the yield, and the more flower/leaf you get. I read the research when I started growing, going on two years ago now, but, like a lot of growers kept my DLI's in the 40's. That's just because…

Autos are part of the cannabis species so they will thrive on up to about 1k µmols (non-CO2). Even though I knew the research data, I didn't get my last grow out of the 40's until about ⅔ of the way through the grow. I upped PPFD into the 900's and keep it there until a few weeks before the end of the grow. The only reason I turned down the lights is that the plants were so "full" of colas that there was no sense in keeping the light turned up (I use a Growcraft X3 full cycle light for flower). At 800 and 900+ µmols, there was no indication of light stress. Yield was significant at ≈ 750 grams/square meter (2' x 4' tent yielded 724 grams

The light schedule is here:

View attachment 1526890

I started a grow of two Strawberry Pie autos and they're in day 41. One of the seedlings, Alice, had very damaged leaves and is significantly smaller than the other, Annie. They were germinated indoors due to a heat wave here in Southern California. During that time, they were lit by a Vipar Spectra XS-1500 + a Rapid LED Royal Blue puck.

On day nine, they were moved into the tent (in the garage) and a Growcraft X2 veg light was used. The XS-1500 was suspended between the light rails of the X2 and was positioned over Annie to provide additional light.

On day 38, the X2 veg light was replaced by a Growcraft X3 full cycle/flower light. The left side of the X3 has been lowered by 1" to provide a uniform light cast. The lighting levels are as shown here:
View attachment 1526891

Re light levels for autos - the light saturation point for cannabis is 800-1000µmols. Autos are a hybrid version of a plant in the cannabis species. Ruderalis genes control the flowering process in autos but there's no indication that alters the fact that it's a plant in the species Cannabis which is a "high light" C3 plant.

What's the "DLI for autos"? I have seen nothing to indicate that it's any different than for the other strains of cannabis.

growlightmeter.com publishes a chart showing recommended DLI. I traded email with the programmer when I tested Korona and then when I tested Photone (note - I chose to not use Korona/Photone, choosing to use an Apogee, instead.) When I contacted him in April about my tests of Photone, I asked him about recommendations for DLI for autos since, at that time, he didn't a chart for autos. His response was to use 45 mols. When I asked about citations for the recommendations, he referred me to the citations on the site. You'll note that there are none.

In contrast, if you read "the research" as well as look at manufacturer's web sites, you'll see that they use the 1000 value that's the high side of the light saturation point.

As Bugbee states in one of his YouTube videos, if you're going to "push" your plants (his description) the other factors in the grow environment need to be optimal.

Re. measuring PPFD - I chose not to use Photone because it was highly inaccurate on my iPhone XS Max. As a programmer for the past 30+ years, I have some idea of the hoops challenges faced in creating and supporting Photone and, while I applaud his efforts, there's a simple, easy to use, inexpensive alternative (that doesn't require the kludge of putting a strip of paper over the sensor). Get a Uni-T light meter and use the conversion factor.

I've tested the Vipar Spectra XS-1500 and the Growcraft X2 against a Uni-T light meter and the conversion factor of 0.015 is more than sufficiently accurate.

Long posting - in short, autos are cannabis plants. Get your grow squared away, get a light meter, and turn it up to 11 as soon as you can. Research shows that the more light you give your plants, you get more, higher quality weed.

 

[WildBill]

I've read much of this also. However, there is NO data regarding autof;owers and all you've said in regards to them is merely an assumption. You may be right but you have nothing to support it. Ruderalis is a strange plant and there's more to it than just it's autoflowering gene. And even with photoperiods, When the plants reach their maximum DLI they have have mechanisms such as light avoidance to reduce photosynthesis so that other processes can take precedence.

Let's consider Equatorial Sativas. They are much lighter green color, because the have fewer chloroplasts. Why? Because even though they have a short day, equatorial plant get the most light of any plants on earth. They have evolved and adapted to their environment to take maximum advantage of it. The same is true of most Indicas, they have adapted to take advantage of the environment they are found in, which have longer days but lower light level. The same for Ruderalis. Each environment is very different. Blending these genetics has to have an effect on their biological processes. So saying that DLI requirements for autoflower hybrids will be the same as for photoperiods is likely inaccurate and we don't have research available to support these assumptions.

Wish I had the link, anyway, I read some time back that current research is suggesting that plants do need a rest period for optimal functioning. It was a preliminary study so we need to see further study as there is no guidance as to what may or may not be the optimal dark period, although with what we know about DLI and cannabis suggests that time to achieving maximum DLI will likely be a factor.

I read something simular.

One of my girls in the 4x4 looked droopy when I went to shape up one of her tentmates. I had made the mental note earlier that she was looking very perky and had that look like she was finally ready to 'get her EB on'.
After a few min, working on the plant, the light went out in the tent. I guess she hit her DLI.

 

[WildBill]

This is on 18/6 with the highest ppfd is around 525

Here's Fugue State at mid cycle today.

Here she is just about an hour until lights off just a few min ago. She's begun her droop and it's sleepy time.

Edit...............3BOG is even more dramatic.