Amateur-Grower
Well-Known Member
Just wondering what a good intensity for autoflowers are. I had my light as high up as I could and got around 600 PAR, but noticed light stress or heat stress so I lowered my light intensity to about 25%
Autoflower Lignt Stress
- Thread starter Amateur-Grower
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Nice tent and nice light!
My grow is in a 2' x 4' tent and wish I had the room for a larger setup.
In terms of light intensity, I haven't see a marked difference between autos and photos. Both autos and photos will thrive in PPFD's >1000 but I have only run photos at >1100. I grow in hydro and measure light daily using an Apogee.
Some observations and questions about your grow - the hang height on those lights is very high. Those lights are at least 36" from the plants — is that a Diablo/Tomahawk? I ask because very few lights can generate a PPFD that high at that hang height.
What are you using to measure light levels?
Based on their size, I'd guess those plants are14 days old. Is that about right?
What setting is your fan on and have you changed the intensity of the fan recently?
In the bottom photo, with plants being numbered 1 to 4, back left, back right, etc. - plants 1 and 2 aren't easy to see but they appear to be smaller than 3 and 4 and they appear to have curled leaves. Plant 3 doesn't look to have curled leaves. Plant 4 is the plant in the first photo, is that correct?
While 600µmol for a 14 day old plant is very high for young plants, I've also seen grows that have been subject to wind burn. From the pictures, the plants closest to the light have curled leaves but plant #3, front left, doesn't appear to have curled leaves. Is that correct or am I off base with that?
I've posted the daily light readings for an auto grow I did in 2022. The numbers are pretty representative of PPFD or DLI values that I've used in the early parts of a grow. That light schedule is aggressive but, for three years now, I've given my plants a lot of light. I had a couple of instances of canoeing which let me know that I was above the light saturation point. With that, I backed off a bit for a few days and then continued to increase PPFD.
PPFD is a universally understood value. I'd go with that rather than dropping the dimmer to 25%.
My grow is in a 2' x 4' tent and wish I had the room for a larger setup.
In terms of light intensity, I haven't see a marked difference between autos and photos. Both autos and photos will thrive in PPFD's >1000 but I have only run photos at >1100. I grow in hydro and measure light daily using an Apogee.
Some observations and questions about your grow - the hang height on those lights is very high. Those lights are at least 36" from the plants — is that a Diablo/Tomahawk? I ask because very few lights can generate a PPFD that high at that hang height.
What are you using to measure light levels?
Based on their size, I'd guess those plants are14 days old. Is that about right?
What setting is your fan on and have you changed the intensity of the fan recently?
In the bottom photo, with plants being numbered 1 to 4, back left, back right, etc. - plants 1 and 2 aren't easy to see but they appear to be smaller than 3 and 4 and they appear to have curled leaves. Plant 3 doesn't look to have curled leaves. Plant 4 is the plant in the first photo, is that correct?
While 600µmol for a 14 day old plant is very high for young plants, I've also seen grows that have been subject to wind burn. From the pictures, the plants closest to the light have curled leaves but plant #3, front left, doesn't appear to have curled leaves. Is that correct or am I off base with that?
I've posted the daily light readings for an auto grow I did in 2022. The numbers are pretty representative of PPFD or DLI values that I've used in the early parts of a grow. That light schedule is aggressive but, for three years now, I've given my plants a lot of light. I had a couple of instances of canoeing which let me know that I was above the light saturation point. With that, I backed off a bit for a few days and then continued to increase PPFD.
PPFD is a universally understood value. I'd go with that rather than dropping the dimmer to 25%.
Amateur-Grower
Well-Known Member
This is what I use to check out the light intensity. My plants must've stunted cause they were at day 20 when I took that picture. It's also been really hot where I am at and the inside of my tent has been high 90's. I'll take more pictures later today. Thank you for the help!
coreywebster
Well-Known Member
Probably more heat stress if it's high 90s.
Leaf edges curl up and stomata close to slow transpiration down when it's really hot.
Leaf edges curl up and stomata close to slow transpiration down when it's really hot.
No idea if that's even a PAR meter. I suspect that it's one of the meters that uses a gallium arsenide sensor to keep price down.
90° temps - yeh, that's tough on cannabis but the other side of the equation is RH.
If you're not keeping RH at 80%±, that's a lot of stress on the plant. Add in the breeze from a fan and…who knows.
Those are contributing factors, though. The big driver will be 600µmol. Drop PPFD to 300µmol or so and then gradually increase.
What light is that BTW? Looks like you've got plenty of PPFD to spare!
Amateur-Grower
Well-Known Member
#4 - the last photo - is looking pretty good.
#3 - has curled leaf edges but that's not a light issue. When plants get too much light they roll the leaves inward, not just the very edges of the leaves. Are they, perhaps, still in the process of "de-canoeing" (new word).
#1 and #2 - are a different strain than 3 and 4 but, at this stage of their growth, almost look like a different plant species. Have you grown this strain before?
What's your PPFD?
Amateur-Grower
Well-Known Member
Blue_Focus
Well-Known Member
What's your light schedule? I grow autoflowers and currently have mine at 18/6.
Also I've found that autoflowers don't like the bright light like a photo period does.
My current autoflower growing under 450 PPFD.
Also I've found that autoflowers don't like the bright light like a photo period does.
My current autoflower growing under 450 PPFD.
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That's about right for a plant that size but the plant is the best judge of that, right?
What's going on with #1 and #2? What throws me is their branching. I haven't seen that in a cannabis plant.