PPFD and DLI Questions

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Fladawg01

Member
I understand these terms and know what they mean. I have a PPFD, DLI and Lux meter. and use it constantly to see what my plants are receiving.
For Seeding I don't use my main light, until after the 1st week. Then I will be at 50%. Honestly never checked it at that point. Light was set around 24 to 26 inches above plants.
For Vegetative growth, I had the light set at 60% for the first couple weeks then to 70%. My readings were 725 to 800 PPFD DLI was around 50 or more. No issue with plants. Light set at 22 inches above plant canopy.
Flowering: I am reaching anywhere from 890 on low end areas, but average 925 to 1000 PPFD amd 55 to 64 DLI. My girls are thriving. Light set at 18" above canopy.

There is a Professor on You Tube who teaches cannabis growing and does a very good tutorial on PPFD, DLI and Lux and the effects on cannabis grow. Accordingly he states the higher you can get the better for cannabis growth. But he does caution anything above 1000 that CO2 should be involved somehow. I am not going to use CO2 in my home, just an FYI.

What is the average for PPFD and DLI for these 3 stages most experienced growers are using? And heights of lights?
 
FmSwayze

FmSwayze

Well-Known Member
I'm ending my 2nd week of flower. Lights at 50% averages 42k lux across the canopy, like 700 PPFD approximately 30 DLI. End of day, they are ready to rest. If/when they dont look like they been worked hard I'll bump up the lights.

I read the plants. Perhaps our instruments are different, but I just ran a 53 DLI a few weeks ago and it was apocalyptic.

2x4 gorilla grow tent
2 HLG 260 kits
Lux meter is a UNI-T
Dr Earth dry amendments in soil mix
 
F

Fladawg01

Member
FmSwayze said:
I'm ending my 2nd week of flower. Lights at 50% averages 42k lux across the canopy, like 700 PPFD approximately 30 DLI. End of day, they are ready to rest. If/when they dont look like they been worked hard I'll bump up the lights.

I read the plants. Perhaps our instruments are different, but I just ran a 53 DLI a few weeks ago and it was apocalyptic.

2x4 gorilla grow tent
2 HLG 260 kits
Lux meter is a UNI-T
Dr Earth dry amendments in soil mix
Click to expand...
Interesting. As mine are thriving at the levels I stated. Growing Autos running a 20/4 schedule as well.
 
D

Delps8

Well-Known Member
Fladawg01 said:
I understand these terms and know what they mean. I have a PPFD, DLI and Lux meter. and use it constantly to see what my plants are receiving.
For Seeding I don't use my main light, until after the 1st week. Then I will be at 50%. Honestly never checked it at that point. Light was set around 24 to 26 inches above plants.
For Vegetative growth, I had the light set at 60% for the first couple weeks then to 70%. My readings were 725 to 800 PPFD DLI was around 50 or more. No issue with plants. Light set at 22 inches above plant canopy.
Flowering: I am reaching anywhere from 890 on low end areas, but average 925 to 1000 PPFD amd 55 to 64 DLI. My girls are thriving. Light set at 18" above canopy.

There is a Professor on You Tube who teaches cannabis growing and does a very good tutorial on PPFD, DLI and Lux and the effects on cannabis grow. Accordingly he states the higher you can get the better for cannabis growth. But he does caution anything above 1000 that CO2 should be involved somehow. I am not going to use CO2 in my home, just an FYI.

What is the average for PPFD and DLI for these 3 stages most experienced growers are using? And heights of lights?
Click to expand...
You're probably referring to Dr Bruce Bugbee.

Bugbee is the head of crop physiology a the University of Utah and, arguably, one of, if not the, leading researcher on cannabis. Over the past three years, I've studied all of the research of his that I can find as well as research from other sources. Despite the volume of research, there are a handful of key points that, fortunately, can be gleaned from a video released by a student of his (more on that, below).

The only sources that provide PPFD ranges are cannabis sites. There's value in that approach because it's helpful for guiding growers.

The rough guidelines:

Seedling 100-300
Vegetative 300-600
Flower 600-900

Companies that sell grow lights generally recommend hang heights + dimmer settings for their lights. Off the top of my head, I can't think of a vendor that recommends PPFD.

I can write a tome on this topic but I'll spare you. :-)

Bugbee recommends <1kµmol in ambient CO2 because that a very good guideline for most grows. My approach to growing is based on at least hundreds of hours of reading research/viewing and making notes to You Tube videos from Bugbee and others but one fairly recent video by a Bugbee student summarizes a vast amount of research.

The student is Mitch Westmoreland who is a PhD candidate under Dr. Bugbee. He released two videos early this year that summarizes the work that he's done for his thesis.

The two videos are below.



You'll note that there's no concept of setting light PPFD to certain general levels at different stages of their growth. I suspect that the rationale for that is because there's no particular reason to do so—research repeatedly and unequivocally indicates that crop yield and crop quality increase as light levels increase so there's particular no reason to not give your plants as much light as they can tolerate.
 
F

Fladawg01

Member
Delps8 said:
You're probably referring to Dr Bruce Bugbee.

Bugbee is the head of crop physiology a the University of Utah and, arguably, one of, if not the, leading researcher on cannabis. Over the past three years, I've studied all of the research of his that I can find as well as research from other sources. Despite the volume of research, there are a handful of key points that, fortunately, can be gleaned from a video released by a student of his (more on that, below).

The only sources that provide PPFD ranges are cannabis sites. There's value in that approach because it's helpful for guiding growers.

The rough guidelines:

Seedling 100-300
Vegetative 300-600
Flower 600-900

Companies that sell grow lights generally recommend hang heights + dimmer settings for their lights. Off the top of my head, I can't think of a vendor that recommends PPFD.

I can write a tome on this topic but I'll spare you. :-)

Bugbee recommends <1kµmol in ambient CO2 because that a very good guideline for most grows. My approach to growing is based on at least hundreds of hours of reading research/viewing and making notes to You Tube videos from Bugbee and others but one fairly recent video by a Bugbee student summarizes a vast amount of research.

The student is Mitch Westmoreland who is a PhD candidate under Dr. Bugbee. He released two videos early this year that summarizes the work that he's done for his thesis.

The two videos are below.



You'll note that there's no concept of setting light PPFD to certain general levels at different stages of their growth. I suspect that the rationale for that is because there's no particular reason to do so—research repeatedly and unequivocally indicates that crop yield and crop quality increase as light levels increase so there's particular no reason to not give your plants as much light as they can tolerate.
Click to expand...
Delps 8, Thanks for the share on the videos. Interesting stuff and yes it was Bugbee I was referring to. I would agree that if you can put the light on them and they thrive, keep it going. I look for any signs of stress on my girls but have only seen growth and great looking changes. My Wedding cake right now is a short stout plant in 2nd week of flower, currently putting on a silverish gray shine to her matching the white flowers she shows, she is my youngest yet surpassed my Mac1 who is 2 weeks ahead of her, but she caught up. I actually write in my little book I keep every days project, water, looks, feed etc. I am amazed at all the resilience and changes daily these plants. make. Sorry to dribble, thanks though again.
 
F

Fladawg01

Member
FmSwayze said:
Do you have pictures of your current grow?
Click to expand...
This was last week 2 of the girls, a Mac-1 Auto and Wedding Cake Auto. For some reason everything looks really yellowish and I need to find out whats with my phone camera. The EWedding Cake nearest pot is now taking on a silverish gray to her near the buds, makes her look like shes' wearing a fur coat to match the white flowers, really cool looking.
 

Attachments

FmSwayze

FmSwayze

Well-Known Member
Fladawg01 said:
This was last week 2 of the girls, a Mac-1 Auto and Wedding Cake Auto. For some reason everything looks really yellowish and I need to find out whats with my phone camera. The EWedding Cake nearest pot is now taking on a silverish gray to her near the buds, makes her look like shes' wearing a fur coat to match the white flowers, really cool looking.
Click to expand...
Good work man!
 
DanKiller

DanKiller

Well-Known Member
In light, more is always better, no matter at what stage, plants grow outside in any stage under low light and high intensity light with no problems
The difference is the rate of growth, weed can handle pretty much all the light you can throw at it if the conditions are dialed that is.

For CO2 you need to reach at least 1800 ppfd to have a noticable difference
Under that CO2 is just not necessary.
The sun push around 2000 ppfd on a high intensity tropical region day
You can't come near those values indoor evenly without burning everything from heat.
Screenshot_2024-09-21-12-54-45-805_com.miui.gallery.jpg

I usually start with a 250 hps for seedlings, when they get a lil bigger I blast them with the 600 hps to get monster leaves and roots
Screenshot_2024-09-21-12-55-57-271_com.miui.gallery.jpg
IMG_20240717_211536.jpg
More light, bigger and faster growth, not necessarily more growth...
New light science is bogus, 600-900 ppfd in flower ? Huh.. sounds like a joke.
The science behind light qtys is very old and verified, if someone is telling you to flower under 600 ppfd hes setting you up to fail
So many low intensity grows all around, look so horrible because all of those new teachings, weed has never been so lame across the board in the world right now because of that.
 
D

Delps8

Well-Known Member
Fladawg01 said:
Delps 8, Thanks for the share on the videos. Interesting stuff and yes it was Bugbee I was referring to. I would agree that if you can put the light on them and they thrive, keep it going. I look for any signs of stress on my girls but have only seen growth and great looking changes. My Wedding cake right now is a short stout plant in 2nd week of flower, currently putting on a silverish gray shine to her matching the white flowers she shows, she is my youngest yet surpassed my Mac1 who is 2 weeks ahead of her, but she caught up. I actually write in my little book I keep every days project, water, looks, feed etc. I am amazed at all the resilience and changes daily these plants. make. Sorry to dribble, thanks though again.
Click to expand...
You're welcome and I'm glad you found the vids useful.

"I look for any signs of stress on my girls but have only seen growth and great looking changes." - that's the ticket. As long as you're attentive, you're good to go. After about the second week in flower, you should be at max PPFD. The trick at that point is to get the temperature at the flower tops down.


" I actually write in my little book I keep every days project, water, looks, feed etc. I am amazed at all the resilience and changes daily these plants. make"
Excellent, yes. Keep a journal. I use Excel.

Columns-Day Date, Time, Comment, Level, Used, PPM, pH, PPFD, DLI


Grabbed this text from a grow last year. Part grow journal, part therapy, it looks like. ;-)

This was from day 78 which is week 11, day 1 and day 14 of flower.

125 is the water level, 0.6 gallons was used since the last reading for a total of 7.7 gallons taken up out of this res.
PPM is 570 (500 sales) and pH is 5.9

The info in the last three columns is PPFD data where I took 12 samples, in a grid pattern starting in the back left. That was a very level canopy.
1726926122297.png

By logging "more info than I'll ever need", I've got a history of how the grow was doing at a certain time. That's good in case something goes wrong but it's also helpful because it tells me what I need to do for my next grow. I don't have to try to remember "everything" because I've got a lot of the details in my previous grow journals. Good example - I'm starting now and I don't have to think about EC (PPM) or PPFD or how I set up whatever in the tent because I've got the details in my grow journals.

"Sorry to dribble, thanks though again."
No apologies necessary. Adding detail in a message thread can add a lot of value to the message thread. :-)
 

Attachments

F

Fladawg01

Member
Delps8 said:
You're welcome and I'm glad you found the vids useful.

"I look for any signs of stress on my girls but have only seen growth and great looking changes." - that's the ticket. As long as you're attentive, you're good to go. After about the second week in flower, you should be at max PPFD. The trick at that point is to get the temperature at the flower tops down.


" I actually write in my little book I keep every days project, water, looks, feed etc. I am amazed at all the resilience and changes daily these plants. make"
Excellent, yes. Keep a journal. I use Excel.

Columns-Day Date, Time, Comment, Level, Used, PPM, pH, PPFD, DLI


Grabbed this text from a grow last year. Part grow journal, part therapy, it looks like. ;-)

This was from day 78 which is week 11, day 1 and day 14 of flower.

125 is the water level, 0.6 gallons was used since the last reading for a total of 7.7 gallons taken up out of this res.
PPM is 570 (500 sales) and pH is 5.9

The info in the last three columns is PPFD data where I took 12 samples, in a grid pattern starting in the back left. That was a very level canopy.
View attachment 5427166

By logging "more info than I'll ever need", I've got a history of how the grow was doing at a certain time. That's good in case something goes wrong but it's also helpful because it tells me what I need to do for my next grow. I don't have to try to remember "everything" because I've got a lot of the details in my previous grow journals. Good example - I'm starting now and I don't have to think about EC (PPM) or PPFD or how I set up whatever in the tent because I've got the details in my grow journals.

"Sorry to dribble, thanks though again."
No apologies necessary. Adding detail in a message thread can add a lot of value to the message thread. :-)
Click to expand...
Yeah, nice information there. I don't keep nearly as much information as you have there. I mainly report what I see that day, how much liquid/food vs water, temps and RH once in awhile and growth. Maybe a comment or two on my feelings as well, like amazed or surprised or even the color changes I pick up on. Hopefully it will help next go round, but I also look and think every strain I try will be anew start. Most will be similar, but there are strains that will have different reactions to similar conditions. I just want to keep learning about the differences and hope I get it right, most of the time!
 
1

1212ham

Well-Known Member
Fladawg01 said:
I understand these terms and know what they mean. I have a PPFD, DLI and Lux meter. and use it constantly to see what my plants are receiving.
For Seeding I don't use my main light, until after the 1st week. Then I will be at 50%. Honestly never checked it at that point. Light was set around 24 to 26 inches above plants.
For Vegetative growth, I had the light set at 60% for the first couple weeks then to 70%. My readings were 725 to 800 PPFD DLI was around 50 or more. No issue with plants. Light set at 22 inches above plant canopy.
Flowering: I am reaching anywhere from 890 on low end areas, but average 925 to 1000 PPFD amd 55 to 64 DLI. My girls are thriving. Light set at 18" above canopy.

There is a Professor on You Tube who teaches cannabis growing and does a very good tutorial on PPFD, DLI and Lux and the effects on cannabis grow. Accordingly he states the higher you can get the better for cannabis growth. But he does caution anything above 1000 that CO2 should be involved somehow. I am not going to use CO2 in my home, just an FYI.

What is the average for PPFD and DLI for these 3 stages most experienced growers are using? And heights of lights?
Click to expand...
What meter are you using?
BTW, I think you need a certain number of posts before you can leave feedback?
 
F

Fladawg01

Member
1212ham said:
What meter are you using?
BTW, I think you need a certain number of posts before you can leave feedback?
Click to expand...
I have a pretty decent phone app and have had a Lux Meter for quite a few years now.. I compared the against each other for Lux and they were real close to each other. So I trust the phone app now.
 
D

Delps8

Well-Known Member
Fladawg01 said:
Yeah, nice information there. I don't keep nearly as much information as you have there. I mainly report what I see that day, how much liquid/food vs water, temps and RH once in awhile and growth. Maybe a comment or two on my feelings as well, like amazed or surprised or even the color changes I pick up on. Hopefully it will help next go round, but I also look and think every strain I try will be anew start. Most will be similar, but there are strains that will have different reactions to similar conditions. I just want to keep learning about the differences and hope I get it right, most of the time!
Click to expand...
That's all helpful info. It will come in handy in future grows.
 
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