Flower light question.

Blue_Focus · Mar 25, 2024

I checked outside today around noon and why do they only recommend 1,000 to flower at? Why not higher?

I used the Photone App. I'll check it another day with my PPFD meter.

Moflow · Mar 25, 2024

Im at 55°N.
Here's what I get on the 21st June, around midday.
Unfortunately sunshine is a rarity in these parts.

It drops quite considerably when there is cloud cover though
Early July

II'm running 1800 over some indoor plants at the moment just to see what'll happen.
Nine days since I measured 1800 ont par meter.
Nothing detrimental so far......

I normally use around 1000 for flowering myself.

hillbill · Mar 25, 2024

If I get too much over 1000ppfd, plants stress and show signs of LED light burn.

Tolerance Break · Mar 25, 2024

It's no different than indoors.

The plant needs co2 for photosynthesis. Indoors, they are often limited by the air in the lung room and the fans exchanging air. Running co2 is inefficient without a sealed set up, but you can push them much harder.

Outdoors, there is ample co2 in a sealed environment, it just so happens that it's earth's atmosphere, so they can get pushed harder. Spectrum might play a roll too, but I'm providing the most layman explanation I can because I'm not a scientist.

Delps8 · Mar 25, 2024

Blue_Focus said:
I checked outside today around noon and why do they only recommend 1,000 to flower at? Why not higher?

PPFD at noon can hit 2300±µmol but that's only for a limited number of days, at certain latitudes, if the weather is good. Over the course of a growing season, PPFD/DLI is much lower.

Why the 1k level? That's pretty much the max sustained level that cannabis can tolerate in ambient CO2. The attached paper shows that researchers were able to grow at 1800µmol. Try as I might, I haven't been able to get my grows to handle more than 1050-1100µmol and I've put a fair amount of time and money into optimizing a grow environment.

Blue_Focus said:
I used the Photone App. I'll check it another day with my PPFD meter.

I'd be interested in your results.

Delps8 · Mar 25, 2024

Tolerance Break said:
It's no different than indoors.

The plant needs co2 for photosynthesis. Indoors, they are often limited by the air in the lung room and the fans exchanging air. Running co2 is inefficient without a sealed set up, but you can push them much harder.

Outdoors, there is ample co2 in a sealed environment, it just so happens that it's earth's atmosphere, so they can get pushed harder. Spectrum might play a roll too, but I'm providing the most layman explanation I can because I'm not a scientist.

Amen to the CO2. Per Bugbee, you get a boost in yield without even increasing the PPFD. The number that I've seen if you bump CO2 and light is 25% to 30% increase in yield.

Blue_Focus · Mar 26, 2024

Tolerance Break said:
It's no different than indoors.

The plant needs co2 for photosynthesis. Indoors, they are often limited by the air in the lung room and the fans exchanging air. Running co2 is inefficient without a sealed set up, but you can push them much harder.

Outdoors, there is ample co2 in a sealed environment, it just so happens that it's earth's atmosphere, so they can get pushed harder. Spectrum might play a roll too, but I'm providing the most layman explanation I can because I'm not a scientist.

So if I pipe the air in from outside, I'll be good to go?

Tolerance Break · Mar 26, 2024

Blue_Focus said:
So if I pipe the air in from outside, I'll be good to go?

I don't think its quite that simple, but in theory perhaps. Keeping a constant negative pressure while bringing in enough air to keep the plants happy seems like the biggest hurdle, that and keeping the smell concealed while keeping the bugs outside.

Tolerance Break · Mar 26, 2024

Also worth considering, you're talking about the environment plants have evolved in since the dawn of plants, vs an indoor environment with lights that carry very different properties than the sun.

hillbill · Mar 26, 2024

All breathers in a home will raise CO2 inside a bit.
Also, the last/first couple hours the color of sunlight is much different than midday. and light on cloudy days also is very blue.

Beeswings · Mar 26, 2024

Delps8 said:
PPFD at noon can hit 2300±µmol but that's only for a limited number of days, at certain latitudes, if the weather is good. Over the course of a growing season, PPFD/DLI is much lower.

Why the 1k level? That's pretty much the max sustained level that cannabis can tolerate in ambient CO2. The attached paper shows that researchers were able to grow at 1800µmol. Try as I might, I haven't been able to get my grows to handle more than 1050-1100µmol and I've put a fair amount of time and money into optimizing a grow environment.

I'd be interested in your results.

He measured the sun just days after the spring equinox, it's safe to say he will have these light levels or higher the entire growing season.

ProPheT 216 · Mar 26, 2024

Tolerance Break said:
It's no different than indoors.

The plant needs co2 for photosynthesis. Indoors, they are often limited by the air in the lung room and the fans exchanging air. Running co2 is inefficient without a sealed set up, but you can push them much harder.

Outdoors, there is ample co2 in a sealed environment, it just so happens that it's earth's atmosphere, so they can get pushed harder. Spectrum might play a roll too, but I'm providing the most layman explanation I can because I'm not a scientist.

This is why I don't understand fan timers. I leave my fan exchanging air all the time and push my plants hard

hillbill · Mar 26, 2024

Bud Rot tells me to get the air changed constantly

igna · Mar 27, 2024

Con HPS, las plantas pueden aceptar una mayor densidad de fotones que con LED sin mostrar deficiencias ni signos de estrés en las hojas.

Para mí el problema está en el espectro LED (especialmente la falta de IR) y la relación de los colores entre sí.

Los científicos utilizan el NDVI para determinar los índices de vegetación. Esta fórmula indica la reflectancia infrarroja y la absorción del rojo intenso.

English translation (please post just the english only, thanks):
With HPS, plants can accept a higher density of photons than with LEDs without showing deficiencies or signs of stress in the leaves. For me the problem is in the LED spectrum (especially the lack of IR) and the relationship of the colors to each other. Scientists use NDVI to determine vegetation indices. This formula indicates the infrared reflectance and deep red absorption.

Delps8 · Mar 27, 2024

Beeswings said:
He measured the sun just days after the spring equinox, it's safe to say he will have these light levels or higher the entire growing season.

That's great to hear.

I know that's not the case in the US. Well, according to the DLI maps for the US, that's not the case. Below is a DLI map of CONUS from this site. An interesting pattern appears to be that, the further north you go, the lower the DLI. That may change once we get north of the border but I'd be at a loss to understand why.

The grower is at 55 north. I selected a location in Alberta and dropped the following grid location

55.10078308452325, -117.08076152550427

Into this web site.

DLI Calculator

This web app has been designed to help you determine daily light integral (DLI) values throughout the year for any location on Earth. It uses worldwide weather station data and algorithms to deliver the most accurate...

dli.suntrackertech.com

Below is a screenshot of the page that's rendered:

Reviewing the data, June has the highest DLI and that's just under 45 mols. As expected DLI is lower in the Spring, rises in the Summer, and falls in the…Fall.

I'm at a loss as to how what you say can actually be true but, who care, that's great for Moflow.

Delps8 · Mar 27, 2024

igna said:
Con HPS, las plantas pueden aceptar una mayor densidad de fotones que con LED sin mostrar deficiencias ni signos de estrés en las hojas.

Para mí el problema está en el espectro LED (especialmente la falta de IR) y la relación de los colores entre sí.

Los científicos utilizan el NDVI para determinar los índices de vegetación. Esta fórmula indica la reflectancia infrarroja y la absorción del rojo intenso.

English translation (please post just the english only, thanks):
With HPS, plants can accept a higher density of photons than with LEDs without showing deficiencies or signs of stress in the leaves. For me the problem is in the LED spectrum (especially the lack of IR) and the relationship of the colors to each other. Scientists use NDVI to determine vegetation indices. This formula indicates the infrared reflectance and deep red absorption.

Using LED's researchers have demonstrated that cannabis will grow in ambient CO2 at 1800µmol. Amazing to think that HPS can go even higher.

Could you post a link to the research?

igna · Mar 28, 2024

Do you think the spectrum used in this study is a good one?

Beeswings · Mar 28, 2024

Delps8 said:
That's great to hear.

I know that's not the case in the US. Well, according to the DLI maps for the US, that's not the case. Below is a DLI map of CONUS from this site. An interesting pattern appears to be that, the further north you go, the lower the DLI. That may change once we get north of the border but I'd be at a loss to understand why.

View attachment 5381587

The grower is at 55 north. I selected a location in Alberta and dropped the following grid location

55.10078308452325, -117.08076152550427

Into this web site.

DLI Calculator

This web app has been designed to help you determine daily light integral (DLI) values throughout the year for any location on Earth. It uses worldwide weather station data and algorithms to deliver the most accurate...

dli.suntrackertech.com

Below is a screenshot of the page that's rendered:

View attachment 5381588

Reviewing the data, June has the highest DLI and that's just under 45 mols. As expected DLI is lower in the Spring, rises in the Summer, and falls in the…Fall.

I'm at a loss as to how what you say can actually be true but, who care, that's great for Moflow.

Everything you posted supported my statement. No surprise that the summer solstice surround June 21 would have the most DLI of any day. It's the longest day... Of course this info would only be for the northern hemisphere.

hillbill · Mar 28, 2024

DLI is all those photons piled up like a cumulative effect of light intensity

Delps8 · Mar 28, 2024

Beeswings said:
Everything you posted supported my statement. No surprise that the summer solstice surround June 21 would have the most DLI of any day. It's the longest day... Of course this info would only be for the northern hemisphere.

I did not specify the number I was referring to and I should have. The number I was referring to was 2383 and I made the assumption that was the number in question. The idea never occurred to me that there would be any issue with 813µmols.

My apologies for being unclear.

Flower light question.

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