250-500umol too much for veg?

[PicklesRus]

Just wondering. I habe a really short veg tent to grow plants to a maximum height of 2' including the pot. Ill be using big pots but cut low to gain some extra space.

I know it all sounds rediculous but you gotta do what you gotta do if you know what I mean.

My par meter reads 250 at the soil and 550 at the max canopy height.

Is that way too much light for veg? Does anybody know? Ill find out if they get bleached or stressed. My clones curled up at the leaves. What other signs would tell me I have too much light?

Thank you everyone in advance.

 

[Photon Flinger]

You are fine.

If space is an issue, you can run 12/12 from seed. The plant doesn't begin to flower until it matures anyhow. If you give it enough light like you are then you achieving the same outcome without any guesswork.

1 DLI is 278 PPFD for one hour so around 550 will get you 24 DLI with 12/12. That is more than 12 and less than 65 DLI which have been suggested as a range all over a bunch of forums and studies.

 

[Rahz]

I had really good veg results with 450 so I think 550 will be a solid veg intensity.

 

[PicklesRus]

You are fine.

If space is an issue, you can run 12/12 from seed. The plant doesn't begin to flower until it matures anyhow. If you give it enough light like you are then you achieving the same outcome without any guesswork.

1 DLI is 278 PPFD for one hour so around 550 will get you 24 DLI with 12/12. That is more than 12 and less than 65 DLI which have been suggested as a range all over a bunch of forums and studies.

I never thought of achieving dli by reducing daily light output. 12/12 doesnt kick it into flower?

 

[PicklesRus]

I had really good veg results with 450 so I think 550 will be a solid veg intensity.

You are fine.

If space is an issue, you can run 12/12 from seed. The plant doesn't begin to flower until it matures anyhow. If you give it enough light like you are then you achieving the same outcome without any guesswork.

1 DLI is 278 PPFD for one hour so around 550 will get you 24 DLI with 12/12. That is more than 12 and less than 65 DLI which have been suggested as a range all over a bunch of forums and studies.

Thanks guys. Ill let y'all know how it goes.

 

[Photon Flinger]

I never thought of achieving dli by reducing daily light output. 12/12 doesnt kick it into flower?

Won't flower until it matures which if all goes well can be a few weeks or longer than a month. Strain dependent.

But going 12/12 with enough light is basically the fastest you could get a plant start to finish.

 

[heckler73]

1 DLI is 278 PPFD for one hour so around 550 will get you 24 DLI with 12/12. That is more than 12 and less than 65 DLI which have been suggested as a range all over a bunch of forums and studies.

By any chance are these 'studies' you refer to published formally? Or are you referring to something else?
What I am hoping for is a recommended title, if you have one off hand. It's okay if not...I'm just curious about this topic because I have not heard of this 'DLI' acronym before.

 

[PicklesRus]

By any chance are these 'studies' you refer to published formally? Or are you referring to something else?
What I am hoping for is a recommended title, if you have one off hand. It's okay if not...I'm just curious about this topic because I have not heard of this 'DLI' acronym before.

lol better get reading.

Ya Photon did you just make DLI up? Whats that mean, Da Light Intensity?

 

[mefunky]

Daily light integral I can't post links but Google has the answer.

 

[wietefras]

DLI and PPFD are not units of measurement. DLI just means the sum of photons received over a day. It's expressed in mol/day/m2 just like PPFD measurements are expressed in umol/s/m2.

You really should not put your vegging plants on a 12/12 schedule unless you intend to run the 12/12 system. You will lose control over how long you can veg since they will start flowering automatically upon reaching maturity.

 

[heckler73]

Daily light integral I can't post links but Google has the answer.

Ahhh, that makes sense. Thanks for the input, that helps... here's an abstract from which Wiki bases its page:

Daily light integral (DLI) describes the rate at which photosynthetically active radiation is delivered over a 24-hour period and is a useful measurement for describing the greenhouse light environment. A study was conducted to quantify the growth and flowering responses of bedding plants to DLI. Eight bedding plant species [ageratum (Ageratum houstonianum L.), begonia (Begonia ×semperflorens-cultorum L.), impatiens (Impatiens wallerana L.), marigold (Tagetes erecta L.), petunia (Petunia ×hybrida Juss.), salvia (Salvia coccinea L.), vinca (Catharanthus roseus L.), and zinnia (Zinnia elegans L.)] were grown outdoors in direct solar radiation or under one of three shade cloths (50, 70 or 90% photosynthetic photon flux (PPF) reduction) that provided DLI treatments ranging from 5 to 43 mol·m–2·d–1. The total plant dry mass increased for all species, except begonia and impatiens, as DLI increased from 5 to 43 mol·m–2·d–1. Total plant dry mass of begonia and impatiens increased as DLI increased from 5 to 19 mol·m–2·d–1. Impatiens, begonia, salvia, ageratum, petunia, vinca, zinnia, and marigold achieved 50% of their maximum flower dry mass at 7, 8, 12, 14, 19, 20, 22, and 23 mol·m–2·d–1, respectively. The highest flower number for petunia, salvia, vinca, and zinnia occurred at 43 mol·m–2·d–1. Time to flower decreased for all species, except begonia and impatiens, as DLI increased to 19 or 43 mol·m–2·d–1. There was no consistent plant height response to DLI across species, although the shoot and flower dry mass per unit height increased for all species as DLI increased from 5 to 43 mol·m–2·d–1. Guidelines for managing DLI for bedding plant production in greenhouses are discussed.

 

[sethimus]

By any chance are these 'studies' you refer to published formally? Or are you referring to something else?
What I am hoping for is a recommended title, if you have one off hand. It's okay if not...I'm just curious about this topic because I have not heard of this 'DLI' acronym before.

better get studying then...

 

[PicklesRus]

better get studying then...

Hehe "da light intensity"

 

[Photon Flinger]

lol better get reading.

Ya Photon did you just make DLI up? Whats that mean, Da Light Intensity?

Nah day light integral has been around in agricultural research for very long time. Was further explained in a post above.

What it let's us do is compare light exposure from different sources. With daylight, the PPFD changes throughout the day and DLI is easier to work with then doing a bunch of stupid calculations for accuracy that isn't necessary.

As for 12/12 losing control, I would disagree, it gives you more control. LST and other training techniques can still be used to keep the plan in a limited space. All a personal preference but if you have enough light, no reason you can't run 12/12 comfortably.

 

[PicklesRus]

What is the dli range of cannabis?

 

[Photon Flinger]

What is the dli range of cannabis?

12-65

 

[PicklesRus]

12-65

Thank you! I will make a par map and calculate my tents dli

 

[PicklesRus]

Heres the 2'high veg tent for some eye candy. Thanks for the info guys.

Just for fun the pic below was the first version. A little too much light i think

 

[Photon Flinger]

No, that is probably fine so long as you keep the thermal temps low. The plants will peak out at their maximum rate with the rest of the energy above that going to waste as heat.

I have had fan leaves come close to cobs and get 3500+ ppfd without burning when the temps were kept under 27c. Apparently they are testing a lettuce with 5000+ ppfd.

Are you using a driver that you can dim with?