DLI and PPFD Questions???

[olegren]

I'm new as well but this is what hlg suggested I use when I emailed them.
Hlg ppfd calculator

+1. I have always gone by HLG recommendations since I'm growing with their lights. I use their chart as a reference & threshold for various phases, but beyond that I let the plant tell me if it wants more or is getting too much.

I try and keep seedlings right at 100ppfd until the second node or so unless I am seeing absurd stretch - then I will go as high as 200.

After a couple nodes, I start ramping up 2-3k lux each day until I'm at 400.

I stay at 400 until the first signs of preflower; then start the same incrementing process until I hit 800ppfd or see signs that there's light stress.

 

[Mañ'O'Green]

I run about 25 DLI from seed to transplant ~ 7 days. Then one day after transplant I start ramping up the light over a couple of days I will be up to the 50 DLI. I can go higher but there is no measured gain in yield for me. So yes 50 DLI for the grow from transplant to harvest. Don't forget the UV I am adding and that is not in the DLI calculations. So it may be a bit higher.

 

[Cerebral Goo]

+1. I have always gone by HLG recommendations since I'm growing with their lights. I use their chart as a reference & threshold for various phases, but beyond that I let the plant tell me if it wants more or is getting too much.

I try and keep seedlings right at 100ppfd until the second node or so unless I am seeing absurd stretch - then I will go as high as 200.

After a couple nodes, I start ramping up 2-3k lux each day until I'm at 400.

I stay at 400 until the first signs of preflower; then start the same incrementing process until I hit 800ppfd or see signs that there's light stress.

Thanks, will maybe try that next round and see how it works. Would like to try 4-5 light scenarios to see what works best

 

[Modernviking]

Anytime I try and lower my HLG 300l below 24" I start to get stress but my DLI at that height is garbage. Everything is bulking up hardcore despite that so maybe I'll never know lol.

 

[CannabisMingus]

o yes 50 DLI for the grow from transplant to harvest. Don't forget the UV I am adding and that is not in the DLI calculations. So it may be a bit higher.

@Mañ'O'Green - quick question. You do not run CO2 correct? Thanks for clarifying man.

 

[Mañ'O'Green]

@Mañ'O'Green - quick question. You do not run CO2 correct? Thanks for clarifying man.

No I do not run Co². I tried it twice. You need a mini-split AC in the grow room otherwise it just won't work. It was time consuming even with automated controls and the damn Co² bottles always ran out when there was no place open to refill them.

 

[Delps8]

I run about 25 DLI from seed to transplant ~ 7 days. Then one day after transplant I start ramping up the light over a couple of days I will be up to the 50 DLI. I can go higher but there is no measured gain in yield for me. So yes 50 DLI for the grow from transplant to harvest. Don't forget the UV I am adding and that is not in the DLI calculations. So it may be a bit higher.

I've got GG autos in early seedling stage, using a Vipar Spectra XS-1500. Like a lot of posters here, I've been hesitant to ramp up the light level so I really appreciate you sharing your experience and expertise. I just now upped the PPFD to 300 µmols @18/6 ≈ 20 moles.

Also, based on your postings, I just placed an order for a Royal Blue Veg Puck and should have it in the tent late next week. Many thanks for the info that you're passing along.

 

[GinFizzLuv]

Anytime I try and lower my HLG 300l below 24" I start to get stress but my DLI at that height is garbage. Everything is bulking up hardcore despite that so maybe I'll never know lol.

This has been an issue for me. Most recent grow I had lights maybe 18” from top of canopy, running DLI in low 40’s, lights on 24 hrs and got light burn on most of the upper fan leaves. Once I backed off to 24” and DLI 35-40 it stopped. Next run I’m going to go back to 20/4 and try 40’s DLI with light at 24”.