So I understand that when you send your plant into Flower by changing the light cycle you lower your DLI. But it shows it increasing over the next few weeks as well. But it never gets above the high point in the vegetative state. I always thought you’re supposed to increase your light intensity during the flowering stage.
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You don’t have to lower your DLI when you switch from 18/6 to 12/12. You can increase the intensity of the light enough to make up for the lost hours.
Here’s two different ways to achieve the same DLI.
600 PPFD over 18 hours is 38.88 DLI
900 PPFD over 12 hours is 38.88 DLI
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DLI is a mathematical formula, In veg state the time in the formula is 18, when switched to flower that number is cut by 1/3 to 12. I believe that the chart shown has the light fixture at the same wattage and height for the last week of veg and the first week of flower. Then increasing the light wattage and/or moving it closer to the plants some amount once a week. I think @Cap_Ron explained it better than me.
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But according to the Chart you lower your DLI before you send them into flower. That’s what wasn’t making sense to me
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You do. That’s how to keep the DLI when you cut the hours back. This chart eases the plants into the increased PPFD over weeks. Some advocate for just jacking the light up to full intensity at time of hour decrease to hold DLI levels right away.
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No you don’t. The DLI lowers itself when the hours are cut back and the intensity remains the same.
So you really do, but by cutting the hours…
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Here is a chart that maybe a little more straightforward.
Here is a chart that I made for my HLG 350 with the Diablo boards. I start by reading light level at the canopy in Lux then use the chart to adjust the light dimmer. HLG has calculators on their website that can help you obtain the correct DLI for you light. You will notice that at 45,000 Lux the output will not need to change at the flip. Since the change from 47 to 32 DLI is fairly close to what the chart recommends. Not all lights are created equal so you will need to get a good accurate DDLF reading from your light.
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Sort of what I do. I run my plants from mid veg though flower at 1,000 PPFD. The DLI decrease at 12/12 is unavoidable.
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600 ppfd at 18 hours is 38.9 DLI. 600 ppfd at 12 hours is 25.9 DLI. The amount of light didn’t change, just the number of hours.
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I see thank you
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Would you say you’re running ~43 DLI, mid-veg to harvest then?
Would you run an 18/6 auto the same…~660 PPFD/~43 DLI?
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I’ve never calculated DLI. PPFD is sufficient to be aware of the proper lighting level.
You want your PPFD higher if in flower.
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I think the chart is counting flip/transition week as the last one in veg. They switched to 12/12 which explains the drop, but they labeled it as veg since it usually takes around a week to see some buttons. Thats my best guess
I just use the ppfd reading. I dont like to over think too much.
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[quote=“MidwestGuy, post:12, topic:105028, full:true”]
I’ve never calculated DLI. PPFD is sufficient to be aware of the proper lighting level.
…Sorry, genuinely interested in the answers but maybe I’m not asking questions the correct way. I’m asking because I seek the simplest method, which I thought was DLI since it takes into account hrs/day and PPFD; but your response implies that just PPFD is necessary for the simplest method of getting proper lighting, and I’m overcomplicating this?
Is there something simple for just PPFD that lists hours a day for autos, that is simpler than a DLI chart such as this?:
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Yes.
Seedling PPFD: 300
Veg PPFD: 600
Flower PPFD: 800+
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18/6, seed-to-harvest, for autos?
Yes. 12/12 is not necessary for autos. 18/6 maximizes DLI.
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Thank you, that’s the most succinct answer for lighting I’ve seen in a while, aligns with a ~19>39>52+DLI schedule, and could be used with just the specs for one’s light if it is one that was publicly tested/published for PPFD numbers, which most decent ones seem to be. I think this is an area that new growers struggle with; more than experienced growers realize.
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