Flip to flower...lighting intensity increase, please explain as I have no experience past veg stage

Renfro said:

I should also mention that different strains will like different lighting intensities. I mainly sort them into two categories, ones that like it bright and ones that like it really bright. lol

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Thanks again this a huge help.

What is your maxed out umols roughly with the hps on full?

I also appreciate the point about 2 groups, lol bright and brighter.

How do you handle the 2 groups...do the highest (!) ones go in the middle?

ComfortCreator said:

Hi Dank,

Im using lux only because its what I can measure. Its my understand/guess that with 3500k lights my conversion is roughly 58lux per umol...so for example when fluence says 300 to 600umols in veg, i convert that range to be 17.5k to 35k lux.

Dr meter can measure lux. Ive read about all this stuff endlessly, but reading and doing are most definitely different experiences. Please share anything you think may help.

How to increase lighting in transition...
How much ventilation a grow really needs...

Is a much, much shorter version of my original post!

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Understandable, I'm pretty sure MIGRO@youtube made a formula to convert lux to par if you want to check it out.
Here is a rough idea on PAR for different stages:

Seedlings - 250
Mid veg - 450
12/12 swap - 500
Mid flower - 750
Mid-late flower - 850
Last 2-3 weeks - 400


As for ventilation, it's said you want to exchange the air fully every couple minutes or so and there is a cfm calculator somewhere on google but in reality depending on size of space as long as you have a proper exhaust fan running you'll be golden assuming you have temp/humidity dialed in the suit. just to add, having multiple fans is just as important as air exchange, I run 4x in a 4x4. And then you have to take into account CO2 intake, that will effect intensity they are able to take.

Renfro said:

I should also mention that different strains will like different lighting intensities. I mainly sort them into two categories, ones that like it bright and ones that like it really bright. lol

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This is very much true, which is another reason being able to dim intensity is clutch these days. Some cookie crosses in particular I've heard are sensitive.

DankNoTill said:

This is very much true, which is another reason being able to dim intensity is clutch these days. Some cookie crosses in particular I've heard are sensitive.

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In the old days all we could do is raise the light. Dimmable ballasts and LED's rock.

ComfortCreator said:

What is your maxed out umols roughly with the hps on full?

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Depends on the bud, some are closer than others but it's DE HPS at full intensity (1150 watts).

ComfortCreator said:

How do you handle the 2 groups...do the highest (!) ones go in the middle?

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I either give them their own row or if it's just a plant or two I put them in one of my odd ball spots. You'd have to checkout my journal to really understand.

Renfro said:

In the old days all we could do is raise the light. Dimmable ballasts and LED's rock.

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Does dimming the ballast on a 1000 watt bulb change the light spectrum?

DankNoTill said:

Understandable, I'm pretty sure MIGRO@youtube made a formula to convert lux to par if you want to check it out.
Here is a rough idea on PAR for different stages:

Seedlings - 250
Mid veg - 450
12/12 swap - 500
Mid flower - 750
Mid-late flower - 850
Last 2-3 weeks - 400


As for ventilation, it's said you want to exchange the air fully every couple minutes or so and there is a cfm calculator somewhere on google but in reality depending on size of space as long as you have a proper exhaust fan running you'll be golden assuming you have temp/humidity dialed in the suit. just to add, having multiple fans is just as important as air exchange, I run 4x in a 4x4. And then you have to take into account CO2 intake, that will effect intensity they are able to take.

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Thank you so much! This is gold for a newbie like me. It lays out a rough path from seed through flower. You gents have so much experience you may not realize that gap exists!

Im thrilled to see im right in line with flip to 12 12.

Ventilation ive learned quickly (i think) i have 2 fans up high blowing down over the heatsinks and power supplies, one rotating a nice breeze across the girls and one blowing at a wall that had condensation.

I cant really guess how much the carbon filters slow the exhausts but i have fan power roughly 400cfm for a room thats about 225cft. Im at 40% continuous now, up from 30% a week ago. I figure if carbom cuts flow 50% im still exchanging every 2 min or so. Im guessing in later flower i need more airflow.

Again Dank and renfro much thanks for your time. You have saved me from several mistakes with your posts.

ComfortCreator said:

Im thrilled to see im right in line with flip to 12 12.

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Just remember, everyones grow is a little different so use others numbers as a guideline and most importantly, watch your plants for signs. They will tell you what they like.

Renfro said:

Just remember, everyones grow is a little different so use others numbers as a guideline and most importantly, watch your plants for signs. They will tell you what they like.

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Renfro thank you. Ive read many threads with your advice and value it greatly. I saved about a dozen opinions in a folder of potential umol levels, fluence, RQS, GWE and about 10 posters who have great reputations. The ranges were clear but i could not wrap my head around how fast it ramped up. For some reason i had the impression going from 24 0 or 18 6 to 12 12 allowed for a lot more light, perhaps the measure mentioned earlier...DLI...and allowed it to be done almost instantly. I am very glad i asked...a real risk i would have fried them for a few days before seeing rhe problem.

ComfortCreator said:

Im not trying to be a dick but no, he didnt. I know i have to increase the intensity, Im looking for how fast it is done ...

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You have a big brain, sir, so naturally you question the method.
No one questions flipping from 18 to 12 hours in one swoop, but they should. It stresses plants.
And you are right to question sudden intensity increase.
Think about how Spring and early summer afternoons are bright but not pounding light at us. Late summer afternoon light can be oppressive by comparison.
How to simulate this change indoors? You can’t, but you can approximate it somewhere between a hard flip and tiny increments, as in nature.
You say you have dimmer; crank it up a few points every day until you reach target. Take a week or two to make the change.
I can’t say definitively this is more effective than a hard flip, but it makes sense to me also.
Enjoy the process and your harvest!

Father Ramirez said:

You have a big brain, sir, so naturally you question the method.
No one questions flipping from 18 to 12 hours in one swoop, but they should. It stresses plants.
And you are right to question sudden intensity increase.
Think about how Spring and early summer afternoons are bright but not pounding light at us. Late summer afternoon light can be oppressive by comparison.
How to simulate this change indoors? You can’t, but you can approximate it somewhere between a hard flip and tiny increments, as in nature.
You say you have dimmer; crank it up a few points every day until you reach target. Take a week or two to make the change.
I can’t say definitively this is more effective than a hard flip, but it makes sense to me also.
Enjoy the process and your harvest!

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Well said Father (lol esp about the big brain)

You make great points, and as I think about natural outdoor lighting, it would seem the lighting intensity would lessen theoughout flower in the natural world...after the solstice it lessens to the point where trees outside (at least in cold environments) decide its better to drop their leaves then support them further....hmmmm....

That does mirror what i read about plants dropping their leaves at the end of flower...but i cannot grasp how we increase intensity in flower when nature is naturally reducing it....? Ot perhaps intensity remains similar, but temperature conditions are what change.

So much i dont know. Im greatly enjoying this journey! Thank you for the thoughtful post.

I increase during veg, am at full in flower and taper it off at the end. Tapering light intensity at the end gives me better yields, denser buds and eliminates fox tailing on many strains.

ComfortCreator said:

.... but i cannot grasp how we increase intensity in flower when nature is naturally reducing it?

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Intensity of the warmer spectrums increases late in summer and autumn even though each day the plant receives a few minutes less light.
I can’t say I understand why, but thats what happens. This is why we use 6000k to veg and 2700k to flower. If we were going to take the concept of incremental change further, we’d switch our spectrum more slowly from veg to flower, but most people simply flip.

Another contradiction is that we generally strive to not stress our plants, but employ training techniques that most definitely stress them, and many growers say it is precisely the correct amount of stress that creates the most potent flowers and biggest yields.

Father thank you for filling in some blanks. From all my reading (and full disc, no experience), everybody who is a "pro" does seem to agree that stressing the plants is a good thing.

Perhaps the word stress is a misnomer. In human physiology, we stimulate growth by challenging our bodies to do more than it did before, and in doing so effect a change that can improve our condition.