LED and Calmag issues.

gforce3 said:

The main thing a high vpd will effect is the uptake of calcium and magnesium. People think they have a calcium deficiency add more calcium. Don’t do this, it makes it worse. If you have problems with a high vpd or if you don’t know what that is. If you have for example 80 degrees temp and 45% humidity your vpd is to high meaning your plants will not intake nutrients and water the proper way. If you want a quick fix with a high vpd lower your nutrients drastically so they uptake more water than nutes. Lower your calmag and the ppm of your nutes and this will help the plant survive. Im
Not the best at explain these things but I hope you understand what I’m getting at. You can also lower the output or dim your lights, that will also help with a high vpd. High powered LED lights with a high vpd is a recipe for death. Same goes for HPS but the infrared will help open the stomata of the plant leaf. I hope this helps and I hope I explained it right. I know how some of you feel when a grow isn’t going right.

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drsaltzman said:

I dunno man.
I’m no master grower but these plants have been chugging along under COB LEDs in 78-80° and humidity never lower than 45%. They are nowhere near certain death. Well let me rephrase that. There’s certain death in their future but I control that. Flipped the lights Sep 10. Stopped stretching around Oct 1. So they’re 4 weeks into flower if you count those things.

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drsaltzman said:

I’m a minimalist.
3 gallon felt pots.
Roots 707.
300w COB in a 2x4 tent.
GH Floranova Bloom all the way through.
Tap water.
I use Recharge every other feed.
And a little Mykos in the transplant hole.
Very rarely run into trouble.
Haven’t used Calmag in years.
If you can grow, you can grow.
Your plants aren’t gonna die under LEDs because your humidity is 40% and your temp is 80°F.

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Tangerine_ said:

You explained that fine.

Thing only thing I'd add is it IS possible to grow in low pressure and have a healthy harvest but it requires a grower to really have feel for their environment. I've seen growers pull off some healthy resinous plants with the right knowledge and grow strategies, ie, anticipating seasonal changes and adjusting watering and fertigation methods.

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Three Berries said:

I can defiantly see leaf curl when the VPD gets over 1.2 in my tent. Granted the LEDs are not the best but it's obvious. And it's much more pronounced on the OG Kush vs the GDP. These LEDs I'm using in the tent really suck though.

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speedwell68 said:

Which LEDs are they? I also have some OG Kush, just potted it up and started LST. I am vaguely curious about all of this.

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gforce3 said:

Totally agree . What I’ve learned is lowering the nutrients with a high vpd or dry environment will make a successful grow. It’s just much easier with a perfect vpd and will reward the grower with a heavier yield. Wish you all the best

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jarvild said:

View attachment 5022931View attachment 5022932View attachment 5022933
Something wrong with these never paid attention to VPD plants, grown under LED's ?

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jarvild said:

View attachment 5022931View attachment 5022932View attachment 5022933
Something wrong with these never paid attention to VPD plants, grown under LED's ?

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Three Berries said:

Did you ever turn them or were they always in the same spot?

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gforce3 said:

you guys are a piece of art. Just because you haven’t checked your VPD doesn’t mean your vpd is out of wack. Just because you don’t check vpd doesn’t mean you’re going to fail. Grower talent is the most important thing. We are all right and I’m not bashing anyone. Some people know from experience how to keep a grow room in check. I’m not disagreeing with anyone. All I’m putting out there are ways to make it easier for the inexperienced grower. Following a VPD chart will make life easier for anyone it’s scientifically proven.
there are so many factors
Light intensity
Temperature
Humidity
Leaf temperatures
Nutrient EC

with out checking vpd a good grower knows lower light intensity, lower nutrients etc. you can adjust from there as the plants talk to you. No way is the wrong way. But following VPD def makes it easier for the inexperienced. You guys are so quick to get insulted without thinking about what people are trying to get across. No one was attacked or called out just information that should be learned. I know it’s hard this day in age with all you soft ass sensitive mfers. With you all the best. Happy growing!

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strongbow19 said:

Would just like to say that this is one of the most informative threads on LED growing on the whole internet.

I recently started up a grow and had between 18 C and 20 C throughout the 4 weeks veg and they started showing heavy tiger stripes and the start of brown spots a few days ago, and I went out and bought a heater after discovering this thread. I am now having day time temps of around 25 26 max and running the exhaust on stop and go to reduce usage of heater and also have the heater on a temp controller and then keeping the humidity between 62 and 76 during the day. 17 degrees and 60 humidity at lights off.

But now, after I changed the environment up a bit like mentioned above they are now getting burned tips and also their EC runoff is now a bit higher than the input, where it literally was the opposite when I ran the low shit temps I would give 1.6 EC and they would have a run off 1.3. Now it's 1.5 input and 1.7 1.8 run off. I saw a comment on here that a guy also had opposite reaction on EC when he tuned his VPD for the better.

Temp of leaf surface is 1 degree less than ambient.

They are clones from mothers that was fed 1.6 EC all their life.

My question is why? I thought they would now embrace even more light and use better nutes. (Not that I changed the light distance or anything.)

Never thought I'd have so many pit falls staring up a LED grow room and so many things to buy, it's sad really.
Have been growing outdoors in 100% coco since 2014. Have never tried my hands at indoor.

What should I do now, any input would be appreciated.

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strongbow19 said:

Would just like to say that this is one of the most informative threads on LED growing on the whole internet.

I recently started up a grow and had between 18 C and 20 C throughout the 4 weeks veg and they started showing heavy tiger stripes and the start of brown spots a few days ago, and I went out and bought a heater after discovering this thread. I am now having day time temps of around 25 26 max and running the exhaust on stop and go to reduce usage of heater and also have the heater on a temp controller and then keeping the humidity between 62 and 76 during the day. 17 degrees and 60 humidity at lights off.

But now, after I changed the environment up a bit like mentioned above they are now getting burned tips and also their EC runoff is now a bit higher than the input, where it literally was the opposite when I ran the low shit temps I would give 1.6 EC and they would have a run off 1.3. Now it's 1.5 input and 1.7 1.8 run off. I saw a comment on here that a guy also had opposite reaction on EC when he tuned his VPD for the better.

Temp of leaf surface is 1 degree less than ambient.

They are clones from mothers that was fed 1.6 EC all their life.

My question is why? I thought they would now embrace even more light and use better nutes. (Not that I changed the light distance or anything.)

Never thought I'd have so many pit falls staring up a LED grow room and so many things to buy, it's sad really.
Have been growing outdoors in 100% coco since 2014. Have never tried my hands at indoor.

What should I do now, any input would be appreciated.

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Nutty sKunK said:

More heat = more transpiration. More transpiration means more water(nutrients) being pulled into the leaves.

Has your humidity changed at all since increasing ambient temps?

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strongbow19 said:

Thanks man so how do I approach this situation, what must I do? Lower EC or what?

I couldn't remember what the humidity was before the changes probably around mid 50s, but now like I said am running between 62 - 75 humidity by keeping the exhaust fan on a start stop to keep up the temps more for the measly 420watt heater I have. Plants are week 5 veg.

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