The Gee Spot - You Finally Found It

[Gee64]

i like using this chart for VPD

VPD Charts in Fahrenheit and Celsius With Leaf Temperature

We made some easy-to-use VPD charts for both Celsius and Fahrenheit, for clone, veg, and flower stages. Hope you find them useful. For more information about VPD, and to make your own custom charts, check out our VPD Guide. VPD Charts for Fahrenheit VPD Chart for Clones in Fahrenheit -2F...

pulsegrow.com

There's a link to a good guide in this post too. Thanks Con

 

[Kaldean]

If you google VPD you will get ons of info on it. You want the info on VPD that deals in RH, air temp, and leaf temp. VPD that only deals in RH and air temp is for weather forcasting, not growing plants.

@Gee64
Iv just got the dr greenhouse one, the pulse one I’m lost with, and iv put in my temp and rh, and like you say, when I calculate, it’s saying dry and stressed , I think it was on about me thou to be honest
But when I put in the one with leaf temp, that iv guessed at, cos I see someone mention 6 degrees lower
it’s saying I’m ok
But Gee, you know it’s coming don’t ya
Howd I measure leaf temps
And iv just realised my tents hot

 

[Kaldean]

Play around with it Kal. Run some scenarios in the app. Then decide what variables are hard to change, such as ambient room temp, and adjust the other 2 parameters in the calculator.

If you look at this that I posted for Azi you can see at the bottom what your targets are for the stage of the grow you are in.

Leaf temp is the tricky one. If you raise room temp it will also raise leaf temp but if both go up 1 degree not much difference is noticed. Like this

raising both did raise VPD but if room temp stayed at 90 and you only raised leaf temp by 1 degree you would get this

which is a much greater rise in VPD.

To raise leaf temps to close the gap on air temps, you add more light and the radiation in the light excites molecules in the leaf just as exercise does in our muscles, and heat is formed.

You need to be careful you don't light burn the leaves so don't get carried away, but once you calibrate your PPFD app you can guard against that.

A healthy plant under optimal conditions will try to get to 2 degrees under room temp after 10 hours of lights on. That is where optimal transpiration occurs.

It's important that you take your readings late in the plants day as they are all over the place in the mornings. You want readings from when the plant is working it's hardest or you may end up over revving your plants late in the day. Never react to earlier readings. Always from the 10 hour mark.

Then there is RH. Once your light is set properly to your room temp you can speed up or slow down the plant by lowering or raising RH.

It's not as complicated as it sounds if you run some scenarios in the app before you start actually adjusting things in the grow room.

Right now in my grow when the plants stretch and PPFD hits 1100 the leaf temp differential is 2 degrees, and when I drop it back to 950-1000 PPFD it goes to a 3.5 degree differential which tells me she may be able to handle 1100 PPFD, but I will wait until stretch finishes and she stops growing taller before I sneak in on that one, as I don't want to burn my leaves or yield and quality will suffer.

VPD is an extremely powerful tool. It's actually the difference between outdoors and indoors. Outdoors you get what nature dictates.

It surprises me that it isn't followed and used by everyone. We all have lights and nutes, so environment is all thats left.

And as always, the proof is in the pudding so lets look at the pudding. We have all read/heard numerous times that in flower 76F is the ideal temp, and most would say that after stretch 48RH is perfect. Well if you toss 76 and 48 into the calculator with a 2 degree spread you get this...

and 1.4 is perfect VPD for flower after stretch. The plants are working hard but not too hard and you still have buffer room if conditions fluctuate.

So here is the warning. If you raise VPD too high the atmosphere will suck too hard on the plant and draw water in too fast at the roots. The water coming in will not contain adequate food as it's getting sucked in too fast, and a deficiency will occur, so try to stay under 1.5 always, and 1.4 in late flower is plenty.

Don't get greedy here. Over 1.4 and you are one RH drop or temp spike away from screwing up your grow for a few days until it recovers, and possibly damaging leaves that won't recover. That comes out in yield.

In a nutshell, it's the throttle for the grow.

Thank you @Gee64
There’s a lot there for me to go over to get a better understanding of it all, and your absolutely correct, if your growing weed and you understand this, it’s making it much easier in it, it’s a great tool that I need to learn, thank you mate for that run through

 

[Kaldean]

i like using this chart for VPD

VPD Charts in Fahrenheit and Celsius With Leaf Temperature

We made some easy-to-use VPD charts for both Celsius and Fahrenheit, for clone, veg, and flower stages. Hope you find them useful. For more information about VPD, and to make your own custom charts, check out our VPD Guide. VPD Charts for Fahrenheit VPD Chart for Clones in Fahrenheit -2F...

pulsegrow.com

Thank you @con for that link, now to get me head round it

 

[Gee64]

@Gee64
Iv just got the dr greenhouse one, the pulse one I’m lost with, and iv put in my temp and rh, and like you say, when I calculate, it’s saying dry and stressed , I think it was on about me thou to be honest
But when I put in the one with leaf temp, that iv guessed at, cos I see someone mention 6 degrees lower
it’s saying I’m ok
But Gee, you know it’s coming don’t ya
Howd I measure leaf temps
And iv just realised my tents hot

you need an infra red thermometer like this one

and you zap the highest mature leaves and get the leaf temps to plug into the calculator.

If you do it at about 10 hours after lights on you get the reading that is where they are at when working the hardest.

Not saying you should run out and spend money, but for how cheap they are they're worth it. This, a water stik, and a refractometer are my 3 main tools that I use all the time. Daily for the gun and water probe. I actually zap my leaves for temp every time I open the tent. A sick plant will suddenly run hot. So will a dry one.

 

[Gee64]

Thank you @Gee64
There’s a lot there for me to go over to get a better understanding of it all, and your absolutely correct, if your growing weed and you understand this, it’s making it much easier in it, it’s a great tool that I need to learn, thank you mate for that run through

You don't really need to know it deeply, just in general and then let the app do the work. You plug in values that you think you can achieve and see what you get before you make changes.

 

[Kaldean]

you need an infra red thermometer like this one

and you zap the highest mature leaves and get the leaf temps to plug into the calculator.

If you do it at about 10 hours after lights on you get the reading that is where they are at when working the hardest.

Not saying you should run out and spend money, but for how cheap they are they're worth it. This, a water stik, and a refractometer are my 3 main tools that I use all the time. Daily for the gun and water probe. I actually zap my leaves for temp every time I open the tent. A sick plant will suddenly run hot. So will a dry one.

Wow, big part of my life them and I didn’t even think of it
Thank you Gee

 

[Kaldean]

You don't really need to know it deeply, just in general and then let the app do the work. You plug in values that you think you can achieve and see what you get before you make changes.

@Gee64
That’s exactly my intentions, wing it, and the more I use it the better (hopefully lol) I will get with it
Could you do me a favour if you don’t mind please Gee, if I show you this pic, could you check yours just to see if the one iv got is roughly on track
And thank you again Gee for all the time you’ve spent trying to educate an idiot

 

[Azimuth]

It could be cold water, but likely it means you need more light to drive them harder.

No, not cold water and the ppfd is north of 1,000.

Or it could be that you need better ventilation to lower air temps. 90 is a bit high.

Yeah, I don't have any meaningful control of the environment, but I'll turn up the extract fan to see if I can lower temps a bit. I'd rather be mid 80's at the peak, but, you know...

What is the RH in your grow space?

Between mid 20's and mid 50's which I think is likely my issue. But no room for a humidifier...

Leaf temps drop quickly so you need to open your grow space and zap a leaf temp quickly.

Ok, makes sense. I'll try again tomorrow.

An RH of 55 is even better as it would get your VPD down to 1.33 which is a great sweet spot to avoid stress and leaves room for fluctuations.

I think that that mid 50's in rh is during lights out, and likely the mid 20's number is lights on. It was a steady 45 with the doors open but that's not typical obvs.

So close!

Remind us again please Azi, which mix is this?

This is the one with all of the mineral calciums but relying on flowers and nettle for much of the P value, so no bone meals, and growing in my first NetPot SIP.

 

[Gee64]

No, not cold water and the ppfd is north of 1,000.


Yeah, I don't have any meaningful control of the environment, but I'll turn up the extract fan to see if I can lower temps a bit. I'd rather be mid 80's at the peak, but, you know...


Between mid 20's and mid 50's which I think is likely my issue. But no room for a humidifier...

So your VPD is likely over 2. You really need either humidity or lower air temps but really you need both. Oh well it is what it is.

In theory less light to lower the leaf temp down to 80 would put you in a better spot, but I have no idea how dim you would have to go so who knows if it would be any better.

Ok, makes sense. I'll try again tomorrow.


I think that that mid 50's in rh is during lights out, and likely the mid 20's number is lights on. It was a steady 45 with the doors open but that's not typical obvs.


This is the one with all of the mineral calciums but relying on flowers and nettle for much of the P value, so no bone meals, and growing in my first NetPot SIP.

Ok good, I thought it was that one. If the line could still be fuzzier then I would start there. Get it as close to perfect as you can and hold it there thru a good weather high pressure stretch and see where it's truly at so you can adjust better on the next batch. Your really close now.

Do you have a good supply of flower crumbles and nettle and such?

 

[Gee64]

@Gee64
That’s exactly my intentions, wing it, and the more I use it the better (hopefully lol) I will get with it
Could you do me a favour if you don’t mind please Gee, if I show you this pic, could you check yours just to see if the one iv got is roughly on track
And thank you again Gee for all the time you’ve spent trying to educate an idiot

Mine says the same. The app I use is called "VPD Calculator" by cannafused life at the Google Play Store.

I think they should all work, they likely use the exact same formula.

If you are at 1.23 you have room to improve but not drastically. You're in a fairly good spot but if your PPFD meter says you can safely turn the light up a bit, a 1 degree increase in leaf temps would give you a 1.35 which is really close to optimal.

A 2 degree increase in leaf temps would be bang on at 1.46 but make sure your plants can handle that much light 1st.

Check the PPFD before you try increasing it.

1.46 is almost dangerous, personally I try not to go over 1.40 for extended periods.

 

[Gee64]

Some random outdoor shots in some cool evening skies.

and a bug.

 

[g-one-three]

Some random outdoor shots in some cool evening skies.

These are awesome shots! I really like that first one. Very photogenic plants.

 

[Gee64]

These are awesome shots! I really like that first one. Very photogenic plants.

Thanks G. The light was in a good spot.

 

[Carmen Ray]

Right, GJotM, sorry thats what I meant. Well dang, that's sucky. Will they allow you to ship it elsewhere and a member could buy it from you?

Thanks Gee. I don't let these kinds of things bother me. It is what it is. The competitions specify that prizes cannot be shipped to a third party.

These are awesome shots! I really like that first one. Very photogenic plants.

I agree!

 

[StoneOtter]

Just want to say thanks to @Gee64 and post these bud shots. This was the first grow that I started testing the Brix and @Gee64 giving me all the help and info. These buds are awesome and the trichomes are so pronounced. Without a doubt the best weed I've grown so far.

That's what we're looking for! Those are real sweet buds G! Nice work!

 

[Azimuth]

In theory less light to lower the leaf temp down to 80 would put you in a better spot, but I have no idea how dim you would have to go so who knows if it would be any better.

I could lower the pots to increase distance and reduce intensity, but the leaves are praying hard which, according to your plant turgor theory, suggests they like it where they are. The weather is turning cooler this week and temps should get back lower in the coming days so hopefully that, and turning up my extract fan, will help.

Do you have a good supply of flower crumbles and nettle and such?

I do, but I'm going to try the mineral versions of P for a couple of rounds. I got some bone meal and some fishbone meal which I added to the next round that's "cooking" (more like sitting) for a month before use. I'll add them to my top dressing mix as well as to the worms and see if that improves things.

I don't want to go too heavy since P seems like it can cause issues if provided in excess.

 

[Carmen Ray]

I'm fascinated by this plant's desire for light. I had it at 750 ppfd and @Jon suggested I turn up the lights so I did. It went to 900 ppfd and subsequently grew taller into 1300 ppfd and hasn't changed turgidity and posture. It is 7.5 inches from the light. This is kinda mind blowing to me. The plant shows no ill effect that I can tell, and appears happy and super erect lol. It's a light hog.

 

[Gee64]

I could lower the pots to increase distance and reduce intensity, but the leaves are praying hard which, according to your plant turgor theory, suggests they like it where they are.

They likely do. They have ways of adjusting.

The weather is turning cooler this week and temps should get back lower in the coming days so hopefully that, and turning up my extract fan, will help.

More air to cool, that's the best way

I do, but I'm going to try the mineral versions of P for a couple of rounds.

Sweet! Once that extra P gets into your closed loop of recycling and fortifies everything, then your flower crumbles and potions should be able to easily maintain it in your pots. As your inputs go up in brix and minerals so will your outputs, so share that bagged P with your outdoor inputs. Rock phosphate is an excellent outdoor long term slow release P that is really easy to apply to outdoor gardens.

I got some bone meal and some fishbone meal which I added to the next round that's "cooking" (more like sitting) for a month before use. I'll add them to my top dressing mix as well as to the worms and see if that improves things.

It will and once it recycles it will really start to show it's benefits.

I don't want to go too heavy since P seems like it can cause issues if provided in excess.

It can, but you need a very dense fast (for P) release kind, like SRP or a liquid P to really screw things up. As long as myco needs to mine it with the microbes help then it is fine. You just don't want the plant to be able to bypass the biology and uptake it on it's own. Bat guano is far safer than SRP. Stay away from liquid P.

You are almost there. Here is some food for thought.

Recycling soil is somewhat of a closed loop except you remove some for consumption.

Lets say you remove 2 ounces of flower per plant for example, then wouldn't replacing that with 2 ounces of dried garden flowers sort of balance it back?

Now garden flowers won't be as dense as flowers from a hyper accumulator like cannabis, so triple it. 2 oz out, 6 oz back in, and recycle the rest of the weed plant.

Don't forget the roots either, they are a heavy carbon source and very dense on innoculants.

Get a feel for restoring what you take out, and then if you think the plant that you harvested could have used more of anything, so lets say P again, to have turned out better, then add that on top of your 6 ounces of P flowers to restore the soil AND fortify it stronger than the last run. Track that.

So now lets say you are 2 oz out and 9 oz back in. If that works then you have a formula for success. If there is still room for improvement you have a base formula to improve on.

All that being said, these commercial inputs you are adding now could be looked at as a one time event if you fortify your base inputs with them and then trap them in the loop.

Make sense? Once your fortified then your system only needs to maintain, and the soil recycling becomes the re-fortifier.

Then keep track of overall maintenance additions and try to cook that much extra in in the recycling stage and see if you can get closer to a "water only" scenario.

Then EWC can really stand a chance as a top dress maintainer as it doesn't need to fortify and maintain.

 

[Gee64]

I'm fascinated by this plant's desire for light. I had it at 750 ppfd and @Jon suggested I turn up the lights so I did. It went to 900 ppfd and subsequently grew taller into 1300 ppfd and hasn't changed turgidity and posture. It is 7.5 inches from the light. This is kinda mind blowing to me. The plant shows no ill effect that I can tell, and appears happy and super erect lol. It's a light hog.

I'm not a light expert by any means, but dli is a valuable tool. In my mind its should actually be LLI, Lifetime Light Integral. Then divide the amount of light a plant uses in it's lifetime into daily amounts.

By that math, autos at 90 days of life require far more light on a daily basis than photo's on a 120 day lifespan would require, if your goal was to give both the auto and the photo the same amount of light over it's lifetime.

Now that's just Gee Theory, but autos at 1150PPFD vs photo's at 950PPFD get about 15% more light on a daily basis and live 25% less, so it gets pretty close.

Auto's still use more on a daily basis but they get 18 hour days so if you break it down into 90 days at 18 hours light for autos, vs 28 days at 16 hours, 28 days at 18 hours, and 70 days at 12 hours for photo's, photos get 10% more light if PPFD is the same, so if you up autos 10% in light intensity then it works out to the same over each plants lifetime.

So 1000 PPFD on a photo really is equal to 1100PPFD on an auto. Give or take a bit, but in general it makes sense that autos can handle more light.

Then toss in different tolerances for different strains and 1150 PPFD makes total acceptable sense.

The real question is did Gee Theory make sense?