Ruwtz Maneuver Vol 1

ruwtz said:

Based on the assumption that plants prefer higher humidity at warmer temps, and presuming I want to stay at 78F daytime, perhaps I should bring humidity up to 60% or more? I think in their struggle to stay hydrated in 55%RH the plants are wasting energy in drinking heavily, and possibly leading to slight toxicity.

This is a function of vapor pressure deficit on plants, right?

Presumably the reverse could also apply: reduce the daytime temp and maintain current 55%RH. Temps are up precisely to keep the girls drinking but if its going to make them even more sensitive to feeding than they already are then i'm not going to push them.

Where do you guys keep your veg RH for optimal plant metabolism?

Click to expand...

I would say that since you were able to get the roots out and growing.....that you can now dial in the enviroment per VPD if you want....
also.....I believe that plants do take differ nutrients....however not that much that it will make that dramatic of a difference
also I would just start flooding.....
so manually flood for 15 min and drain
see how long it takes to dry
then set a timer for that many days or hours or whatever....then periodically check
if they are drying out faster....shorten the time between feedings to reflect the drying time
once you get your plants into a routine...I find they live much better
they stop worrying about all the stresses and anxieties and focus on growing
just my 2 pennies worth

Dehu has been set to 70% and I will be recording temps & humidity throughout the day for the room and the canopy, and as best I can for leaf temps although I know that is difficult.

This is up from 55% which may or may not have been causing some VPD effects / looking like tox or def.

As I understand it people aim for a VPD of between 8.0 and 10.0 and I have several charts to reference the sweet spot. I am aiming for 75F at 65-70% humidity as my room seems able to manage this temp very well even on very hot days outside.

I still don't know how to establish a decent 10 degree drop for night times since these cobs kick out hardly any heat that would otherwise contribute to a decrease at lights off. I did trial the AC timer to turn off with the lights but since this room is 90% sealed this didn't really do much: temps just held in the mid to high 70's. I'd rather condition the air and keep that number stable, so AC continues to run 24/7.

RO filter is running and I should have a full res in a day or so, so we will see where the girls are at before going to flood. I do not want to repeat the overwatering and most of the blocks remain heavy from this weeks' watering. I'm going to aim for 650ppm. Hopefully my temp/humidity combo hits the right VPD to encourage the girls to feed as they should be. All are over a month old now so we really ought to be rocking.

@Wisher2 Since pH is so stable in RO, do you then fully articulate the res pH in order to facilitate the whole range of uptake? eg. starting at 5.5 and going to 5.6 for the next water and so on up to 6.0?

Also, do you guys pH before nutes then again after? In soil with tap I found this used much less pH down and at least appeared to hold a little better, but not sure if this will apply to hydro/RO. I have heard pH'ing plain RO doesn't work because there is nothing in it to buffer. Thoughts?

I'd keep RH in the fifties for veg. A lil co2, not much. As soon as they have roots, give them all the light they can take, cuz that's what makes them grow.

ttystikk said:

I'd keep RH in the fifties for veg. A lil co2, not much. As soon as they have roots, give them all the light they can take, cuz that's what makes them grow.

Click to expand...

Hmm, that is interesting. Whats your temps? Do you AC? And is VPD important to you?

From early tests today I have the following:

[1] Leaf temp *recorded as best I can manage*: 72F, which at 100%RH is a vapor pressure of 26.4
[2] Canopy = 74F/67%, and charts say 10.4 (vp or milibars?)

Subtracting one from the other gives me 16, which is way out of the 8-10 range. I have some manipulating to do. Either that or there's a limit to how much credence I can give to the leaf temp measurement - I basically just have a therm shoved in under a good growing branch.

ruwtz said:

Hmm, that is interesting. Whats your temps? Do you AC? And is VPD important to you?

Click to expand...

Temps mid to upper 70s, I run water chilling but it dehueys as well, and yes VPD is very important to me- to the point where I've gone a few rounds with fools here thinking that 20% RH is going to get them bumper crops lol

The numbers I gave you are for veg. Lots of light is a key.

ruwtz said:

From early tests today I have the following:

[1] Leaf temp *recorded as best I can manage*: 72F, which at 100%RH is a vapor pressure of 26.4
[2] Canopy = 74F/67%, and charts say 10.4 (vp or milibars?)

Subtracting one from the other gives me 16, which is way out of the 8-10 range. I have some manipulating to do. Either that or there's a limit to how much credence I can give to the leaf temp measurement - I basically just have a therm shoved in under a good growing branch.

Click to expand...

Laser temp sensor is best, but I don't believe you're at the stage where tweaking VPD is going to make much difference as yet.

Ok, thanks, I just wanted to rule out VPD as causing minor signs of tox and def at the same time (dark top fan leaves here, pale leaves there, tip curling.

I'm on a mission to refine everything of course but I will be satisfied if my temps and humidity are in harmony sufficient for good growth. I should be further along than I am but its taking time to get this room right and its a lot of firsts all at once.

And yes, we are still in veg here.

I've wanted a laser temp sensor for ages so i'm stoked you've given me an excuse to buy one.

Oh and light: I have x8 3590's @1.4a 5000k spectrum over a 3x7ft table, at 12-18" above canopy, and I think the girls are happy for it.

ruwtz said:

Ok, thanks, I just wanted to rule out VPD as causing minor signs of tox and def at the same time (dark top fan leaves here, pale leaves there, tip curling.

I'm on a mission to refine everything of course but I will be satisfied if my temps and humidity are in harmony sufficient for good growth. I should be further along than I am but its taking time to get this room right and its a lot of firsts all at once.

And yes, we are still in veg here.

I've wanted a laser temp sensor for ages so i'm stoked you've given me an excuse to buy one.

Oh and light: I have x8 3590's @1.4a 5000k spectrum over a 3x7ft table, at 12-18" above canopy, and I think the girls are happy for it.

Click to expand...

I run twice that much light as that, so feel free to bunch things up a bit.

ttystikk said:

I run twice that much light as that, so feel free to bunch things up a bit.

Click to expand...

Presumably you are running separate veg and flower rooms?

After research and recommendations I got this cob setup to fit this space. Do you think i'm underpowered?

ruwtz said:

Presumably you are running separate veg and flower rooms?

After research and recommendations I got this cob setup to fit this space. Do you think i'm underpowered?

Click to expand...

I can't tell without looking at the setup in detail, I'm better in person.

Do you have a fan blowing across the plants? Not enough to bend them, just to ruffle the leaves?

ttystikk said:

I can't tell without looking at the setup in detail, I'm better in person.

Do you have a fan blowing across the plants? Not enough to bend them, just to ruffle the leaves?

Click to expand...

Yep, plenty of ruffling!

Also on the 24 Carat (Tangie x Kosher) we have some sexual maturity going on... three girls at day 54 from seed. Again they should be further along but with all my setup issues and setbacks this really was the guinea pig strain. I'm delighted they are even still with us.

I wasn't planning on vegging this long but we're playing catchup here, so its interesting/unexpected to see this development.

Presumably the time sexual maturity shows in veg is strain dependent? Its not something I would ever think about outdoors: I just timed to the seasonal calendar. I see that it could also be helped along by light spectrum: Rosenthal claims blue light can encourage pre flowering in veg? I'm running 5000k cobs so it could be complimenting the natural passage of time.

ttystikk said:

Temps mid to upper 70s, I run water chilling but it dehueys as well, and yes VPD is very important to me- to the point where I've gone a few rounds with fools here thinking that 20% RH is going to get them bumper crops lol

The numbers I gave you are for veg. Lots of light is a key.

Click to expand...

Ok so i'm too curious not to ask... you're running mid to upper 70F's whilst humidity is in the 50's. This is where I was at when the plants were in sick bay and then into recovery some leaves were starting to look crispy so I figured it was too hot and too dry. This is where I started to consider VPD.

With these settings, how do you get to the VPD sweet spot that all the charts demonstrate? I know you're telling me not to worry, and i'm not, but... I MUST KNOW THESE THINGS

just to give you an idea....these are now about 12 days from seed

this is what the enviro looks like
and my plants are sitting in a basin of nutrient solution....all flood no drain

ruwtz said:

Ok so i'm too curious not to ask... you're running mid to upper 70F's whilst humidity is in the 50's. This is where I was at when the plants were in sick bay and then into recovery some leaves were starting to look crispy so I figured it was too hot and too dry. This is where I started to consider VPD.

With these settings, how do you get to the VPD sweet spot that all the charts demonstrate? I know you're telling me not to worry, and i'm not, but... I MUST KNOW THESE THINGS

Click to expand...

the crispyness of the leaves.....there could be a possibility of to much wind from the fans blowing to close......
to me the plants that have that droopy look have 1 of 2 things......under or over watering
once the roots show....IMO there is no such thing as over watering
as those roots can now sit in water....as long as oxygen remains in the solution....the roots will grow
with enough light the vegetation will grow
I like to over simplify things.....it has gotten me by so far

Wisher2 said:

just to give you an idea....these are now about 12 days from seed
View attachment 3779109 View attachment 3779110 View attachment 3779112
this is what the enviro looks like
and my plants are sitting in a basin of nutrient solution....all flood no drain

Click to expand...

It certainly gives me an idea of your setup and what works for you.

Wisher2 said:

the crispyness of the leaves.....there could be a possibility of to much wind from the fans blowing to close......
to me the plants that have that droopy look have 1 of 2 things......under or over watering
once the roots show....IMO there is no such thing as over watering
as those roots can now sit in water....as long as oxygen remains in the solution....the roots will grow
with enough light the vegetation will grow
I like to over simplify things.....it has gotten me by so far

Click to expand...

Yes, too windy really could be it. My oscillating fans are close to the table. For now I have faced them to the wall so the flow is indirect and still getting a decent flutter, but I will be moving the fans higher up the wall tomorrow.

Sometimes its the simplest thing that evades me.

Also I took your advice and did the first flood today since the RO filter was fitted as some were very light. Fed at pH5.7, 710ppm / 1.0EC, straight up Flora Trio, CalMag and Hydroguard for 15 mins. They look perky but I will give it a day or so to see how they drink / dry before deciding on a timetable. Ideally I want to run this once a day at lights on but we will have to see. I think your claims about roots is good common sense so I don't think i'm too far off getting this right.

Still want to know more about refining VPD though...

Right now it seems the closer I push my temps and humidity similar to @Wisher2 and @ttystikk the higher my VPD value as per the charts goes up and away from the sweet spot. I could be calculating wrong, though. Is this correct?

1.Measure the leaf temperature and look up the vapor pressure at 100% RH

2.Measure the air temperature and relative humidity and look up the nearest vapor pressure figure

3.Subtract the air vapor pressure from the leaf vapor pressure

Example:

Leaf Temperature = 24°C (100% RH) Leaf VP: 29.8

Air Temperature = 25°C @ 60% RH Air VP: 19.0

VPD= 10.8

**VPD 8.0-10.0 ideal**

C'mon, humor me here. I'm on one.

ruwtz said:

It certainly gives me an idea of your setup and what works for you.



Yes, too windy really could be it. My oscillating fans are close to the table. For now I have faced them to the wall so the flow is indirect and still getting a decent flutter, but I will be moving the fans higher up the wall tomorrow.

Sometimes its the simplest thing that evades me.

Also I took your advice and did the first flood today since the RO filter was fitted as some were very light. Fed at pH5.7, 710ppm / 1.0EC, straight up Flora Trio, CalMag and Hydroguard for 15 mins. They look perky but I will give it a day or so to see how they drink / dry before deciding on a timetable. Ideally I want to run this once a day at lights on but we will have to see. I think your claims about roots is good common sense so I don't think i'm too far off getting this right.

Still want to know more about refining VPD though...

Right now it seems the closer I push my temps and humidity similar to @Wisher2 and @ttystikk the higher my VPD value as per the charts goes up and away from the sweet spot. I could be calculating wrong, though. Is this correct?

1.Measure the leaf temperature and look up the vapor pressure at 100% RH

2.Measure the air temperature and relative humidity and look up the nearest vapor pressure figure

3.Subtract the air vapor pressure from the leaf vapor pressure

Example:

Leaf Temperature = 24°C (100% RH) Leaf VP: 29.8

Air Temperature = 25°C @ 60% RH Air VP: 19.0

VPD= 10.8

**VPD 8.0-10.0 ideal**

C'mon, humor me here. I'm on one.

Click to expand...

well the problem with VPD to me is......and I believe many can back me on this
there is no real way to take temp of the leaf
the interior and exterior can be different.

even with an ir gun....it isnt 100% accurate

I take a different approach to VPD

I watch the leaves....when they are praying...they are in optimal growth stage...you can keep it there
by keeping the correct moisture level at the roots...for them to transpire....the lower the RH the more you water the higher the rh ....you get the picture
to me VPD really dosnt mean much
I know about it but have never followed the program and have always had excelent results....I have checked my VPD and have always been completely out of range....like really bad

I grow alot of Afghan strains
I keep it a little dry
Veg RH 55-65 Temp 75-80
Flower RH 35-60 Temp 75-82
havnt let me down yet

I just match the watering with the RH

Higher RH = less frequent watering higher EC
Lower RH = more freq watering lower ec

I stay in the green;

ttystikk said:

I stay in the green;

View attachment 3779273

Click to expand...

Ok, makes sense and I have been using that chart. The axes make easy sense if you want to stay in the green: ie. choose a temp and choose its correlating RH, however the corresponding values don't make sense with the way i'm calculating (my workings are above). It seems the more I improve the relationship between temp and RH (going by this chart), the more my VPD measurement goes way off, and perhaps @Wisher2 is explaining the same issue.

@ttystikk how are you in the green if you're mid 70's temps and in the 50's for humidity? Going by the chart alone, 50's humidity puts you in low to mid 60's for temp, which can't be right. Am I reading this wrong? Are their other factors i'm just not considering?

I'm not going to get bogged down in numbers and this is merely a curiosity to me, but it is bothering my brainbox, and i'd like to work towards fully realizing this if i'm going to be a competent grower like you lot.