Ina
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O,really:)Humidifiers are very cheap and easy to run to increase RH.
O,really:)Humidifiers are very cheap and easy to run to increase RH.
I can see what you’re sayingYou'll find that trying to work in VPD optimums offers growth and plant health benefits. 40% RH is way too low unless you are in late flower and trying to prevent fungal pathogens. I hope I have clarified though that I'm a big fan of VPD. Its more a case that some growers misunderstand it a bit. The main thing really for less experienced growers to understand is that if you use the VPD chart it gives you a very good picture of where your RH should be relative to temp.
Ah no I haven’t done that my leaves are probably cooler than air. I got my rh to 40-45 now but just because I dropped temps like 4 degrees.Have you measured leaf surface temperature in this equation? Understanding the leaf surface and air temperature differential is important in VPD. This is what I mean by it being more complex than many growers think because there are numerous variables that need to be factored into the equation.
Ah no I haven’t done that my leaves are probably cooler than air. I got my rh to 40-45 now but just because I dropped temps like 4 degrees.
Idk I’m just trying to figure why my plants (which I’ve run clones from same mother same lights n all. ) are uptaking 3x as much as ever before but not burning. Actually demanding more. And that link told me why
See we are talking complex and I think we’re talking misunderstood simply because everyone wants to quote some text bookYeah its one misconception I've encountered recently when an advanced level grower came to me for consultancy and started ranting on about low EC and an aggressive VPD. I was what are you talking about man? Optimum EC really comes down to nutrient status and fertigation frequency with environmental factors such as RH and temp playing a much much lesser role. In fact studies show that certain nutrients such as iron are uptaken and found at higher levels in the plant tissue at high RH while other nutrients will be uptaken and present in the tissue at lower RH. So basically we are talking extremely complex biochemistry and plant physiology that a lot of growers might understand some of but miss other key parts of in understanding (resulting in incorrect assumptions).
I have a buddy that gets consistent good results by doing just about everything "outside the box", only because he's never read a book or done any research, I swear to god some people are just lucky. I'm on the other end of the spectrum, constantly researching and experimenting. I like to wick as much wisdom as I can from the scientific types with their research and the outlaw OG types with their years of hands on trial and error, thus I'm perpetually changing 6 things at a time, never knowing for sure what's what.:)See we are talking complex and I think we’re talking misunderstood simply because everyone wants to quote some text book
Complex because of people making it that way.
Prime example look at math in school now. 20 steps in a circle to get the same answer we used to get in 2 steps when I was in school.
Now vpd and what I’m getting to.
I’m not gonna write a book unless someone really wants the rest of my theory. Maybe I’ll put it on my diary thread if someone wants to see it and exactly why I’m saying it. In action.
But main point vpd chart means nothing. It does give you an idea of where your highest transpiration rates are so in that form useful otherwise useless.
This is where it falls apart
Where everyone keeps digging too hard into an unproven science based on a book written by someone probably never grew a weed plant.
Facts in basic terms
We have a plant it wants to grow. It’s alive
living things need water period
If our air is stripped of water the plant is forced to hydrate itself other ways ( roots)
This causes more rapid uptake. More Rapid transpiration.
Also causes nutrients to be moved and used more rapidly.
Low rh starts showing with yellowing right? And crispy leaves Why is that? Yellow hm
Yellow = lack of or lock out of nutrients period. No other thing causes yellow. Whether ph is off or whatever
the lack of available nutrients to be uptaken is where the final fade and any stage plant yellowing comes from.
Now when rh is low
back to common sense
you are forcing the plant to draw from roots more. Leaching your nutes too. So you either end up yellow from demand of more inputs by the plant that done stripped your soil ( yeah that quick)
or crispy n burned n people calling it rh and windburn but it’s a flash nute burn in reality. Usually on less tolerant strains
From the rapid transpiration going on. From the low rh. There’s a lot more to it but my theory is based more on common sense. It’s as simple as people not thinking about cold contracts n hot expands.
But I think I’m in no hurry to try upping my rh. I’ll just stick to the full course meals regularly with tons of extra water to keep the yellow out n watch em explode.
I’ve never fed full strength. N saw burn at 75% before. On these same clones
Why the higher rh/ pressure you were talking about actually cuts transpiration slowing the flow building up.
With the low rh I’m throwing full strength with bloom booster calmag molasses all that every feed
Every day. And they suck it dry twice. In 4 gal pots. But now that I’m meeting thier crazy demands they are green again and I can see they been using the nutes like steroids
I think the chart is useful to an extent but I think you can go “ outside the box “ n actually get better results if you play it right.
This is all very interesting. For 30 years growers have done things one way pretty much like the old grow books advised.
Metal halide for blue in veg hps in flower for more red.
High humidity for clones, seedlings and young plants through veg. Lowering humodity for flower.
Now we have many more growers and businesses throwing their experience and research in the pool.
Why are the same debates still going on as decades ago about growing weed while every othwr kind of farmer has specific nute ratios and parameters to follow on any agriculture info?
Its because weed gets you high and thats when weed growers start thinking about their job. ;-)
That said. If you look into different cultivars like say roses or lettuce you will see that the grower uses different techniques, parameters and nute ratios for the different sort of crop.
Lettuce is to harvest leafy greens but roses only the stem and flowers. They need different light spectrum, envirenment and nutrients to give best potential.
Well we grow for flowers. But our plant grows a leafy structure in veg. So tech like vpd and full spectrum lighting with a good balance of blue will grow the best leafy compact plants.
But in flower we want a safer envirenment for mold so lower humidity. We want lower temps to preserve potency and flavor. And we want more red light to spur branching and flower set and bloom.
So there is no answer that makes any tool or technique automatically correct.
why are these discussions always one side or the other?
Our plant has multiple different stages and it aint lettuce. :)
This sounds right and again proves my point. That inside or outside if vpd range you can still get good results by altering the inputs. N not just nutes. Amount frequency all that like you said. It explains why I’m ok at 40% when like your own words said “every grower” going by the book will say I’m wrong. I’m saying they are all wrong. N my wall of bud proves it. Along with the small print in everything everyone is saying here. It’s like we agree yet disagree. How they say in the movie blow ? Chasing the wrong dream. That’s where it’s going wrongI think where nutrient strengths are concerned it comes down to 1) whether you are recycling or growing RTW/DTW. For recycling growers who purchase off the shelf formulas and don't lab analyse and correct for specific ions they need to run higher strengths (EC) so at that point luxury feeding is a must because there is a preferential removal of some nutrients over others and some nutrients become depleted in solution while others accumulate - so at that point running high strengths as per feed charts is perhaps necessary. But in RTW/DTW where fresh solution is fed at every feed most charts recommend too high ECs. 2) fertigation frequency inline to nutrient status is all important in determining optimum EC because higher numbers of fertigations per day will mean you can run a far lower EC than say 1 fertigation per day in RTW/DTW etc. So the point being when you talk about optimum EC you must factor in the growing methodology as key in the equation. Definitely though some nutrient manufacturers make insane recommendations with regards to EC (ml/gal ml/L) for a lot of growing methodologies.
Absolutely but also when people talk VPD this is also spoken about in many cases. That is, it is desirable to not run what is considered optimal VPD when considering other factors such as young veg plants (which want high RH) and developing flowers and mould (where you want to run very low RH of 40 - 45% RH). Also and one reason I say VPD is misunderstood by a lot of growers is that you need to consider why scientists look at VPD and this for the most part is to evaluate water status relative to stomatal conductance and growth rates. Most of these studies are also done in soil in either greenhouse or outdoor crops so firstly it is important to disseminate information from what were the scientists looking at and what were the parameters of the study?
In hydroponics we aren't nearly as concerned about water use and wilting points etc as are outdoor growers for instance. I think what happens too often is people misinterpret the data and don't stop to think yes but all good and well but what is the point of this in my situation? So it's important to step back a bit from research and evaluate what the parameters of the study were.
Just quickly though on the subject of MH and HPS - there's no doubt indoor lighting is on the change with better and improved lighting technologies which are developed for optimised crop growth beginning to emerge. So just because growers have done it for years doesn't make it the best way - more a case of it being what was available at the time. And that's the thing about science; it enables us to evolve and improve things.
Also mate, a lot of the old grow books aren't so good. By following their info you'd be losing yield when compared to growing using cutting edge technologies. The Med scene is like any other. It had to start somewhere. It's been evolving ever since.
I think one thing many growers miss is that a plant's genetic potential evolved under certain conditions. So for example cannabis evolved under the sun (not HPS or MH lighting) which provides a very broad spectrum at differing levels and ratios. It also evolved during the Mid-Palaeozoic era at high CO2 (1500–3000 ppm) before the beginning of a period of low CO2 (<1000 ppm) we are in today so if you want your crop to achieve genetic potential it is imperative to produce under light that is very similar if not identical to the sun re spectral output and under high CO2 (i.e. CO2 enrichment).
All I can say about LED is to date it has been very disappointing but its an evolving technology so perhaps one day they will get it right (perhaps not). However, if you want to achieve optimum yields give LED a miss for now.
Yes it should if the breeder nailed the parameters before breeding.Ok. This is an interesting point. However our indoor cultivars have been bred under hps for 40 years.
Will the highest potential maybe be with the breeders parameters?