VPD Hmmm: Observation

[Koolbudz]

Well inside I 'try' to keep my VPD optimum, but was wondering about outside and VPD.

I grabbed my IR Thermometer, tested the biggest fatest leaf and it was at 115F (90F - 36%RH by weather app)!!! that was in direct sun and towars the bottom of plant, the smaller leaves up top were only 105ish, this was across my whole garden, the larger leaves were way hotter by 10-20 degrees....

Now I have been instructed to test the tops to determine my VPD (indoors), but what about this I just witnessed? I have never tested the lower bigger leaves...

This makes me think, maybe we should test the larger leaves which are closer to the top rather then only the top most leaves to help determine VPD, so maybe hit the bigger leaves up 'near' top, calculate their average then test the smaller leaves, calculate their avereage temp then average those two temps and use that?

Is that what should be done or for those who keep a close eye on this and dont rely only on fully automated controls (expensive stuff), what was/is your process for reading temps to calculate VPD?

 

[TysonOG]

I use an IR thermometer for my indoor garden and my leaves always test 3-5 degrees below ambient.

 

[Jackalope]

Always weird hearing something totally new for growing. So much new stuff out there they say you can't live with out.

I don't have a clue what VPD is let alone test for it. The fact I have did fine up to now tells me it doesn't matter. At least to me and how I do things. For me simplicity is always best.

For every action there is a reaction. I feel if you are monitoring and changing things for one monitor. It might change other things in your grow that will be caught by another monitor. I know hydro guys need to track water real well. Temps are important too. Testing the plants reaction to the light seems a bit much.

Might be why I only used HPS lights for years. I knew they worked and didn't need to test how much light the plant was getting. I know what kind of penetration I can get with them. New COB led's are a lot different. The ones I use were highly recommended so there is no need to test the light any more then I have. Plants grow under them real well.

So tell me. What the hell is VPD? LMAO.

 

[Rosti]

Vapor Pressure Defecit, it is a way of ensuring you’ve dialed in your temp to RH ratio.. its also nice to dial in exactly how much air flow or AC you need to cool your room by converting watts to BTU. I like you did great without it, but did even better when I started utilizing it. There’s a science behind it so it definitely works, and is worth looking into.

 

[Bush Doctor 77]

As cannabis is a weed, and very hardy, it has other VPD needs than leaf lettuce. The VPD charts I've seen have all been universal for plants and not specific for cannabis. Today it will reach 100F in my greenhouse, 20% humidity, and my plants will grow 3 inches. They normally exceed 8 feet at harvest with 3 inch diameter stems.

 

[Jackalope]

Ah SCIENCE! that explains it all LMAO.

For me plants grow or they don't grow. I create a grow environment with out checking VPD by knowing what plants won't grow in. Same thing in a different way. Like you mentioned, you are using science to help.

One question won't the VPD change strain to strain?

 

[Rosti]

I use a cannabis VPD chart, not hard to find.. simple google search will reveal cannabis’s optimal VPD range charts. I’m talking about making an indoor grow dialed in, I never said you can’t grow weed without this chart lol I just said that my plants grow better now then they did before I started monitoring this. Lol Yes it will change slightly based on genetics, because obviously sativas enjoy a hotter environment then indicas, so when growing sativas you will have a hotter room, in return a different optimal VPD range. I’m confused why you say “science” sarcastically? This isn’t bro science, these are facts backed by studies. Lol Do a little research, or dont, it’s up to you. I like you, understood the basics like plants like 60-70% RH in veg and and 45-55% in flower and don’t go over this temp, etc, etc.. I grew amazing plants without ever checking anything I’ve mentioned, the only difference I’ve noticed by monitoring these things is the speed in which my plants grow, quality doesn’t change. Which if I can get to harvest faster I’m all for it, it’s not like some math equation. You monitor your environment and further dial it in using a cannabis VPD chart. Simple stuff and it works.

 

[Bush Doctor 77]

I use a cannabis VPD chart, not hard to find.. simple google search will reveal cannabis’s optimal VPD range charts. I’m talking about making an indoor grow dialed in, I never said you can’t grow weed without this chart lol I just said that my plants grow better now then they did before I started monitoring this. Lol Yes it will change slightly based on genetics, because obviously sativas enjoy a hotter environment then indicas, so when growing sativas you will have a hotter room, in return a different optimal VPD range. I’m confused why you say “science” sarcastically? This isn’t bro science, these are facts backed by studies. Lol Do a little research, or dont, it’s up to you. I like you, understood the basics like plants like 60-70% RH in veg and and 45-55% in flower and don’t go over this temp, etc, etc.. I grew amazing plants without ever checking anything I’ve mentioned, the only difference I’ve noticed by monitoring these things is the speed in which my plants grow, quality doesn’t change. Which if I can get to harvest faster I’m all for it, it’s not like some math equation. You monitor your environment and further dial it in using a cannabis VPD chart. Simple stuff and it works.

I didn't say there weren't charts, I just never saw one. I don't need to find one because I can't change mother nature. Maybe I'm taking it wrong, but you seem to be laughing at people a lot, and you also seem to find sarcasm where there isn't any. BTW, facts backed up by studies defines science!

 

[Rosti]

I didn't say there weren't charts, I just never saw one. I don't need to find one because I can't change mother nature. Maybe I'm taking it wrong, but you seem to be laughing at people a lot, and you also seem to find sarcasm where there isn't any. BTW, facts backed up by studies defines science!

Ya I think you definitely read my post in the wrong tone friend. I’m not laughing at you, Or anyone ... and I’m confused about finding sarcasm where this isn’t any? I wasn’t talking about you, I was referring to jackalopes comment on “AH science! ... that explains it all. LMAO” ... That was a very sarcastic remark. Also Im confused about your comment about facts being backed up by studies defining science? ... did you read my post? I literally said optimal VPD ranges facts backed by studies, not bro science... sorry man but it seems like your fishing for an argument and your looking in the wrong place for one. I was trying to hand out some knowledge to someone who asked. That’s all. I didn’t mean to offend you or seem sarcastic AT ALL.

 

[Rosti]

I didn't say there weren't charts, I just never saw one. I don't need to find one because I can't change mother nature. Maybe I'm taking it wrong, but you seem to be laughing at people a lot, and you also seem to find sarcasm where there isn't any. BTW, facts backed up by studies defines science!

I also never accused you of saying there weren’t cannabis VPD charts? I simply stated how to find one, no where did I say bush doctor doesn’t believe in cannabis VPD charts or anything like that. Lol Trust me my man, you took it the wrong way. But again although it was completely unintentional, I apologize for offending you... I’ll also work on the use of my “laughing” so as not to send the wrong message to people.

 

[Bush Doctor 77]

Ya I think you definitely read my post in the wrong tone friend. I’m not laughing at you, Or anyone ... and I’m confused about finding sarcasm where this isn’t any? I wasn’t talking about you, I was referring to jackalopes comment on “AH science! ... that explains it all. LMAO” ... That was a very sarcastic remark. Also Im confused about your comment about facts being backed up by studies defining science? ... did you read my post? I literally said optimal VPD ranges facts backed by studies, not bro science... sorry man but it seems like your fishing for an argument and your looking in the wrong place for one. I was trying to hand out some knowledge to someone who asked. That’s all. I didn’t mean to offend you or seem sarcastic AT ALL.

No sweat man. Sorry I read you wrong.

 

[Rosti]

No sweat man. Sorry I read you wrong.

It’s all good! You just helped me realize that maybe I should focus a little more on proof reading to make sure I don’t come off as a dick.

 

[Bush Doctor 77]

It’s all good! You just helped me realize that maybe I should focus a little more on proof reading to make sure I don’t come off as a dick.

The LOL's I took literally, and pictured the laughing--read it all wrong. Thank you impersonal internet!!!

 

[Rosti]

Fuckin Internet huh? ..no I assure you I’m not laughing at anyone, I was genuinely trying to answer jacks question. I’ll work on my typing skills, no harm no foul Doc.

 

[Jackalope]

YES I meant that as sarcasm.

Growing for me is a natural thing. I am not going to do it with meters and charts. If you start telling me I need them. I am going to break out my Science jokes. And yes to me this is another useless thing some smart person figured out while growing. Dirt, seed, light, and food is as far as I go.

 

[Rosti]

Is your natural grow done indoors?... do you not use a hygrometer? It really is as simple as looking at your temperature and adjusting the RH to the zone for better plant respiration or “faster growth”... no one is telling you to go buy a laser thermometer and a chalk board to play scientist with. Lol BUT I can see you really had no intention of learning AT ALL when you asked that question... more akin to a troll fishing for responses he doesn’t care about.

 

[Jackalope]

Now who seems to be getting upset? How do you know what I a willing to learn? I have found a few things I thought were ridiculous at first and do them now. Look back I am one of the guys that said I would never use a LED light. I am not sure what a hygrometer even is lol. Not saying I won't buy one. I like new toys for growing.

Humidity is a double edge sword in ways. To much and you will have problems. To little and plants don't grow well. Low humidity here, so I will never have a high humidity problem unless I try to manipulate the humidity. Something I choose not to do. I can keep mine in the 50% RH range

Which brings me back to a question that has not been answered. So many strains grow different. Wouldn't a leathery thick leaved indica want something different than a soft thin leafed sativa? I grow 4 to 5 strains at once in the same tent. If I change things for one plant. Would that put a different strain in a bad environment?

 

[Rosti]

Now who seems to be getting upset?
I’m not upset at all my man, I’m sorry if me calling you a troll offends you but I call it as I see it. It’s counter intuitive for everyone for you to even ask a question you don’t care about. It wastes my time, and stirs up needless drama.
How do you know what I a willing to learn? I am not sure what a hygrometer even is lol.
Again the sarcastic remarks and your response “Growing for me is a natural thing. I am not going to do it with meters and charts. If you start telling me I need them. I am going to break out my Science jokes. And yes to me this is another useless thing some smart person figured out while growing. Dirt, seed, light, and food is as far as I go.” ... That statement tells me exactly how much your willing to learn.

Which brings me back to a question that has not been answered. So many strains grow different. Wouldn't a leathery thick leaved indica want something different than a soft thin leafed sativa? I grow 4 to 5 strains at once in the same tent. If I change things for one plant. Would that put a different strain in a bad environment?

I’m fairly confident you didn’t read my response above... I will be redundant and repeat myself. Sativas usually enjoy a hotter environment, while Indicas tend to prefer a cooler climate. Genetics also play the biggest role, it’s not just sativas and indicas... there are Indica strains that grow better in hotter climates and vis a versa with sativas... so more then aanything it comes down to the genetics your growing and the climate those strains prefer. Now let’s say your growing a group of strains that will thrive in a hotter environment, those plants will have a different optimal VPD then say a group of plants that are grown in a room with a cooler climate. So short answer is yes, different strains will have different optimal VPD’s. So example... if you had 4 Sativas in a tent that want a polar or tropical climate, with 1 Indica that would prefer a more temperate and cooler environment, and you catered the VPD to the Sativas the Indica would not grow with the same speed and vigor.. it will still grow into a great plant, but the sativas will grow much faster due to them having the optimal environment for plant respiration.

A hygrometer is just 2 in 1 device that reads your grow room temperature and humidity.. it’s just a thermometer and a humidity monitor built into one. Very useful. Hopefully I answered your questions jack, take care.

EDIT: Again I would like to point out to you that I’m not trying to tell you that you need to do this to grow great weed, I myself, even explained earlier that I grew great buds without monitoring my plants to the extreme. I’m simply just answering your question, not trying to force this method on you or make it seem superior to any other grow style in any way.

 

[Jackalope]

Troll? I have seen trolling and didn't think it was anything like what I was doing. Maybe I didn't ask questions right or the way you liked. I really wasn't trolling you.

Best way to find out if you want to try something new is to understand it. Yes I was trying to poke holes in your theory. I want to make sure I am not going to run into problems before I try anything new with my plants. Like you mentioned you don't have to do it, it just makes things better. I do lots of stuff to get my plants a little bit better. It may not be your way to understand stuff but it is mine. So many new things in growing. Most are useless. Some may really work. I like to see any faults way before I try anything.

I guess I do know what a Hygrometer is. I just didn't know the name. I use a multi station weather unit that covers humidity temp in all my tents on one display. I always know what my temp and humidity are I just don't try to adjust it. Mostly because of the strain thing. I have sativa's indica's and hybrids in each grow. There is literally no way for me to decide which plants I want to make happy. With 2 or 3 plants of each strain there is no dominate strain to key in on. So this idea will not work for me.

I am not sure what you got out of this conversation. I got the answers I needed. Sorry if you didn't like how I got to here. You are right. I must have missed the first time you mentioning about different strains. I needed to know if this idea would work with multiple strains at once.

 

[Rosti]

Troll? I have seen trolling and didn't think it was anything like what I was doing. Maybe I didn't ask questions right or the way you liked. I really wasn't trolling you.

Best way to find out if you want to try something new is to understand it. Yes I was trying to poke holes in your theory. I want to make sure I am not going to run into problems before I try anything new with my plants. Like you mentioned you don't have to do it, it just makes things better. I do lots of stuff to get my plants a little bit better. It may not be your way to understand stuff but it is mine. So many new things in growing. Most are useless. Some may really work. I like to see any faults way before I try anything.

I guess I do know what a Hygrometer is. I just didn't know the name. I use a multi station weather unit that covers humidity temp in all my tents on one display. I always know what my temp and humidity are I just don't try to adjust it. Mostly because of the strain thing. I have sativa's indica's and hybrids in each grow. There is literally no way for me to decide which plants I want to make happy. With 2 or 3 plants of each strain there is no dominate strain to key in on. So this idea will not work for me.

I am not sure what you got out of this conversation. I got the answers I needed. Sorry if you didn't like how I got to here. You are right. I must have missed the first time you mentioning about different strains. I needed to know if this idea would work with multiple strains at once.

Your fine, I was just trying to help you. It’s not my theory though, these are facts backed by studies done by universities. Theories are untested hypothesis, just want to clear that up. But actually it will work with multiple strains, even if you mix Indica, sativa, or hybrid... it’s more about the genetics, it just means you have to plan your grows accordingly by planting compatible genetics. My next grow will feature landrace sativas, hybrids, and pure indicas... they will all grow with the same optimal VPD because of their genetic lineage and make up.