Vpd And Running A Small Perpetual Harvest!

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Lazerus00

Lazerus00

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So as I kick off another grow cycle I think that its time I try a perpetual harvest. After looking at the VPD chart that is located below, and learning that the "ideal VPD" is between 8 and 10 or there abouts, I have some questions. I remember the first time I looked at this I thought, "im way off"! My RH was ALWAYS much lower at the temps I usually run, and from what I read, a lot of other peoples grows are the same. Let's say your lights on are between 75-80f which I feel is a safe average for most grow, well the chart says that your RH should be between 65-75%....Okay so even though it kinda of a bitch to maintain an RH that high, lets say I did, well arent plants going thru veg supposed to experience a drop in RH as they get closer to flower? I always thought if your RH was 65-75f at the start of veg, by the time your plants were about to switch to flower that the RH should be around 40%. Well if I am running a perpetual harvest and have plants vegging at all different ages, whats the proper RH?? Is there one set RH/Temp that will maximize the use/benefits of VPD and be okay for plants of all ages? I'm just worried that if I keep temps at 75-78f and follow the VPD chart keeping my RH between 65-75% that the girls that I flip into flower will not be happy jumping in the flower tent with an RH of 30-40%...Okay and thats another thing! Ive always read to not let your RH in flower get above 40%...Well then following the VPD chart, the ideal temps are between 55-60ish degrees?? Does ANYBODY keep their flower tent at between 55-65f?? Have I been doing this wrong all this time having my flower tent at between 70-80f?? Any thoughts, input, suggestions, or general discussion about THIS topic is welcome!!

Oh and not sure if its needed to help discussion but im currently vegging in a 4x4 1000w HID tent which is right next to my flower 5x5 2000w HID tent...
Vpd chart
 
greenthumb89

greenthumb89

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In regards to the perpetual im assuming your running one strain just find the best humidity level for that strain and go with that. At the end of the day its better to have a constant humidity rather having it drop and raise all over the place
 
Lazerus00

Lazerus00

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If only...Im deff running multiple strains and I feel it will be mixed strains for a while....Either way I feel like you advice stands. I should play with it a lil and try to find the best/happy RH for the lot of 'em!
 
S

SativaD82

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Hi So I have been running a perpetual cycle for some time and I have just started to look into Vpd. My veg is always a constant 78 f and Rh of 60. Our flower is set to 75f and we try to keep the Rh around 50. These are day time levels and we seems to be doing fine. I would love to run the humidity higher but too much risk of fungus and mold developing. We do notice that we have to feed more often due to the plant giving off more h20
 
Organikz

Organikz

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Hi So I have been running a perpetual cycle for some time and I have just started to look into Vpd. My veg is always a constant 78 f and Rh of 60. Our flower is set to 75f and we try to keep the Rh around 50. These are day time levels and we seems to be doing fine. I would love to run the humidity higher but too much risk of fungus and mold developing. We do notice that we have to feed more often due to the plant giving off more h20
Yes the plant respirates more. The stomata open up completely. This will make for a nice healthy plant. The tissue becomes impenetrable to fungus, mold, even insects. Keep good air circulation. I've flowered in 75% with no problem. The plants grow like crazy.
 
EventHorizan

EventHorizan

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Im with ^^^. I ran 75* and 65% rh the whole grow. Start to finish. Just make sure u got decent airt movement, and keep it maintained. Its the spiking that causes you problems. The science is in the pressure that the atmosphere puts on the stomata, called atmospheric pressure. My problem now comes that im adding c02 this round and that means 82* which puts my rh at like 75%. My carbon filter will not work very well at 75% rh, and Im scared that im gonna lose smell out my window Ac Unit. Im gonna run that rh at 75% untill I notice any smell outside the window unit then I will drop it to 65% the rest of the way. As for lower rh in flower as the norm, they also drop the temps, which changes the vpd.
 
EventHorizan

EventHorizan

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I just set my dehuey to 50%, over 60=budrot, under 40=wilted veg growth and twisted leaves
if you get bud rot, then you are not employing good grow room practices, are you got a shady pheno that has very little resistance to pathogens. I would cull and replace with something worthy of being in that spot. My urkle crosses loved the higher rh, vpd... I will never change back.. All the lies about higher rh that I have read online.. no wonder ppl are scared.
 
DrMcSkunkins

DrMcSkunkins

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I had budrot last run and I have more fans than I should need. My temp and humidity got up above 80F and 65% a few days when it wasnt warm enough outside to kick on the AC. If you have the mold spores in your air and your rh gets over 65 a few times you get bud rot, had it twice.
 
EventHorizan

EventHorizan

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I had budrot last run and I have more fans than I should need. My temp and humidity got up above 80F and 65% a few days when it wasnt warm enough outside to kick on the AC. If you have the mold spores in your air and your rh gets over 65 a few times you get bud rot, had it twice.
Wrong.. That is fake news.. The reason you had bud rot was due to it spiking, and the high temps AND high rh.. See you just said what your problem was. You aint dialed in. My ac is on when ever auto pilot says, along with dehuey, huey, c02... No spikes, no oops it got hotter than I thought. If someone is set up or dialed in, vpd and higher rh IS THE WAY to go! If not, well your looking for problems anyway...
 
DrMcSkunkins

DrMcSkunkins

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Wrong.. That is fake news.. The reason you had bud rot was due to it spiking, and the high temps AND high rh.. See you just said what your problem was. You aint dialed in. My ac is on when ever auto pilot says, along with dehuey, huey, c02... No spikes, no oops it got hotter than I thought. If someone is set up or dialed in, vpd and higher rh IS THE WAY to go! If not, well your looking for problems anyway...
So your sayinh bud rot isnt a mold, isnt caused by spores that may or may not be present and having a high rh in flower wont get your buds grey and fuzzy?
 
EventHorizan

EventHorizan

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So your sayinh bud rot isnt a mold, isnt caused by spores that may or may not be present and having a high rh in flower wont get your buds grey and fuzzy?
Im not saying anything about spores not being present. Im saying that high rh is not the sole reason for bud rod, or pm. Im saying that running higher rh is BENEFICIAL to good growth, AND, is safe as long as certain principals are being followed. And he asked about vpd specifically. Saying dont go above 60 % will cause bud rot IS JUST NOT TRUE! I just did it! And its was my best smoke and poss the best smoke I have ever had. I guarantee its top 3... And I contribute that a lot to the vpd, and my laid back low ec i ran...
 
Lazerus00

Lazerus00

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Woah woah woah! Things kicked off in here while I was doing some of my sleepz! Lots to respond to!! So leaving aside the above disagreement about budrot bc I am also in the belief that high RH grows are possible with good, consistent, and clean growing practices. So about a higher RH in flower. I can understand why you might want a higher RH in the beginning of flower but don't really understand wanting it for the 2nd half of flower. I have always had the belief that a lower RH has been shown to increase the plants drive to produce trichomes and be that greasy jewel we all want in our garden, at least thats what I have experienced. The higher RH in the beginning deff helps your plant grow to the fullest of its potential, especially when correctly supplementing co2. But what are your reasons of wanting such a high RH (anywhere near 60% and above) for final bud development? What benefits have you seen for your plants in late flower? I hope in no way this comes across as anything but inquisitive, I'm just curious to hear about the subject!
 
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Organikz

Organikz

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I agree with both points honestly. If your plants SAR is high which a plant respirating and processing at full capacity should have, the brix should be so high that mold or mildew can't even attach to the tissue.

However sometimes our plants do see some weak moments and this is why a lot of people avoid high humidity. This is when the mold and bugs get in.

Many things along with cannabis thrive in high humidity. Just ask my broad mites. They loved it last run. I don't think they'll be returning from their neem showers.

This is a risky move but I personally had no issue with mold and the plants vigor doubles. Would I advise it and tell you 100% you won't get mold...nah. gotta keep them plants happy and healthy to avoid the mold.

I like old leadsled. He gave me a great quote.

"Pests are nature's garbage collectors and disease is the clean up crew."

I won't argue one way or another.
@DrMcSkunkins is just playing it safe which I totally understand. To some the risk outweighs the benefit to others the benefit outweighs the risk.

Josh steensland pointed out that his plants produce more co2 than his tanks are set to at night when running 75% during flower.
 
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Organikz

Organikz

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I would like to add what drives trichomes production is proper assimilation of sugars that deliver calcium and silica to your flower. Trichomes are mostly made up of silica and carbon. However as you implied it is believed environmental stresses do factor into signals to activate enzymes. I don't think there is a true understanding yet but I could be wrong. Trichomes are believed to be a defense against pests, uv light, and extreme temps and humidity variables. I don't feel like the plant really needs to be exposed to the stresses to achieve this however. It's proactive in it's defenses. It's developed these defenses through evolution over a millenia.
 
Lazerus00

Lazerus00

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Thanks @Organikz for chiming in, your opinion valued!

Yes @DemonTrich I am starting to see that running perpetual, all I could do is use the VPD chart as a guide to give me a rough outline. I am prolly not ever gonna be perfect on it but I gotta listen to my veg/flower tent as a whole since I am choosing too run multiple strains. I got to see what works well for the biggest number of plants at any given age....thanks for helping me work this out guys!!!
 
DrMcSkunkins

DrMcSkunkins

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I just dont have the luxury of mini splits and seperate environmentally controlled rooms. I have two tents in my moldy ass basement that has direct acess to crawl spaces with dirt floors. If I dont run the dehuey my rh gets over 65% at night, I just went and bought one when I saw a few spots on the largest buds from my last harvest that were just starting to get grey and fuzzy. I try to keep my temp aroung 75 with my central ac, maybe next tax season Ill be able to frame off a few rooms.
 
MIMedGrower

MIMedGrower

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I am pretty sure the vpd. Hart is meant for Greenhouse growing of tomatoes.

I run a multi strain multi stage perpetual and use 77 as a max temp and 60% max humidity indoors.

I need a humidifier and dehumidifier depending on season and weather here.

And proper air circulation is key but at 70% rh I would worry about mold. So I don't risk it with the meds.
 
EventHorizan

EventHorizan

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438
Woah woah woah! Things kicked off in here while I was doing some of my sleepz! Lots to respond to!! So leaving aside the above disagreement about budrot bc I am also in the belief that high RH grows are possible with good, consistent, and clean growing practices. So about a higher RH in flower. I can understand why you might want a higher RH in the beginning of flower but don't really understand wanting it for the 2nd half of flower. I have always had the belief that a lower RH has been shown to increase the plants drive to produce trichomes and be that greasy jewel we all want in our garden, at least thats what I have experienced. The higher RH in the beginning deff helps your plant grow to the fullest of its potential, especially when correctly supplementing co2. But what are your reasons of wanting such a high RH (anywhere near 60% and above) for final bud development? What benefits have you seen for your plants in late flower? I hope in no way this comes across as anything but inquisitive, I'm just curious to hear about the subject!
You know, im not for sure why you would want to follow the vpd the last 2 weeks. I be honest, cause I dont know benefits. I deff dont have a PhD.
But I know I just did... And I also on top of that, ran my buckets dry the last week and made all my leaves that were left die and fall off. I then cut the branches off the plant and hung them for 14 days at 60* and 63Rh. down from 65RH last week. If over 60% rh causes bud rot, then why do we dry out plants at 63% rh for 14 days with HARDLY any air flow????? just saying...
Oh by the way, I didnt have to cure, it was perfectly dried. A lil advice a fellow farmer gave me here and it was spot on! You actually start the drying process while the plant is still alive...

Maybe, just a guess, that when I run my buckets dry, but have 60 rh it drys from the roots up, and from the inside out, EXACTLY WHAT CURING DOES...
See it all goes together for me. I wouldnt run over 50% if your room isnt dialed enough to combat spikes. Mater fact vpd is for dialed in room IMO

I agree with both points honestly. If your plants SAR is high which a plant respirating and processing at full capacity should have, the brix should be so high that mold or mildew can't even attach to the tissue.

However sometimes our plants do see some weak moments and this is why a lot of people avoid high humidity. This is when the mold and bugs get in.

Many things along with cannabis thrive in high humidity. Just ask my broad mites. They loved it last run. I don't think they'll be returning from their neem showers.

This is a risky move but I personally had no issue with mold and the plants vigor doubles. Would I advise it and tell you 100% you won't get mold...nah. gotta keep them plants happy and healthy to avoid the mold.

I like old leadsled. He gave me a great quote.

"Pests are nature's garbage collectors and disease is the clean up crew."

I won't argue one way or another.
@DrMcSkunkins is just playing it safe which I totally understand. To some the risk outweighs the benefit to others the benefit outweighs the risk.

Josh steensland pointed out that his plants produce more co2 than his tanks are set to at night when running 75% during flower.
Excellent advice and i concur

Thanks @Organikz for chiming in, your opinion valued!

Yes @DemonTrich I am starting to see that running perpetual, all I could do is use the VPD chart as a guide to give me a rough outline. I am prolly not ever gonna be perfect on it but I gotta listen to my veg/flower tent as a whole since I am choosing too run multiple strains. I got to see what works well for the biggest number of plants at any given age....thanks for helping me work this out guys!!!
I dont see vpd being a good thing for perpetual.. I would go with 50% IMO
I just dont have the luxury of mini splits and seperate environmentally controlled rooms. I have two tents in my moldy ass basement that has direct acess to crawl spaces with dirt floors. If I dont run the dehuey my rh gets over 65% at night, I just went and bought one when I saw a few spots on the largest buds from my last harvest that were just starting to get grey and fuzzy. I try to keep my temp aroung 75 with my central ac, maybe next tax season Ill be able to frame off a few rooms.
Yep, its freaking expensive to get it set up right. I try to take a couple weeks worth of thought before getting on amazon.. But I promise you, when you do get to run vpd, you will be sold. Is there a chance for mold, yes most deff, but it requires more than just higher rh. Ive always been one to push the envelope. I went straight to hydro, knowing that everyone was saying, Dont do it, you will get mold.. lol ok I made a joke there... My point beiung that a lot of ppl said, i was stupid to try hydro first, and I would fail miserably. And that was after dropping 800 on a system and other equipment..
Then it was dont run a live res..
Wrong, it worked out great.
Then it was don't run over 50% rh in flower
My answer,,, Hey haters, you were wrong ,,, AGAIN...

So maybe, we should stop telling ppl that THEY CAN'T, and instead tell then, THEY CAN...
That is what is wrong with this world these days, we changing into sissys that play it safe.
Hell my mailman just left a note in my mail box, requesting that I move my mail box off my porch, so the mail man doesnt have to walk up steps, you know, the new trips, slips, and falls protocol... smh...
We are men.
We choose to go to the Moon! ...
We choose to go to the Moon in this decade and do the other things, not because they are easy, but because they are hard; because that goal will serve to organize and measure the best of our energies and skills, because that challenge is one that we are willing to accept, one we are unwilling to postpone, and one we intend to win....
On September 12, 1962, President Kennedy...
Thats the motto my parents instilled in me...
I dont use vpd cause its easy, i do it cause i want to go to the moon :)

I am pretty sure the vpd. Hart is meant for Greenhouse growing of tomatoes.

I run a multi strain multi stage perpetual and use 77 as a max temp and 60% max humidity indoors.

I need a humidifier and dehumidifier depending on season and weather here.

And proper air circulation is key but at 70% rh I would worry about mold. So I don't risk it with the meds.
That is a fair assessment, and I follow that, except before c02 my temps were 74 and 65% rh. But im going 75% rh in veg and first 3 weeks of flower with my c02 now. So I put my money where my mouth is...
Hopefully I dont get smacked in it :)
 

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