VPD and "outdoor" grow problems

[Grownsince95]

View attachment 2421067
For reference, here is the temps this very moment. 106 inside, but the door is closed down and several windows are open, with the 6" exhaust fan going at 100% and both Oscillating fans at 100%. It would be closer to outdoor temps with the door open, but then I think I run afoul with the laws if its not closed up. Also, I don't have the Humidifier or dehumidifier set up yet. Planning on doing that this weekend.

At that VPD your plants will close their stomata in a defense against dehydration and photosynthesis will grind to a halt. 3 kPa is one thing, 5.7 is a whole different ballgame.

 

[fordtough68]

At that VPD your plants will close their stomata in a defense against dehydration and photosynthesis will grind to a halt. 3 kPa is one thing, 5.7 is a whole different ballgame.

100%. This was what led me here. With increased humidity, which i should be able to achieve, I can get that vpd in much better shape, but this would mean humidity around 75-80% during the middle of the day! Crazy stuff

 

[Grownsince95]

100%. This was what led me here. With increased humidity, which i should be able to achieve, I can get that vpd in much better shape, but this would mean humidity around 75-80% during the middle of the day! Crazy stuff

The vpd doesn't have to be spot on just not so extreme. Give them 60% they'll drink a lot but be fine. Plus in southern OH you should have all the humidity you need soon enough lol.

 

[fordtough68]

The vpd doesn't have to be spot on just not so extreme. Give them 60% they'll drink a lot but be fine. Plus in southern OH you should have all the humidity you need soon enough lol.

Check this out. I came home, mind you this is 7 hours later, (the first one was at 10am, this is 5pm), and opened the door half way up, and here's the results. The other picture was full direct sun, this one is still direct but a tiny bit of overcast now.

 

[Bobcat.Branch]

Haha, honestly that was the only next logical conclusion for me! I can automate it, so it would be pretty easy to do, just more expense. If my wife would allow it, id set up a spare bedroom as a grow room. Ironically, its just us as all the kids have moved on, and we live in a 4 bedroom house, so this would be such an easy transition!

Cheaper and easier to replace the wife.

I kid I kid.

 

[fordtough68]

Cheaper and easier to replace the wife.

I kid I kid.

Man, you ain't kidding!!! Hahahaha

 

[Glomus]

I am a little worried about the root system, but I wouldn't use misting during the flowering stage at all. But yeah, I think youre right about the temps being just something to have to work with. Im using autos and have all of my seeds already, and 90% are from atlas seeds which really prioritize outdoor strains.

I was more referring to using misters to mist the walls of your greenhouse to increase the humidity.

 

[Grownsince95]

Check this out. I came home, mind you this is 7 hours later, (the first one was at 10am, this is 5pm), and opened the door half way up, and here's the results. The other picture was full direct sun, this one is still direct but a tiny bit of overcast now. View attachment 2421212

That you can work with

 

[RoadKillSkunkHunt]

Don't worry about VPD outdoors. Your stuck with whatever mother nature gives you. Outdoor growing is very different from indoors. It's all about providing as much air circulation as you can and then dealing with problems as they show up( bugs, WPM, bud rot, etc). I grow in a poly tunnel in summer and it's a challenge but I love it. Start a grow thread and there's lots of good people here to help you along. Good Luck

Yep ... air flow, air flow, air flow ... You need to intake fresh air, exhaust hot and humid air, and also oscillating fans to move it all around. I tried with varying degrees of success to run in a 10' x 20' x 7 hoop style polycarbonate greenhouse.

Here's a picture of the front showing the exhaust fan. It's a louvered attic fan. It moves a lot of air.

Here's a picture of the back. It shows the opening, although I have not yet installed the fan in that picture. It's the same as the one on the front except the louvers are on the inside. When I finished it, the back has a furnace filter and a a grate over it to keep everything in place.

Inside the greenhouse, I have 16" 0scillating fans. There's tons of air movement but I still have problems once the fall rolls around and we're hitting the dew point every night. The wet buds and all the extra moisture is a calling card for mold/mildew/rot issues.

The whole premise behind using a greenhouse is to keep your plants as sheltered and as dry as possible so don't be using a sprinkler or misting plants, or anything like that. You don't want any extra humidity than you can help. Mother nature and transpiring plants will produce enough moisture all on their own.

I can give you a long list of pointers and tips but your success regardless if you do everything exactly right will still come down to the environment that mother nature gives you. You can't dehumidify or air condition a back yard greenhouse very well. All you will do is run up your electric meter. Instead, plan on lots of air flow, invest in a battery operated leaf blower to keep everything dry when moisture is dripping from the roof of the greenhouse and hope mother nature smiles on your efforts and gives you your just reward.

Best tip I can give you is run auto-flowers if your summer weather doesn't run until the 1st of November.

 

[fordtough68]

Yep ... air flow, air flow, air flow ... You need to intake fresh air, exhaust hot and humid air, and also oscillating fans to move it all around. I tried with varying degrees of success to run in a 10' x 20' x 7 hoop style polycarbonate greenhouse.

Here's a picture of the front showing the exhaust fan. It's a louvered attic fan. It moves a lot of air.




View attachment 2421335


Here's a picture of the back. It shows the opening, although I have not yet installed the fan in that picture. It's the same as the one on the front except the louvers are on the inside. When I finished it, the back has a furnace filter and a a grate over it to keep everything in place.

View attachment 2421334

Inside the greenhouse, I have 16" 0scillating fans. There's tons of air movement but I still have problems once the fall rolls around and we're hitting the dew point every night. The wet buds and all the extra moisture is a calling card for mold/mildew/rot issues.

The whole premise behind using a greenhouse is to keep your plants as sheltered and as dry as possible so don't be using a sprinkler or misting plants, or anything like that. You don't want any extra humidity than you can help. Mother nature and transpiring plants will produce enough moisture all on their own.

I can give you a long list of pointers and tips but your success regardless if you do everything exactly right will still come down to the environment that mother nature gives you. You can't dehumidify or air condition a back yard greenhouse very well. All you will do is run up your electric meter. Instead, plan on lots of air flow, invest in a battery operated leaf blower to keep everything dry when moisture is dripping from the roof of the greenhouse and hope mother nature smiles on your efforts and gives you your just reward.

Best tip I can give you is run auto-flowers if your summer weather doesn't run until the 1st of November.

Thank you very much! I have 2 Oscillating fans in there now, and once I opened up the door today, the temps and humidity fall back to a reasonable level. Unfortunately, im not sure how well this will fall within the law here, as we can have up to 12 plants but they can't be plopped in the back yard and mist be "in a secured space like a greenhouse". Keeping the door open doesnt sound secure, so I feel I may be crossing a line. Im going to just give it a try and see what happens and hope for the best, as the worst that will happen for a first offense is a fine. Otherwise it must be indoors. All of my seeds are autoflowers so I should be able to get at least one harvest if all goes well. The part that gives me the biggest chuckle of this whole process, is that I don't smoke anymore. I quit 20 years ago! I've just always wanted to grow, and feel like this will be a unique challenge!

 

[fordtough68]

Yep ... air flow, air flow, air flow ... You need to intake fresh air, exhaust hot and humid air, and also oscillating fans to move it all around. I tried with varying degrees of success to run in a 10' x 20' x 7 hoop style polycarbonate greenhouse.

Here's a picture of the front showing the exhaust fan. It's a louvered attic fan. It moves a lot of air.




View attachment 2421335


Here's a picture of the back. It shows the opening, although I have not yet installed the fan in that picture. It's the same as the one on the front except the louvers are on the inside. When I finished it, the back has a furnace filter and a a grate over it to keep everything in place.

View attachment 2421334

Inside the greenhouse, I have 16" 0scillating fans. There's tons of air movement but I still have problems once the fall rolls around and we're hitting the dew point every night. The wet buds and all the extra moisture is a calling card for mold/mildew/rot issues.

The whole premise behind using a greenhouse is to keep your plants as sheltered and as dry as possible so don't be using a sprinkler or misting plants, or anything like that. You don't want any extra humidity than you can help. Mother nature and transpiring plants will produce enough moisture all on their own.

I can give you a long list of pointers and tips but your success regardless if you do everything exactly right will still come down to the environment that mother nature gives you. You can't dehumidify or air condition a back yard greenhouse very well. All you will do is run up your electric meter. Instead, plan on lots of air flow, invest in a battery operated leaf blower to keep everything dry when moisture is dripping from the roof of the greenhouse and hope mother nature smiles on your efforts and gives you your just reward.

Best tip I can give you is run auto-flowers if your summer weather doesn't run until the 1st of November.

I do have another question you could answer for me. What about the humidity at night? Currently, our humidity is near 100% at night. The hoop house is reaching the same with the door open or shut, same result. Should I even worry about it at all? I was thinking about closing it at night and running a dehumidifier, then opening again in the morning before work. My only issues are that this is a lot to do and I'm trying to be as hands off as one can be and don't want "daily" routines like this if I can avoid them. The other, is that im not sure it would even work. I should be deep into flower in July, so I'm not sure if the humidity in July is that high or if its lower. I'm also not sure if it will effect the veg stage with the wild swings from 100 down to 20-30% each day.

 

[Glomus]

Thank you very much! I have 2 Oscillating fans in there now, and once I opened up the door today, the temps and humidity fall back to a reasonable level. Unfortunately, im not sure how well this will fall within the law here, as we can have up to 12 plants but they can't be plopped in the back yard and mist be "in a secured space like a greenhouse". Keeping the door open doesnt sound secure, so I feel I may be crossing a line. Im going to just give it a try and see what happens and hope for the best, as the worst that will happen for a first offense is a fine. Otherwise it must be indoors. All of my seeds are autoflowers so I should be able to get at least one harvest if all goes well. The part that gives me the biggest chuckle of this whole process, is that I don't smoke anymore. I quit 20 years ago! I've just always wanted to grow, and feel like this will be a unique challenge!

I wouldn't worry about the law about a "secured space" honestly a greenhouse tarp over your plants and a lock on the gate to your backyard could be considered a secure space. I think that law is about not offending neighbors or attracting an element of thieves. Luckily you shouldnt have to worry about the later as cannabis isnt worth much these days lol. Not even worth the hassle to steal.

 

[RoadKillSkunkHunt]

I wouldn't worry about the law about a "secured space" honestly a greenhouse tarp over your plants and a lock on the gate to your backyard could be considered a secure space. I think that law is about not offending neighbors or attracting an element of thieves. Luckily you shouldnt have to worry about the later as cannabis isnt worth much these days lol. Not even worth the hassle to steal.

The above post pretty well says it all. I do have a lock on my greenhouse. I have a padlock on my backyard fence. Even if I leave the top doors open but lock the bottom of the dutch doors, I am technically still within the law ... at least where I live.

P.S. Best way to handle night time humidity is to leave doors open and the fans running. You will also want a way to dry the glass in the morning as well as your plants. Most people I know use a battery powered leaf blower for this task.

 

[fordtough68]

Yep ... air flow, air flow, air flow ... You need to intake fresh air, exhaust hot and humid air, and also oscillating fans to move it all around. I tried with varying degrees of success to run in a 10' x 20' x 7 hoop style polycarbonate greenhouse.

Here's a picture of the front showing the exhaust fan. It's a louvered attic fan. It moves a lot of air.




View attachment 2421335


Here's a picture of the back. It shows the opening, although I have not yet installed the fan in that picture. It's the same as the one on the front except the louvers are on the inside. When I finished it, the back has a furnace filter and a a grate over it to keep everything in place.

View attachment 2421334

Inside the greenhouse, I have 16" 0scillating fans. There's tons of air movement but I still have problems once the fall rolls around and we're hitting the dew point every night. The wet buds and all the extra moisture is a calling card for mold/mildew/rot issues.

The whole premise behind using a greenhouse is to keep your plants as sheltered and as dry as possible so don't be using a sprinkler or misting plants, or anything like that. You don't want any extra humidity than you can help. Mother nature and transpiring plants will produce enough moisture all on their own.

I can give you a long list of pointers and tips but your success regardless if you do everything exactly right will still come down to the environment that mother nature gives you. You can't dehumidify or air condition a back yard greenhouse very well. All you will do is run up your electric meter. Instead, plan on lots of air flow, invest in a battery operated leaf blower to keep everything dry when moisture is dripping from the roof of the greenhouse and hope mother nature smiles on your efforts and gives you your just reward.

Best tip I can give you is run auto-flowers if your summer weather doesn't run until the 1st of November.

Here's an update for today. Yesterday at the same time I took a screenshot under a little less heat, and the results are much better with the door half open. I think i can work with this! Ill make some more adjustments over the coming days. I wonder if in extreme heat, I could put the misting system on the outside of the hoop house to help keep temps low without hurting anything? Seems like it would be a good thing if inside temps get over 95 degrees. I can automate it and control it anywhere, so it wouldn't be too much of a hassle at all.

 

[RoadKillSkunkHunt]

Here's an update for today. Yesterday at the same time I took a screenshot under a little less heat, and the results are much better with the door half open. I think i can work with this! Ill make some more adjustments over the coming days. I wonder if in extreme heat, I could put the misting system on the outside of the hoop house to help keep temps low without hurting anything? Seems like it would be a good thing if inside temps get over 95 degrees. I can automate it and control it anywhere, so it wouldn't be too much of a hassle at all.

Here's the thing about that ... Once its filled with maturing plants it won't behave the same for you as it is right now. There will be no substitute for due diligence come fall in keeping everything dry. Plan on having a busy fall.

 

[fordtough68]

Here's the thing about that ... Once its filled with maturing plants it won't behave the same for you as it is right now. There will be no substitute for due diligence come fall in keeping everything dry. Plan on having a busy fall.

I've got my electric leaf blower on standby! Hopefully the things are curing by fall lol. Im starting Germination this weekend.

 

[RoadKillSkunkHunt]

I've got my electric leaf blower on standby! Hopefully the things are curing by fall lol. Im starting Germination this weekend.

Are you growing photoperiod plants? If so, those will mature based on the genetics and won't start flowering until you approach 14 hrs of sunlight. Where I am at, that happens towards the middle of August. That information is available on weather related sites like AccuWeather. From there, count out the number of weeks or days so you have a general idea when they will be ready.

If you're growing auto-flowers, you should be fine. I'm not running cannabis outdoors this summer but in the past I have successfully run 2 batches of autos before fall weather has set in. I'd start the first run in early April indoors and then move it to the greenhouse in May. Then mid to late May, I would start my second run. My first would be harvested in July and my second run would be harvested late August/early September. Autos will finish in a short northern summer.

 

[fordtough68]

Are you growing photoperiod plants? If so, those will mature based on the genetics and won't start flowering until you approach 14 hrs of sunlight. Where I am at, that happens towards the middle of August. That information is available on weather related sites like AccuWeather. From there, count out the number of weeks or days so you have a general idea when they will be ready.

If you're growing auto-flowers, you should be fine. I'm not running cannabis outdoors this summer but in the past I have successfully run 2 batches of autos before fall weather has set in. I'd start the first run in early April indoors and then move it to the greenhouse in May. Then mid to late May, I would start my second run. My first would be harvested in July and my second run would be harvested late August/early September. Autos will finish in a short northern summer.

Yep, all autos. I didn't want to have to mess with the light on top of everything else. I'm hoping my wife will come around and let me put in a 8x8 tent in one of our spare bedrooms, that conveniently stays right around 68 degrees all year. Lol

Then im switching to photo!

 

[RoadKillSkunkHunt]

Yep, all autos. I didn't want to have to mess with the light on top of everything else. I'm hoping my wife will come around and let me put in a 8x8 tent in one of our spare bedrooms, that conveniently stays right around 68 degrees all year. Lol

Then im switching to photo!

I run photos indoors. Usually 2 runs a year. I'm finishing up one right now. I'll be harvesting soon.

 

[fordtough68]

I run photos indoors. Usually 2 runs a year. I'm finishing up one right now. I'll be harvesting soon.

Send some pics!