NEED ADVICE ON TEMP AND HUMIDITY

Hey everyone I have not been flowering my plants for a week. I upgraded my lights to a 600W HPS right before I started to flower and have been having issues with it. I can't seem to get the proper ventilation in the tent. I have a 6 in inlet fan blowing air-conditioned air into the tent along with a 6 in outlet fan attached to the back end of the reflector. I also just added another vent attached to the air conditioner no fan though. At the highest my temp got to 104 and the lowest it went to 55 so I have quite a range. The vast majority of the time it ranges from 68-81 and the humidity fluctuates between 25-45% with a 1.5 gallon humidifier. I was wondering what a good target temp and humidity should be for flowering. Also the light can be dimmed and I am only growing 2 plants so I was wondering if I should try dimming the lights or will that reduce my yield?
Any recommendations would be greatly appreciated.

The 68-81 and 25-45% is fine.

Make sure you are not pushing more air in to the tent then you are pulling out.

75 degrees Flowering with around 25 % humidity. Humidity too high can cause mold issues. If your only vegging, humidity can be higher.

Awesome thanks guys, any reason why I shouldn't have more air coming in than going out? Not doing it just curious.

I have a 4" fan sucking in cool air on the tent floor( not pushing) and an 8" fan sucking air out through the light's hood. MY 8" fan is in the attic connected to a 6" flexible duct sucking air out of the tent and venting it through my house's roof vents. When it comes to inline fans, it is very important you do not try to push air, but rather pull it, that's what they are made for. Ideal RH is between 40%-65% and Ideal temp is about 65-80 degrees F.

newbiegrow12 said:

Awesome thanks guys, any reason why I shouldn't have more air coming in than going out? Not doing it just curious.

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Because if you are trying to vent air out, you need a negative pressure in your tent or grow area. More air in will result in positive pressure. This will cause odors to leak out of the tent. You want odor's only way out to be through the 6" fan, not though your zippers and tent vents + your plants will breath better.

Cobnobuler said:

75 degrees Flowering with around 25 % humidity. Humidity too high can cause mold issues. If your only vegging, humidity can be higher.

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25% humidity? that seems awful dry," bug infestation" dry.

I live in the driest state in the US so humidity is hard to increase. I haven't had any problems with bugs. The fan leaves got pretty burnt when I switched from CFLs to HPS and didn't have the proper ventilation causing the temp to soar to 104. I have fixed the problem and all new growth is perfectly healthy.

Smootherpete said:

Because if you are trying to vent air out, you need a negative pressure in your tent or grow area. More air in will result in positive pressure. This will cause odors to leak out of the tent. You want odor's only way out to be through the 6" fan, not though your zippers and tent vents + your plants will breath better.

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I didn't know that, when I was vegging I had positive pressure because I only had an inlet fan blowing room temp air into the tent to help air flow because the CFLs didn't give off very much heat. Currently the inlet and outlet fans are both on dimmers and I lowered the inlet fan speed a little to provide negative pressure. Hopefully this will also help with the humidity levels.

Do you know if its possible to give the plants too much light? The seed bank I bought the seeds from gave me a guide that says I should try to get about 2000 Lumens per square foot and my tent is 32x32x70 with 89000 lumens. The guide said only to go higher if you plan on providing extra CO2 and I do not have the means to do so, I was wondering if dimming the light to 50% would reduce the yield or because I only have 2 plants it would help with temp control?

newbiegrow12 said:

I live in the driest state in the US so humidity is hard to increase. I haven't had any problems with bugs. The fan leaves got pretty burnt when I switched from CFLs to HPS and didn't have the proper ventilation causing the temp to soar to 104. I have fixed the problem and all new growth is perfectly healthy.



I didn't know that, when I was vegging I had positive pressure because I only had an inlet fan blowing room temp air into the tent to help air flow because the CFLs didn't give off very much heat. Currently the inlet and outlet fans are both on dimmers and I lowered the inlet fan speed a little to provide negative pressure. Hopefully this will also help with the humidity levels.

Do you know if its possible to give the plants too much light? The seed bank I bought the seeds from gave me a guide that says I should try to get about 2000 Lumens per square foot and my tent is 32x32x70 with 89000 lumens. The guide said only to go higher if you plan on providing extra CO2 and I do not have the means to do so, I was wondering if dimming the light to 50% would reduce the yield or because I only have 2 plants it would help with temp control?

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Dimming light will reduce yield for sure. You can only give too much light if your plants are too close to the light, that distance depends on how cool your light is and the type of light. I have a 600W and I try to keep the tops at least 14" from the very well vented bulb. Too close to the bulb will dry out the top leaves/buds but will not give the plant a "light overdose" .

No co2=75 degrees
If co2 is used you can run a hotter tent/room @ 80-90 degrees.
Both cases keep your humidity around 40-50 if you can.

Smootherpete said:

25% humidity? that seems awful dry," bug infestation" dry.

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Well, I would have to add that in my case, my growroom is in my old city basement where I have to deal with combating mold. I have to be especially diligent about humidity. Vegging is no issue but flowering is another matter.

Cobnobuler said:

Well, I would have to add that in my case, my growroom is in my old city basement where I have to deal with combating mold. I have to be especially diligent about humidity. Vegging is no issue but flowering is another matter.

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I see, but 25% RH is still lower than recommended levels for flowering. Depending on how well you vent your grow area and how many plants you have, those levels might increase during flowering since the plants release a lot of moisture in the air when they flower. Your dehumidifier will be working extra hard. The only problem I could see with lower RH levels aside from promoting pest infestation(mostly spider mites) would be less than average yield. Your plants might try to save it's moiture by curling its leaves downwards but I think they would still flower and yield buds.

Just thought I would add, I am super excited! Both my plants showed they are girls today so I couldn't be happier as this is my first grow and was worried I'd get a male. I did have a question though, the White Widow started flower at 1.5ft with 36 growth tips I was wondering what I should expect to yield from her?

newbiegrow12 said:

Hey everyone I have not been flowering my plants for a week. I upgraded my lights to a 600W HPS right before I started to flower and have been having issues with it. I can't seem to get the proper ventilation in the tent. I have a 6 in inlet fan blowing air-conditioned air into the tent along with a 6 in outlet fan attached to the back end of the reflector. I also just added another vent attached to the air conditioner no fan though. At the highest my temp got to 104 and the lowest it went to 55 so I have quite a range. The vast majority of the time it ranges from 68-81 and the humidity fluctuates between 25-45% with a 1.5 gallon humidifier. I was wondering what a good target temp and humidity should be for flowering. Also the light can be dimmed and I am only growing 2 plants so I was wondering if I should try dimming the lights or will that reduce my yield?
Any recommendations would be greatly appreciated.

Click to expand...

Tents are a nightmare mate honest,the only way to get it keyed is use a lower light,but that is aa no no yeild wise have ya thought about led or just get a bigger out let and a in let thats about 2 ince smaller but if its warm bring air in from a cool room rather than a window because if its 26 out side your bringing that in your room,that is before heat from the lights.

You will find that the humidity is high because of the heat been thrown out by the lights.
Took me a long time to get it at 28 summer lights on 28 winter lights on sometimes will rise to 28/30 but that dont worrie me if the plants look ok dont worrie though i know someone who pulls 12 oz dry from a room that reaches 100 dg.so if they look well and are clones not femanised seeds go on how the plants look not the temps,to be honest i ph once when i first start but use ec trunchen every feed,and have took away the temp gage just because it can make you do something that will cause damage.

If the plants are only young then dimming the light may help but might also cause strech Look for somewhere cooler to pull air from it may just be your pulling hot air vented out back in or the air from the window if that is where your pulling it from is too warm

put a 18 ltr bucket in a chest freezer if you have one,once it has been in there 3 days and rock hard ice cut a hole the size of the duct in the top of the bucket,them freezer chest are perfect then put small holes around the water line well ice line to let air in then connect to in let and your bring cool air in.

a very cheap but useful way of makeing a cheap ac unit and it works but would not advice in bud unless you keep your eye on it once it starts to defrost swop with another a bit of work i know but hope this helps got to have holes a good few round top of bucket though to let air in,Best to have 2 buckets so has soon has one defrost next one ready

Be careful in flowering though because it may higher your humidity,you really want 20 lights off 28 lights on humidity around 40/50 % during flowering abit higher in veg if you have high humidity try not to top till that is sorted or it can cause stem rot from the cuts

Just thought I would add, I am super excited! Both my plants showed they are girls today so I couldn't be happier as this is my first grow and was worried I'd get a male. I did have a question though, the White Widow started flower at 1.5ft with 36 growth tips I was wondering what I should expect to yield from her?

Would using tap water in my humidifier ruin my plants?