Pm in the grow room

Ok so I'm at the end of week 5 of flower. I just noticed the pm about a week ago tried 1tbsp baking soda with a few squirts of dawn soap to a gallon of water. Not seeing much result tried it twice over the course of a week. Was thinking of getting sodium carbonate but I worry that shit on the nugs will make harsh smoke. So I ask what do I do guys hydrogen peroxide washes till the end? This is my first pm encounter indoors. The big one is a auto sour kush the other is a auto cream. If you need any more info please ask I feed them with general hydro and they r hydro set up. Grow room is 70-80 and 20-40 rh at night sometimes I'll hit mid to low 60s tho even with fans on low I live in Maine its cold af now. Thanks guys

Anyone out there????

Do you have a dehumidifier on when the lights shut off either in the grow or in the the same room. Also more exhuast and airflow some strains need pruning big time like bubba kush it will choke itself out leaves on top of one another. Size of grow is it in a closet or tent? What size inline fan and is it on 24/7

Sorry here r the rest of the pics didn't realize they didn't load

Im in a closet with 6 inch exhaust fan def enough turn over plus 2 box fans 75-80 daytime 66-70 at night rh is 20-40 max. I tried the no defoliation[ I since defoliated after finding pm] method with this run and I believe that caused it along with cold nite temps its winter now here in maine

If your hygrometer accurate?

Ya I got two of them in the room. That's the temp and rh now trying to keep it there all the time. I had a big swing a month back when winter started I think that started it I'm just trying to keep it at bay now

Tflynnsl18 said:

Was thinking of getting sodium carbonate

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Sodium Bicarbonate is baking soda. Potassium bicarbonate is a little better for your plants. Both are alkaline and will raise the pH. PM likes an acidic environment so any foliar application should always be pH'd to bring it up around 10 - 11.

Thing is, it's difficult to get 100% coverage, even with a surfactant, and the application raises the RH% so it's not ideal by any means. Some use a sulfur vaporizer because it gets better coverage but I don't recommend that.

The environment is the key. Too low can be problematic and having swings from low to high RH% is exactly the recipe for PM. I never had PM growing for over 20 years in Missouri where the RH% was always high, it never got super low. Here in Colorado I learned what PM is. The RH% is so low here, often in the teens. That combined with the humidity transpired in a confined space can make for big RH% swings. Say you vent for heat, the blower cycles and the RH% plummets. Lets say that's causing a swing from the upper 40's down into the lower 30's. That could be enough to make PM pop up.

I have seen PM pop up when you have low RH% like in the 30's most of the time and it hits the upper 40's for just 15 - 30 minutes after lights out. It doesn't take long as PM grows really fast. If you are noticing the growth when the lights come on (it happened in the dark) then this is the likely situation.

Do you have a hygrometer that will give you a log showing the RH% and temperature over time (not just high and low)? That can be extremely handy.



That chart shows one of my flowering rooms. You can see the temp drop when the lights go off at 3:45 am. The humidity also spikes.

Here is a thread with more on the subject. https://www.rollitup.org/t/why-does-my-humidity-spike-at-lights-out.1000927/

Thanks guys I didn't realize pm can strike with rh in 30 to 40s. Thanks for all the info and feedback guys. Not really sure what to do just gonna maintain it I guess tor a few more weeks till its done

Chop em now or continue depending how bad. But garbage any buds w actual PM on it.
Any treatment will just help it from spreading, I still wouldnt smoke the PM after treatment(s).
Sucks but way she goes.

Wipe down entire room w bleach and spray sodium bicarbonate etc...

Renfro said:

I have seen PM pop up when you have low RH% like in the 30's most of the time and it hits the upper 40's for just 15 - 30 minutes after lights out. It doesn't take long as PM grows really fast. If you are noticing the growth when the lights come on (it happened in the dark) then this is the likely situation.

Do you have a hygrometer that will give you a log showing the RH% and temperature over time (not just high and low)? That can be extremely handy.

View attachment 4433481

That chart shows one of my flowering rooms. You can see the temp when the lights go off at 3:45 am. The humidity also spikes.

Here is a thread with more on the subject. https://www.rollitup.org/t/why-does-my-humidity-spike-at-lights-out.1000927/

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Ya I have one that monitors that my swing is usually 25 rh during day and 35 40 at night when lights go out.

Well I suggest minimizing that RH% swing and avoid the times of super low RH%. You may actually have to add some RH% when the lights are on if just reducing the lights on dehumidification doesn't do the trick. I have to use a higher daytime RH% setting on my dehu than I do at night.

There is a foliar spray you can do with one part water and nine parts milk. It helps on my other plants. I don’t know if you can spray it on cannabis flowers. Maybe someone that know will chime in. Good luck

Tflynnsl18 said:

Ok so I'm at the end of week 5 of flower. I just noticed the pm about a week ago tried 1tbsp baking soda with a few squirts of dawn soap to a gallon of water. Not seeing much result tried it twice over the course of a week. Was thinking of getting sodium carbonate but I worry that shit on the nugs will make harsh smoke. So I ask what do I do guys hydrogen peroxide washes till the end? This is my first pm encounter indoors. The big one is a auto sour kush the other is a auto cream. If you need any more info please ask I feed them with general hydro and they r hydro set up. Grow room is 70-80 and 20-40 rh at night sometimes I'll hit mid to low 60s tho even with fans on low I live in Maine its cold af now. Thanks guys

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I have had good luck with 3% peroxide brown jug from wally world. no harm to the flowers,spray every couple days till the end.

Renfro said:

Well I suggest minimizing that RH% swing and avoid the times of super low RH%. You may actually have to add some RH% when the lights are on if just reducing the lights on dehumidification doesn't do the trick. I have to use a higher daytime RH% setting on my dehu than I do at night.

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Very interesting I didn't realize that any rh swing brings pm on I thought it was only brought on by high rh and then a swing to lower rh with cold temps. So I need to keep everything in a ten percent range? Say 30-40 and try for 70-80 temps with light on n off? I think I can achieve temps of 70 plus 24/7 prob is its dry here so my rh is with no dehumidifier running the heater is on at home so its dry hot air

thumper60 said:

I have had good luck with 3% peroxide brown jug from wally world. no harm to the flowers,spray every couple days till the end.

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Yes I have been looking into this seems to be my only option left

This is my temp after 12 hours of lights on with my two fans on and the exhaust running. I was thinking of putting a hose on my exhaust to take away some sucking power yo keep the temp up what you guys think? I just pull up and out from the ceiling atm

Tflynnsl18 said:

Say 30-40

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If I had to nail down a range I would do 37 - 47. If I lock that in I am good to go.

Alright thanks I'm gonna try and get this under control.