Week 3 flower, lights off -> ideal humidity?

It's day 21, week 3 since you flipped. You just watered all your plants in the morning. Now it's night time, lights flipped off.... what's your ideal temp & humidity %?

I'm looking at 76-78F & 45-47% RH. Is that in a good window?

For temps anything between 70 and 80 degrees is fine. Don't have more than a 10 degree diff between lights on vs off.

For %RH aim 40-60.

ebgms said:

For temps anything between 70 and 80 degrees is fine. Don't have more than a 10 degree diff between lights on vs off.

For %RH aim 40-60.

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So 50 even 60% RH is safe in flower?

DrDukePHD said:

So 50 even 60% RH is safe in flower?

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Yes but it depends at what stage of flowering. Although I adjust following VPD I prefer to go down to 50 maximum 55% at the end of flowering especially if there is not enough airflow to ward off serious problems. I'll leave you a site to understand what range to stay in during all stages of growth. (I'm not saying you can't get to 60% but I would rather not risk it especially if you have nice big flowers and not optimal conditions)


In the site ,under the graph, you will find a legend to read the data you got and they give you guidelines to figure out what range you should be in based on your current stage

DrDukePHD said:

It's day 21, week 3 since you flipped. You just watered all your plants in the morning. Now it's night time, lights flipped off.... what's your ideal temp & humidity %?

I'm looking at 76-78F & 45-47% RH. Is that in a good window?

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You could let RH rise a bit if you want to.
You're running around 1.6. That's pretty dry. 1.2 - 1.4 is usually the place to be @ during flower.

I'd never chase a vpd chart. Higher rh in veg, lower (50 or under) in flower. Just don't go too low.

How humid you can allow depends on your environment, if you’re growing at home best to keep it between 45 and 55 from mid flower on otherwise you run the risk of mold, bud rot etc. if you’ve got a sealed room or a commercial facility with hocl fogger or pco generator go ahead and follow the vpd charts. Even the nearest cleanest mf is gonna have airborne contaminants in their home or bring them in on their clothes.

Jjgrow420 said:

I'd never chase a vpd chart. Higher rh in veg, lower (50 or under) in flower. Just don't go too low.

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Right now lights on im at 40. Sometimes I'm running at 37-38%. Is that a problem? Would hate to have to run humidifier during flower.

DrDukePHD said:

Right now lights on im at 40. Sometimes I'm running at 37-38%. Is that a problem? Would hate to have to run humidifier during flower.

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I think it also depends on the cultivar.
The lower your rh the more water they will pull and ec can rise in your medium. Can u slow your extraction fan down some? That usually helps the rh buildup a bit