question humidity/ Temp

[Catfish22]

Hi ya'll, first grow and I seem to have avoided most problems. I do have a couple questions if you could share some knowledge nugs, please!

I can run at 70% RH/80°F exhaust off or 40%/75° exhaust on. In your experience/opinion which is the better combo?

Also, running autos, when should I bring the bloom switch on.

Apologies for the pics, for reference they are in 3 gal buckets.

At 21days:

[JeffInCanada]

Hi Catfish22 ,
The photos did not come through for some reason. I cannot view them. No matter, A bit of a dilemma I guess eh. Exhaust off is a bit too humid and warm and exhaust on is a bit too low for the humidity. If I had to choose between the two I would pick exhaust on. The correct humidity and temperature can be difficult to hit correctly. If you really want to really dial it in you need to learn about Vapour Pressure Deficit. I do not really understand it fully myself but it has to do with understanding the way the plant takes up nutrients and transpires moisture from it's leaves. And having the best temp and humidity for this. Below is a podcast that explains it in detail. And of course there is the GWE humidity page here: https://www.growweedeasy.com/humidity
If you are asking when to switch to bloom nutes, I usually wait until I see the first sign of flowering. Of course with your autos you will not be switching the light on times for flowering.

[Catfish22]

Hi. Yeah I've studied up on VPD some. My chart shows that I have a decent VPD at 70% and 80°F, not so much at 40%/75°. My concern is at the higher RH these still sorta young sprouts might lay off on root growth and suck water out of the air.

I think you misunderstood my bloom question, I have a veg switch and a bloom switch on my lights. I'm still running in veg right now. I was wondering when I should switch the bloom on. I'm going to run 18/6 for the entire grow.

I'm glad you mentioned nutes though, I had studied Nebula's auto/coco schedule and am going by that. Thanks for your response and be safe, grow well.

[Smokesteve]

I agree with exhaust on, when I used that type of light once the plants had a few sets of leaves I ran both veg and bloom

[Catfish22]

Thanks, I was kinda thinking the same thing.

[CaptainWiese91]

I run both switches when doing autos.

[buffalobuds]

Good Day ....Temp. and humidity are very important in the Germ. and seedling stage,warm and not real dry. But you must remember this is a weed,grows by it's self all over the world. They put up with all kinds of weather,once their start growing they may have a very dry or wet season. They can adapt to what ever is thrown at them . So down the line it's not that important ...........Peace