Optimum temperature and humidity

I was wondering how important humidity is for a grow mine is very low like 30% or less and I tried to keep the temperature in the low 80s


If you can maintain 50% RH thru out the grow you would be good.
30% is a bit low 75 to 80F is ideal


That’s much better than I hoped I knew the temperature wasn’t too bad but I thought the humidity should be around 75 to 80%. I’m not even sure if my lights could handle that much humidity thanks for your response


30% is a bit low for temps over 80f but its not catastrophic.

80f is a good temperature, if you could get over 50% in veg and just under 50% in flower would be ideal for 80f.

But with low humidity things just work a little differently, their transparation rate will be increased.
Basically meaning they will go through more water just like we would if we was working on a hot dry day in the sun :grin:


As stated, the humidity is low. Good weed can be grown still in low humidity. One of the most knowledgeable growers on here (hellraiser) grew grade “a” weed consistently in low humidity. Not ideal but can be done. If doable, just add a humidifier.


Thanks this is my second grow the first one did come out pretty good just had a low yield. I did add a humidifier it’s only been on for about an hour and a half I set it up outside the tent venting in but so far no Rising humidity my only worry is how much humidity the light can handle( vivosun 400 watt LED in a 4x4 tent


The light should be just fine long as no actually “dew drops” develop on it and it would take alot to do that i believe.

So how big are they so far?
Air flow is important but not so much when they are small.
I sometimes through the first few weeks of veg will turn my exhaust fan down so it holds humidity inside better.
You can’t really do this in flower of course or late in veg if you tent is stuffed. .
But it may help take advantage or a little accelerated growth in early to mid veg.

Keep air moving inside but maybe slow down the ventilation circulation is what im trying to say :sweat_smile:


Just realized the 400w in a 4x4.
Im sure thats vivosun says that light is good for a 4x4 and as you’ve seen. It works but low yeild. It will take a little more light to fully light that space.
I have 720watts in a 4x6 space for example, it yeilds me on average 3lb a grow


I was using some crappy grow lights before I’m only 6 weeks into this grow but so far things are looking much better and I’m just growing for myself so if I get a pound out of a tent I’ll be a happy camper


Growing medium can play a big roll in yeild.
Going with coco-coir and perlite rather then soil for example results in increased yeild.
It’s different then soil but I honestly think its alot easier to master then soil.

I’ve no idea what you grow in just that most start with soil, me included. You couldn’t make me go back now after trying coco-coir :sweat_smile:


A grow light should be rated to handle the higher humidity that growing can induce. At 30ish rh that you have, i would not worry about trying to add more. The rh that would make me concerned would be too high for growing to be effective and at a great risk of a mold.

Since you only had humidifier on for hour and a half, i would not rule out its as high as it could go. Give it 24 hr to see. Make sure when light is off that it does not get to high using humidifier.

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Okay this is where I make everyone cringe but please don’t anyone injure yourself I’m using Miracle Grow I know I should but it’s really the only thing I have access to and I haven’t had any problems with it really but on my next grow I will try some coco
coir I’m guessing I’ll start that around June assuming I’m correct 20 weeks of vegetation eight weeks of flowering


Im actually on your side with this one :rofl:
Nothing wrong with miracle grow if you know what your doing…

There is better option but it works just fine :slightly_smiling_face:

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I used only miracle gro during the ninety’s. It can be done effectively. I remember using jacks classic 20-20-20 even back then as well.


You have to use the Right Mix for seeding or potting and I use straight water for the first two weeks. I haven’t had any burning yet although I may have gone a bit too far on the trimming. I’ll send some pictures shortly


Bwhahaha im with @Poseidon1 i can remember using miracle grow in the 90s. I that was back when you didnt know what you had until you flipped and had to pull males…


Try VPD vapor pressure deficit!

Charts like the one below are available online… They take into account the temp, humidity and leaf temperature.

This way you can maximize your plants growth by having your plants environment set correctly.

There’s also DLI… Daily light integral

This takes into account the amount of light your plants receive per day… You take a reading, or more then average, with a light meter take that measurement or average of measurements and calculate the dli.

This way you don’t provide more or less light than needed to grow proper bud.

I hope this helps.

@JOKERSTR Try Roots Organics Original.

With proper watering my plants haven’t been happier since switching…

Also… After trying many soils…

Roots Organics Original I have had, As long as watering correctly as over watering can breed bugs… Like fungus gnats, any pest issues. At all.

Holy smokes 20 weeks veg… How big is you tent or grow space? A 4x4?

Indoors… I usually grow 4/tent in a couple of 4x4s… 8 weeks veg maximum… Any longer you will run out of headroom for the plants and your light… Remember you plants can double size during flowering which can take 8-14 weeks depending on strain.

I am assuming your not growing autos.

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