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Upa Creek, MO

We are having record heat here today getting up to 107 and staying above the 100’s for at least the next 10 days. But, it is a very dry heat and not as bad as a 95 degree day with high humidity. With dry heat, temps are also able to cool much faster at night into the upper 70’s. Even by late evening, it is comfortable.

My question is dry heat at very high temps or high humidity heat at lower temps better for plants? Do the leaves benefit from high humidity and moisture in the air even though indexes are much higher, or do you think they benefit from cooler nights that come with hot dry weather?

For me, I don’t mind working in this +100 with little humidity weather compared to 90’s and humid, but I am not a pumpkin plant last time I looked in the mirror.

Thanks

6/28/2012 9:43:33 AM

Little-TON - Colorado

With the amount of water I have had to put down to keep em from burning...I think the humidity is high at their level. Ground iZ soaked....I gotta watch about too much water... Now when the wind started...you could see the leaveZ just melt aZ water went else where....I dont mind working in it either..but it doeZ sure drain a person too.....stay thirZty my friend.....

6/28/2012 9:56:20 AM

Nottingham, UK

Today we have thundery showers, zero sunshine, darkk sky and humidity is 95%. Its very opressive and I would rather go for dry heat. Like you, wouldn't mind knowing what the plants prefer.

With increased humidity would there be less water lost by the plant by transpiration? Would that be a benefit? I'm sure someone who knows more about plant biology will tune in with the pro's and con's of both.

6/28/2012 10:14:56 AM

Pataskala,OH

Humidity is a good thing, if it is not humid you get highs in the 80s and lows in the 40s or 50s for example. If it is humid it will be in the 80s in the day and in the mid 60s at night for example. I think big temperature changes are not good for any plant.

6/28/2012 10:24:07 AM

milford, CT,

Doesn't high humidity prevent evaporative cooling more?

6/28/2012 4:39:42 PM

nOVA sCOTIA

This is an exellent question and i for one would love to learn more on this subject.

6/28/2012 4:50:35 PM

Upa Creek, MO

Or I could rephrase what is better deep south, Georgia swamp style heat at 95 degrees\high humidity or Arizona desert sizzlers at 110 and almost zero humidity?

We are at 107 as I type this but only 14% humidity so really doesn't feel that bad. I see Milford's point about evaporative cooling which is why we are miserable in high humidity? Is there a botanist on board?

6/28/2012 5:13:39 PM

Little-TON - Colorado

http://www.jasons-indoor-guide-to-organic-and-hydroponics-gardening.com/plant-growth-and-humidity.html

Nice lil article on the subject...enjoy

6/28/2012 5:21:02 PM

Little-TON - Colorado

Time for CO2 as well..

6/28/2012 5:23:16 PM

Mass

I believe after 76 degrees or was it 86 degrees ? from Niagara seminar 2 years ago, Photosynthesis stops. Id have to go look at some old notes. I FOUND IT (86 degrees). So I dont know if any of this heat helps. Best growth between 68-86.. 77 is the lucky number. I dont know about the humidity.

6/28/2012 6:08:37 PM

Colorado

its 86 degrees -when the plants stop phot. and start to respire.My guess is youll have more burning from higher uv with the less humidity but the plants will be under less disease threat with the nights cooling off more.

6/28/2012 6:20:18 PM

North Smithfield, RI

Doesn't high humidity promote disease ?

6/28/2012 7:09:03 PM

Upa Creek, MO

Thanks for the link Wiz, and replies everyone else.

6/29/2012 10:45:25 AM

Hinckley MN

my 2 cents is that leaf temperature is more important than air temperature. at 90 degrees, in full sun, a dark green solar collector (AKA a leaf) can be much hotter. it is the same principal as frying an egg on asphalt. The leaves can transpire to cool themselves but that takes large ammounts of water. shade cloth and misting or overhead watering can also reduce leaf temperatures. if the leaves are drooping, they are in survival mode and not photosythetic mode and are not feeding the plant.

6/29/2012 10:17:18 PM