Tomatoville® Gardening Forums

Tomatoville® Gardening Forums (
-   Undercover Gardening™ (
-   -   How can I reduce heat inside greenhouse. (

49tandc June 25, 2017 10:45 AM

How can I reduce heat inside greenhouse.
I do not have electricity (except 12V. solar) in the greenhouse. Standard temps from late May thru Sept is mid 90s here in North Florida. Greenhouse goes over 100 most of the afternoon)

I'm considering running misters on a timer (a 12V solution); Getting a couple of 12V fans from the junkyard (another 12 V that would require another battery/solar panel, etc). or getting a couple of "wind turbines and cutting holes in the plastic to let the heat out.

Do any of you guys or girls have experiences with these methods, or perhaps have a better solution? I'm all ears...


Worth1 June 25, 2017 10:58 AM

Vent/open the bottom and vent/open the tops all the way down.
No I dont have a green house myself but it is the only way you will be able to dump the hot air out without power.


Nematode June 25, 2017 11:41 AM

Spray the white stuff on the plastic to cut the heat load.
I think its a clay.
Open it as much as possible. Cut it if you have to in a way thats patchable.

49tandc June 25, 2017 04:37 PM

Both ends of the greenhouse are open, and the side plastic is rolled up for the summertime Just the top is covered in plastic, but its still VERY hot in there. My tomato production is way down. Flowering, but not producing little toms.


mjc June 25, 2017 04:55 PM

Shade cloth.

What style of house?

What's the spacing on supports? Could you possibly stretch a piece of plywood across somewhat close to the top to mount the turbine type exhaust fan?

Increasing the humidity with the misters will probably make things worse...clumping of what little pollen the heat hasn't fry and increase the chances of fungus problems.

Nematode June 25, 2017 04:56 PM

Ok only other thing I can find is this:

Pricey though....

mjc June 25, 2017 07:40 PM

I'd be very tempted to go with this...

It will cut down quite a bit of sun. No, it's not quite as sturdy, but it will work (there is 'denser' stuff, check the various offerings).

49tandc June 25, 2017 08:40 PM

The house is 12 wide X 40 long X 8 ft tall hoop house, with 16 ft cattle panels making the hoop. The shade cloth is laid over the panels and plastic over the shade cloth. I have a steel pipe running down the middle at the peak which supports the tomatoes (on string). It has withstood a couple of very strong topical storms already, but there is no other bracing in the house.


Cole_Robbie June 25, 2017 10:07 PM

I used to throw mud on mine, before I finally bought some shade cloth.

bower June 26, 2017 10:30 AM

Short of cutting holes in it, it sounds like fans must be the answer... you already have vented the sides and are using shade cloth, but the top is still trapping heat. The ends should be vented right to the top, and install your fan up there to blow fresh air through the top so heat isn't trapped.

Being in Florida, a solar powered fan would be the obvious solution to no electric on site.:yes::)

My Foot Smells June 26, 2017 12:18 PM

hmmmm..... if your outside temp is 90 and your gh only gets to a hundy, that's not too shabby. my gh is storage during may-October, as it can get 180 up in there on a 90 degree day - and that is with cross ventilation (door wide open & 2'x2' window open).

I have a fan and 120v, but pffffffftttt doesn't seem to help much. shade cloth does help - some - but probably need something from nasa if gets west sun. NoFlo can be brutal despite the "north" being in the name & sticky too.

a pic would be helpful, but have to ask why you are in the gh anyways, unless you plan on running some ac up in there.

Black Krim January 26, 2018 09:17 PM

At 4:37 is a mechanical vent. Need to be set into a frame though.

BigVanVader January 26, 2018 11:11 PM

1 Attachment(s)
50% shade cloth is what all the growers here use.

I only needed it for 1 side so for 20 bucks I dropped my temps inside 20 degrees

Cole_Robbie January 27, 2018 02:31 PM

My stuff is the "aluminet," 45%. It looks like a silver foil mesh.

clkeiper January 27, 2018 03:56 PM

I use aluminet. too. it really does work better. we wiggle wire it right to the high tunnel. sell your tomatoes to pay for the stuff if it is too costly to pay for out of pocket. if you go more than 50% shade you will get NO tomatoes. they won't blossom. the screening from lowes... does it tell what the percentage is? if not I wouldn't take my chances on trying it.

All times are GMT -4. The time now is 04:06 PM.

★ Tomatoville® is a registered trademark of Commerce Holdings, LLC ★ All Content ©2017 Commerce Holdings, LLC ★