Summer heat in Greenhouses - Orchid Board

jenni.stinsons · #1 04-13-2015, 08:02 PM

Hi,

We recently bought nice greenhouse and are already concerned about the summer heat this summer. Greenhouses can sure get hot. My husband doesn't have enough knowledge on the subject, poor hubby.

We bought a greenhouse from CookingFirewood.com and are happy with it but we are thinking of down the road with ventilation or shade cloths and what is really gonna work???

Can anyone help out with advise?

Thanks,

Jenni Stinsons

Daethen · #2 04-13-2015, 10:32 PM

I only have a very small greenhouse and have yet to figure out how to keep it cool. I move all my plants out to the shadehouse for the summer until the night temps get too cool.

The Orchidist · #3 04-13-2015, 11:34 PM

I just spent the day moving my 8by8 greenhouse to a location in my yard beside some bushes that will eventually cover 50% of the sun that may hit the top of it , last year i had reached temps inside of 38 to 40 cel , too much but noticed it was because it was in full sun for at least 9 hrs , hoping this new location will be better , also plan on buying some , screen door screen and cutting out a few panels , and cementing screen over the hole openings in certain spots ,

or i could purchase a misting system , but that could be pricey and than having to run hydro 75 ft to the GH could be an issue . goodluck keepin it cool , last year i ran 3 fans oscillating but heat on some days was quite much , i am hoping this new under shade approach works better

Ray · #4 04-14-2015, 08:49 AM

By my thinking, ventilation is #1. My greenhouse has a screened door panel, which I open manually until nighttime temps moderate, then I leave it open 24/7. That is coupled with two louvered vents (also screened) that open automatically with a "wax motor" opener, to vent out the hot air.

Next is shade cloth (some consider this #1). Definitely go with Aluminet, not a black or green cloth. Aluminet is aluminized mylar, which reflects most of the light; the others provide shade by absorbing it, which converts the energy to heat. You can get custom-sized pieces from gothicarchgreenhouse.com for great prices.

I also have a large exhaust fan, but the passive cooling seems to have eliminated its use in recent years.

Depending upon where you live, some sort of evaporative cooling may be in order.

Believe it or not, general misting, by itself, is of little value in an enclosed greenhouse. Unless there is sufficient air flow through the greenhouse to evaporate the droplets, extracting heat from the air, all misting accomplishes is turning the greenhouse into a steamer.

RosieC · #5 05-09-2015, 04:52 AM

I only have a 6'x6' greenhouse, but I found that a 'must have' was an auto-opening window. If you haven't got one then get one (or more).

In the summer I leave the door open night and day and the auto-opening window is open most of every day letting air flow through the greenhouse (the window is in the roof half way down one side).

In the spring and autumn I close the door at night and sometimes go to work having forgotten to open it. I used to worry all the time if I saw the day had turned unexpectedly warm but the auto-opening window means I worry less, because at least that lets a lot of the heat out.

I agree with Ray that ventilation is the key, and if you have a larger greenhouse you will need more than just leaving the door open as I do.