How hot is too hot?

[WelshGirl]

I think my greenhouse is getting too hot on sunny days - I don't have any plants in there yet this year (amazingly there is still space on my windowledges so far!) but I've been looking at the thermometer and it's getting up to 65 degrees C when the sun is out and it's only April! And that's with the window and door wide open, and of course it's in full sun pretty much all day.
Any suggestions for things I can do to lower the temperature?
Is buying some shading a good idea and what's the best kind to buy?
Any help would be greatly appreciated. I have a feeling my plants will fry if I put them in the greenhouse when it's that hot!

[jackie j]

I didnt buy any shading I just used some thick green netting that I had to hand, it works and I used the greenhouse plastic clips to hold it in place. It will do for now as I already had the netting.
Mine is getting very hot too and is in full sun all day.

[TonyF]

I was in the greenhouse yesterday and it was 102 degrees with the door and (currently) only vent open. No plants in there of course, they're all outside being hardened off.

Mine's sited so it gets partial shade in the morning and the direct sun in the afternoon evening. If your greenhouse is 65, that's pretty good really, it depends on what the weather is like currently where you are, what it's like in the high summer, sun position, that sort of thing.

Shading sounds like a good idea and depending on the size of the greenhouse, you may want to think about an extra vent in the roof and even louvres in the end opposite the door. If you want to really get ahead of the game, invest in the automatic (wax filled cylinder) vent openers, which you can adjust for temperature.

[Two_Sheds]

I have shading on the outside (it's more effective than on the inside) and auto-opening vents, and it's still getting to 30c inside: which means I'm having to water a lot

The school seedlings are in an unzipped plastic blowaway with shade on the top, but they will have been baked to death: the school's been shut for 12 days

[chris]

65C! Mines just tipped 42C and I thought that was hot. I don't have any shading yet, I need to sort some out/look into it.

[Glutton4...]

I use green netting, like JJ, but put it inside with clips (as they are already there). It also has louvres and auto vents for circulation as it is in the sun most of the day, and gets far too warm for me, but I'm a whimp. The floor is slabs and stones, so that gets a good watering in the mornings, which seems to help, too.

[Bren In Pots]

For shading I use net curtains brought from the charity shop, they fasten across the apex on wires seems to work.

[WelshGirl]

Wilkos have pretty cheap greenhouse shading - here - is that worth buying then? I think I've used up all the other net I had lying around so I would have to buy something new anyway.
And I hadn't thought of wetting the floor down... My floor is concrete so I'll have to give that a try! Thanks for the help everyone!

[Dead Dogs]

102 degrees

I assume that's Fahrenheit, otherwise a cup of water would boil.

[BigShot]

102 degrees

I assume that's Fahrenheit, otherwise a cup of water would boil.

...not forgetting the injuries you'd sustain going in to fill the cup of water.


Just remember - we're a confused nation when it comes to metric and imperial.

Celsius to make it sound cold, Fahrenheit to make it sound hot.
Hectares to make it sound small, acres to make it sound big.
...and so on...

[coreopsis]

The highest I got was about 38 degrees C,on a sunny day with all vents and door opened.All tomato/chilli/cuke plants seemed not bothered by the heat-no wilting or scorching.

[Potstubsdustbins]

I have been up to about 35C the last few days so lined the inside with some spare fleece this seems to have help quite a lot.

Colin

[SarzWix]

Apparently above 39c can damage the pollen in tomato flowers and affect fruit-set. I know that probably isn't an issue yet, but best to work out your shading/cooling now, before the flowers start to form...

There's a research article on it, if anyone is interested in the biology: http://dl.dropbox.com/u/11225580/Gen...ruit%20Set.pdf

[FionaH]

Belive it or not Windolene works! Wipes off easy in the autumn too

[Aberdeenplotter]

Any shading is better than no shading. If you are at home when it's hot, splashing water onto the floor of your greenhouse will help reduce the temperature. I wouldn't feel comfortable using windowlene, it's too reminiscent of housework