Keeping Polytunnel Cool - Ideas?

[Susan BBPM]

I live in the West of Scotland. Up here it's rare that you have more than the odd day in summer when temperatures get dangerously high in the polytunnel. But this year we're being blasted with wall to wall sunshine and high temps day after day. I rarely get the tunnel below 30 degrees during the day, and even with shadecloth, regular hosing down with cold water and a fan blowing fresh air through the door I'm still creeping up to 40 degrees C regularly thoughout the day. All doors and vents are of course wide open.

The tunnel is positioned so that it is in full shade from around 4 oclock onwards, and partial shade from around 2pm. It's 3pm now and despite all my efforts it's reading 39 degrees.

Everything looks fine still - tomatoes, peppers, melons, cucumbers.

Would appreciate advice from those in warmer climates.

 

[big rockpile]

Sounds like you are doing all you can. Good Luck!

You might consider putting racks outside to set your plants on until Greenhouse is needed again.

big rockpile

 

[Susan BBPM]

Unfortunately most are in beds inside the tunnel. But I do have some peppers in pots - it hadn't crossed my mind to move them outside when it's very hot. Will do that tomorrow.

This afternoon I made a 'porch' out of shade cloth - this keeps the sun from shining through the door in the afternoons. Later in the season I'll have a wall of Greek Gigantis beans shading the door - that will serve a similar purpose, but for now that shade cloth porch is helping a lot.

 

[big rockpile]

I kind of have same problem I need to get more Thermometers I can trust. I had two 6 degrees different. Which to believe? LOL

big rockpile

 

[DirtMechanic]

So here it can go that high but with humidity. Wet bulb thermometers help track transpiration inhibiting temps best. It is not enough to just use a shade cloth because here the re-radiation of heat can be a problem. Some people solve that by moving the shade cloth or top skin out onto spacers allowing a cooling space of significant size. Allthread rod and big washers work pretty well for this.