Is greenhouse shading necessary?

Rob45

Hi All,

I live in south Scotland and wonder if it’s necessary to put up greenhouse shading this summer? I’m growing tomatoes, cucumbers, peppers, chillis and aubergines. The greenhouse has an auto vent plus another opening window. It can get hot but auto vent usually stays on top of that.

Any advice gratefully received.

Rob 

Hostafan1

It depends on a lot of factors. Site, temperature, natural shade etc. The size of the greenhouse has an effect on how hot it gets/ how fast it heats up and cools down.
Heat per sé isn't always the problem, it's dehydration. If the plants are well watered and the air is humid, they should be fine. 
Every garden is different so you'd really have to just keep an eye on things and see if things are starting to suffer.

Rob45

Great, thanks for reply. Our plants are always well watered. Tomatoes in watering system, potted ones will soon be in trays. Cucumbers in grow bags - still getting to grips with amounts for them but they’re never dry. Greenhouse is 6 x 10, gets full sun most of the time. 

Hostafan1

I think the problem might be the size, heating up very quickly and cooling down very quickly. 
"Suck it and see" 
good luck with the crops.

Allotment Boy

You can always go for partial shading. I.E. if you use shade paint then only do alternate panels of glass, or do one line  between the bars or with netting again cut to size of one "run" of glass & fit it to the glazing bars.  Then leave the next one clear etc. The other thing would be if the sun is mainly just from one direction then just shade one side not the other. This will reduce the fiercest heat of the Sun without blocking too much light and making plants "drawn". 
Hope this makes sense.

Palaisglide

Rob, my greenhouse is a wall mounted south facing and I never shade here in the NE, Durham. When I built it I bought extra Louvre openers as well as the auto openers and made sure I got a through draught. The prevailing wind is either east or west so we always had some breeze.
The Tomato side was dug out lined with plastic then filled with gravel, the tomato's go in twelve inch pots on that gravel which is always damp. I half fill the pots to start then top up with compost every ten days or so until full, that feeds the plants. when I finish with the pots and clean up the Tap Roots are always down into the gravel. When all around lost plants to blight I did not.
Each morning opening vents and the door as needed will give a reasonable control of the heat, the back brick wall takes in the heat during the day and gives it back at night when I close the greenhouse apart from leaving the louvres slightly open for some airflow. It has worked for 35 years and never once have I shaded.
Frank.

mwtbones

I'd say the only way to know is to get a greenhouse thermometer (you can get transmitter based indoor/outdoor temp and humidity models for a tenner). I've seen people reporting temperatures in their greenhouses being regularly upward of 50C in mid-summer, which I think would be enough to warrant shading or forced ventilation for me.

Palaisglide

Forgot to mention my Daughter bought me a fan with a thermostat around 30 years back still going strong it moves the air through the green house. H&S may have something to say about it, as long as they do not look ion my Garage.
If Rob and I lived south of the Humber we may have to look at some shading, our weather is more moderate.
Frank.

Yviestevie

I shade the side of the greenhouse that gets the sun at the hottest part of the day.  It helps prevent the leaves scorching on really hot day.