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Greenhouse Shading, does the colour matter?
Sheps
Posts: 2,236
Morning all...I have been reading up on Internal Greenhouse Shading and I read an article that stated dark coloured shading ( Green and Black ) will actually increase the temperature inside the greenhouse.
So, for those that own a greenhouse, and use dark coloured, internal shading, do you find that this is the case?
I asked this question over on Problem Solving, but only received one reply ( thanks Iain ) so I thought I would ask in this section.
Sheps...
0
Posts
Sheps, it definitely does increase the temperature as dark colours absorbed heat - think black cars left parked in sunshine (what is that????
) and the dark coloured steering wheels and seating in light coloured cars parked in a similar situation.
I originally had green shading in my greenhouse but soon resorted to a paint on shading applied to the outside of the greenhouse. The light colour reflects the sunlight. This can be easily cleaned off in Autumn but does not wash off in rain and enough light can get through so that plants permanently residing in the greenhouse don't get too 'drawn'. I hope this helps Sheps
From a physics point of view, bright colours reflect light, dark colours absorb light.
So whilst a dark colour will absorb more light (i.e. energy) it will become warmer that something light coloured. However for practical purposes, I'd be very surprised if there were any realistic temperature difference so far as the colour of shading goes for a g/h.
I've got light grey blinds on one side of my g/h.
I'd go for personal choice - but avoid black
Billericay - Essex
Knowledge is knowing that a tomato is a fruit.
Wisdom is not putting it in a fruit salad.
Sheps, what ever you use will increase the heat inside after years of green house ownership and many differing attempts at shading I gave up and went for vents instead. My Robinson Lean to Greenhouse built against a South facing wall came with roof vents and a wide door. I took out some grass and fitted louvres putting everything on automatic vent lifters, adding a fan with a thermostat for extra cooling worked a treat. Opening the door and damping the floor down soaking the gravel side bays and leaving a couple of buckets of water under the plants did the job for me and has done for over thirty years. Remember any type of shading reduces light and plants need light, with plenty of through air circulation plus the air movement by a fan on still days you will find the plants thrive just do not water the leaves while it is hot, early morning or late evening is best for that. I say it as I have found what works for me, depending on the position of your greenhouse things may differ, my garden is South Facing maximum sun and heat in the NE of England further south you may need some shading, I once used some old net curtain fixed to bamboo rods in a small house I had at the time, lift it up onto hooks take it down when i got home, it worked.
Frank.
Thanks both... I have found some shading mesh that is beige in colour, so maybe I'll go with that.
I have sourced some guide rollers with fixing brackets, so will have a go at making some blinds once the greenhouse has been erected.
Thanks
Sheps...
Thanks Frank... the greenhouse has 3 roof vents and 2 Louvre vents, so was hoping that would be enough.
Will definitely do the bucket of water idea
Sheps...
Yes the colour makes a difference, but you're relying on the light colour reflecting light back out through the glass. A single pane of clear glass will transmit about 80% of the sunlight energy that hits it, but once it's inside and been even partially absorbed by the blind, the spectrum of the energy changes - more infrared, less visible light comes off the blind than is in sunlight. Most glass is better at reflecting infrared than visible light, so the transmission back out is less good than the transmission in. Greenhouses rely on this to work at all, by the way. So if you put a mirror up as a shade, you'll probably notice quite a big difference to a dark coloured blind, but for most other materials, yes there'll be a difference with paler colours but it's a diminishing benefit.
The best way to keep the heat out is to stop it coming through the glass in the first place, which is why ladybird's external shade is much more effective.
“It's still magic even if you know how it's done.”
I too use the external white shading ('coolglass'. is there another brand?) and just put it in a mister bottle and spray it on. It usually looks quite tidy and removes easily at the end of summer with a soft brush.
My greenhouse is SW facing and does get some shade from trees towards the end of the day so gets less hot than others might.
In my previous wooden greenhouse I used to grow an Eccremocarpus up the glass on the inside at one end, by pinning netting to the roof supports. It revelled in the sunshine, provided shade for the plants below, gave attractive foliage and dangling flowers and could be cut right down at in the autumn, to regrow in the spring. Haven't found an easy way to attach netting in this metal one though..
Last edited: 09 March 2017 07:56:35
What a lovely idea Buttercupdays. Don't your metal greenhouse struts have the channels in them where the special aluminium bolts can be fitted? This is how I fix all my stuff in the greenhouse.
Thanks for the help everyone, it sounds like external shading will do a better job of reducing those high summer temperatures, as well as shade the plants.
Though, I really don't like the thought of having to throw shading over the greenhouse every time it's going to be a hot day, so I am considering making some wooden frames, with the shading sandwiched in between, then I can just pop them up when needed.
Thanks for all the advice, it's greatly appreciated
Sheps...
Last edited: 09 March 2017 09:44:37