What Is The Best Way To Shade A Greenhouse?

If you are lucky enough to be a gardener who owns a greenhouse, then between late Spring to early Autumn within the UK you will need to be checking your greenhouse to make sure it doesn’t get too hot. To combat heat one of the options available to the greenhouse gardener is to provide some type of shading. In this article we will look at different ways in which you can add shade to your greenhouse and answer the question ‘What is the best way to shade a greenhouse?’

What Is The Best Way To Shade A Greenhouse? Why Do We Add Shading?   

When we think about adding shading to our greenhouse one of the reasons we do this is to help make the greenhouse cooler – for us to stand and work in, but more importantly for our plants to live and grow in.

We know that the temperature in the shade on a sunny day can be 10 to 15 degrees Celsius lower than if you measure the temperature in full sun and this difference can change a scorching, plant damaging area to a healthy growing environment.

So, what we need to consider is what produces effective shade and is it something we can utilise with our greenhouse.

What Is The Best Way To Shade A Greenhouse? What Types Of Shading Are Available?  

When it comes to options which we can use to provide shade for our greenhouse we can divide it into two main types:

• Material shading – which could be material purchased by the metre, a shade blanket or shade blinds.
• Shade paint – this could be a traditional, permanent shade paint which is like a whitewash – such as Coolglass – or a more modern, weather sensitive paint – such as Nixol - which reacts differently in the hot sun than it does on a wet, damp day.

What Is The Best Way To Shade A Greenhouse? Material Shading     

Shading material can be used on the outside of your greenhouse or the inside of the greenhouse, with pros and cons for either application:

External Shading

• More effective – fitted externally it stops the sunlight passing through the greenhouse glazing and becoming trapped inside.
• Can hinder opening roof vents – if you completely cover your greenhouse it could make it harder for roof vents to open effectively.
• Could be damaged by the weather - the Great British Weather can reduce the life expectancy of materials used on the outside of your greenhouse as they could be damaged by rain or high winds. 
• Harder to fix in place - there are no obvious fixing points on the outside of a greenhouse so you would need to be creative. 

Internal Shading

• Generally easier to attach – with aluminium greenhouses you can usually use standard fixing clips – such as Alliplugs – to hold the material against the frame of the greenhouse.
• Longer life expectancy – as it won’t be damaged by the weather.
• Can be fitted below roof vents – material or blinds can be fitted below opening roof vents so not obstructing ventilation.

There are lots of materials available on the market designed to help you shade your greenhouse, so let’s look at what you should be looking for to ensure the material will be effective.

There are basically two factors which will determine how good the material is at providing shade, these are:

• The Shade Value / Shade Percentage
• The Colour Of The Material.  

What Is The Best Way To Shade A Greenhouse? How Shade Value Works

When you are looking at shading materials one of the features which you should see listed is something called the ‘shade value’ or ‘shade percentage’. This basically refers to how much sunlight will pass through the material, for example if a shade netting has a 40% shade value this will let through more sunlight than a netting with an 80% shade value.

This doesn’t always mean that you should look for shading which has the highest shade value – don’t forget that your plants want some natural light to be able to grow correctly – so it’s a balancing act of providing sufficient shade whilst still allowing in adequate amounts of natural light.

A good example of this ‘balancing act’ is our green shade netting. This has a shade value of 50% achieved by this polythene netting having a lighter construction to enable some light to pass through. We find this level of shade ideal for most domestic greenhouses, as it protects plants from scorching sunlight whilst still allowing them access to good natural light.

What Is The Best Way To Shade A Greenhouse? How Colour Affects Shade Efficiency

Remembering that we shade our greenhouse in order to make our greenhouse cooler, then the effect the colour of the shade material has on temperature reduction can affect how efficient it is.

• White – using a white material will reflect the most sunlight, so is effective in reducing temperatures. You should see a temperature drop of 5 to 8 degrees Celsius under a white shade cloth compared to direct sunlight.
  
  
• Black – black materials absorb some of the heat but provide a uniform shade. You would expect a temperature reduction of approx. 5 degrees Celsius under a black material compared to direct sunlight.
  
  
• Green – you will find green material often used for shade when working with plants. The reason for this is that green reflects some of the green light which plants don’t use for photosynthesis. At the same time, you will see a temperature drop of up to 6 degrees Celsius compared to direct sunlight.

So, when selecting the best material to shade your greenhouse you need to consider both the shade value and the colour together to see how efficient it will be. Also bear in mind how practical it will be for you to install and use.

A good example of a material with a high shade value, dark colour and provided in an easy to install product are the Greenhouse Shade Blinds.

What Is The Best Way To Shade A Greenhouse? Shade Paint
If you choose to use a shade paint on your greenhouse then this is relatively easy to apply – but you will need to be able to safely reach to the ridge of your greenhouse to apply the shading on all the glazing.

Usually shading paint can be applied using a brush or sprayer, but always check the manufacturers recommendations before starting.

One of the other benefits of using a paint on shading – as well as how easy it is to apply – is that it is also a very economical way to shade your greenhouse. Even the more sophisticated shade paints which are weather sensitive – such as Nixol – are still economical. For example, a 1kg tin of Nixol which is sufficient to cover an 8ft x 12ft greenhouse is only £14.99.

One of the things to consider when choosing a shade paint is your greenhouse frame. Most greenhouse frames – aluminium, metal, plastic, resin – won’t be affected by the paint but you might not want to use it if you have greenhouse with an unpainted timber frame where it could mark the timber.

Top Tip
If you are using a traditional shading paint – such as Coolglass – then it is important that at the end of summer when temperatures fall and days are not as sunny, that you spend some time removing the paint from the outside of your greenhouse. This then allows your plants to gain maximum benefit from the natural light through the rest of the year.

What Is The Best Way To Shade A Greenhouse? Is Shading Your Greenhouse Sufficient?

So, at the start of this article we explained that one of the reasons for shading a greenhouse is to help to make your greenhouse cooler. But you need to be aware of the need for your plants to have sufficient natural light for healthy growth – for example, tomatoes grown in a greenhouse thrive on as much light as possible, as do many edible crops which you might grow in your greenhouse.

So, shading is a fine balancing act of using the minimum amount to help keep your greenhouse below damaging temperatures of over 27 degrees Celsius, whilst not blocking out too much natural light that your plants struggle to grow.

This is one of the reasons that when cooling your greenhouse, shading should be used at the same time as ventilation and humidity – it is only the combination of all of these which will be successful in reducing the temperature within your greenhouse.  

Our blog post What Is The Best Way To Shade A Greenhouse? has been created from our personal knowledge, information gathered by speaking to other gardeners or manufacturers in the gardening industry, by reading gardening magazines and devouring information from books and the internet. We aim to be as accurate as we can, so if you find a mistake, please remember, we’re only human. if you have any queries you can contact us today!