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Roger de Jagher
Specialist Shading and Coating | 20 May 2022 | 4 min. reading time

Shading reflects light and lowers the temperature in the greenhouse. As a result, less evaporation within the crop occurs, preventing the plant from drying out and hanging loosely. It can be stated; the shading improves the climate in the greenhouse. Eventually, this leads to less stress for the crop and a better result. There are various types of shading that you can use. Well known are:

• Shading agents and coatings
• Shading screens
• Shading nets

The roof-ridge is very important in greenhouse shading, as this part of the greenhouse gets the most sun, from morning to evening. Wear marks on the ridge are therefore very detrimental to the crop and should be minimized. The ridge of the roof is also affected by rain, hail and wind and it is therefore crucial that the ridge is properly covered.  For this, you can use a high-quality greenhouse shading product which is wear-resistant. It is also possible to chalk (meaning: apply greenhouse shading paint) several times with a relatively cheaper product, which is less wear resistant. It is recommended to always ask for advice when choosing a specific product. 

The percentage of screening indicates the effect that the shading has on solar radiation. This allows you to compare screen products before you make a choice.

Many automated systems react to brightness in the greenhouse. Think for example about the closing of a shading screen. With the influence that the brightness has, it is useful to know how much light a particular (screen) agent reflects.

The gross shading rate is shown on the packaging of a shading agent, but there are more elements that influence the brightness in greenhouses. These include:

• A coating
• Specific glass
• Window sizes

Together this is called the gross screening percentage. If you are talking about the contribution of one specific product to the incidence of light, then you are talking about net shading. Therefore, it is important to know whether the percentage on the packaging refers to the gross or net shading rate.

Most growers apply shading paint using a machine like the Top Cleaner. This guarantees a correct application of the product, in the right quantity. If you choose to spray coatings fully automatic, no one has to ride along an no one can fall. It is a safe way of applying greenhouse shading paint. With a small expansion, the machine can also be used to apply a layer of chalk or coating. We can also deliver rails and a movement platform if desired.

Diffusion coatings ensure that the light in the greenhouse is better distributed, both horizontally and vertically. As a result, there are no longer any light or dark areas. The advantage is that the crop experiences less stress and grows better. In addition, the light penetrates deeper into the crop. This increase in light makes the leaves much more active further down the crop.

The difference between shading agents and diffuse coatings is that shading agents provide reflection and diffuse coatings provide transmission. So shading agents help you reduce greenhouse temperatures by reflecting light. Diffuse coatings scatter sunlight over a larger area and thus simultaneously "distribute" radiant energy over a larger surface.

	Shading agent	Diffuse coating
Reflects excessive sunlight through shading
Prevents shadow formation through light diffusion
Reduces greenhouse temperature
Reduces plant temperature
Becomes transparent when wet	*
Adjustable shading percentage
Ensures an even temperature distribution in the crop

* Only Temperzon T74 has this property

By highly diffusing incoming sunlight up to three times more valuable photosynthetically active radiation (PAR) will reach the middle a bottom parts of the crop and eliminates shadow formation of the greenhouse construction. All this ensures a higher reception of light in the greenhouse which in turn leads to more and better growth of crop and fruit. In floriculture diffused light has proven to lead to more growth and in the cultivation of vegetable crops it has shown to increase production and at the same time improve fruit quality. In the video below, the effect of diffuse light is explained.

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