Sometimes, the plants in your garden need a little break from the heat and light that the sun provides. Shade cloth can provide plants with protection against harsh sunlight during the hottest part of the day in the summer.
So, what is shade cloth? Shade cloth is made from knitted or woven material, such as polyethylene or polyester. Shade cloth filters sunlight and is used to protect plants from sunburn and to keep them cooler. Shade cloth can reduce temperature by 10 degrees Fahrenheit (6 degrees Celsius) or more.
Of course, there are many different types of shade cloth available. The density (or percentage shade reduction) of shade cloth will determine how much light and heat protection it offers.
In this article, we’ll talk about what shade cloth is and what it is used for. We’ll also get into what type of shade cloth to use in different scenarios.
What Is Shade Cloth?
Shade cloth is often used in gardening and farming to increase crop yields in hot climates.
(Shade cloth can also be used to provide shade on a patio to protect people from sunburn, but we’ll stick to the agricultural uses in this article).
When the sun is strong in the height of summer, its rays will raise temperatures by quite a bit. These high temperatures can damage plants by drying out their leaves or burning their fruit.
Shade cloth can help to prevent this damage to plants – but how does it work? Let’s take a closer look to find out.
What Is Shade Cloth Made Of?
According to the Iowa State University Extension:
“Shade cloth is made from knitted polyethylene strands or woven polyester and is water permeable.”https://www.extension.iastate.edu/smallfarms/managing-warm-summer-high-tunnel
The strength of shade cloth depends on the density and material, but overall it is fairly durable. That means it can be used for several years if you use it and care for it properly, so you won’t need to repurchase it every year.
Since shade cloth is meant to provide shade, it needs to be able to stand up to sunlight. According to the University of Massachusetts Amherst:
“woven or knitted shade fabrics from materials such as polypropylene, saran, polyethylene and polyester … are ultra-violet stabilized and have a life of about 10 years.”https://ag.umass.edu/greenhouse-floriculture/fact-sheets/shade-for-cooling-greenhouses
What Is Shade Cloth Used For?
Shade cloth is used to lower temperature by providing shade to plants. This can extend the growing season by a month or longer for certain crops in hot climates.
Shade cloth also protects plant leaves and fruit from sunburn (sunscald) damage. According to the Utah State University Extension, sunburn is common on fruit in areas with:
- Strong solar radiation (intense sunlight without shade)
- High temperatures (hot weather)
- Low relative humidity (dry air)
- High Elevations (hills and mountains)
The University also reports that some fruit was 20 degrees Fahrenheit (11 degrees Celsius) cooler under shade cloth than out in the open sun. In many cases, using shade cloth increased yield and produced higher-quality fruit.
Shade cloth works to reduce both air temperature and fruit surface temperature. For example, shade cloth helps to keep tomatoes cool if the weather becomes too warm for them to ripen naturally.
The ideal temperature for tomatoes to ripen is 70 to 75 degrees Fahrenheit (21 to 24 degrees Celsius), so shade cloth is helpful when temperatures soar into the 80s or 90s Fahrenheit.
Can Plants Grow Under Shade Cloth?
Plants can grow under shade cloth, but they will receive less sunlight (the reduction in sunlight depends on the density – more on this later).
In some cases, you might want to hold off on using shade cloth to give your plants more sunlight during the early stages of growth.
Unless the leaves on your plants are getting burned, wait until you see fruit start to set on tomatoes, and peppers to use shade cloth.
On the other hand, cool-weather crops such as lettuce may need protection early in the season to prevent bolting or bitter leaves.
Of course, there are a few different ways to use shade cloth, depending on how much protection your plants need:
- Horizontal – this method provides sun protection for your plants all day long. However, the cloth has to be mounted high above the plants, or else you will have to duck underneath it to work on your plants (to water, fertilize, pull weeds, and harvest).
- Vertical – this method provides protection only during part of the day. However, you can place the cloth so that it protects plants from the sun’s harshest rays (afternoon sun). Vertical shade cloth can be mounted between rows, and it does not have to be set up as high as a horizontal cover.
You can also wrap shade cloth over an existing greenhouse or high tunnel to provide protection when the sun gets too hot and bright. According to the Iowa State University Extension:
“Shade cloth can lower air temperatures within a high tunnel by as much as 6-9°F.”https://www.extension.iastate.edu/smallfarms/managing-warm-summer-high-tunnel
However, shade cloth can provide even more protection in some cases.
How Much Does Shade Cloth Reduce Temperature?
Shade cloth can reduce temperature by 10 degrees Fahrenheit (6 degrees Celsius) or more. The reduction in temperature will depend on the density (percentage) of the shade cloth and the intensity of the sunlight.
For example, according to the University of Massachusetts Amherst:
“A 50% shade reduced radiation about 10°F.”https://ag.umass.edu/greenhouse-floriculture/fact-sheets/shade-for-cooling-greenhouses
The University also suggests that wetting shade cloth will make it more effective at reducing heat.
The density of shade cloth tells us how thickly woven the material is. The higher the density, the less sunlight will be allowed through.
The percentage of shade cloth tells us how much the sunlight penetration is reduced. So, a 30% shade cloth would reduce sunlight penetration by 30%, so that 70% of sunlight gets through.
A higher density of shade cloth means that a higher percentage reduction in sunlight penetration. Shade cloth comes in percentages ranging from 5% (most sunlight gets through) all the way up to 95% (most sunlight is blocked).
The Utah State University Extension suggests that a 20% to 40% shade cloth is ideal for fruit and vegetable production. A higher percentage could reduce light penetration enough to interfere with the plant’s growth.
What Percentage Shade Cloth Should I Use?
According to C-Mac Industries, the percentage shade cloth you use will depend on what you want to grow:
- Fruits and vegetables (such as tomatoes and peppers) – 20% to 40% shade cloth
- Flowering plants (such as lilies and orchids) – 40% to 50% shade cloth
- Leafy greens (such as lettuce and spinach) – 50% to 60% shade cloth
- Shade loving plants (such as ferns and philodendron) – 60% to 90%
Let’s look at some of the best shade cloth for two common garden favorites: tomatoes and lettuce.
Best Shade Cloth For Tomatoes
In hot climates, tomato plants can produce more fruit with better quality under shade cloth with 20% to 40% sunlight reduction.
According to the University of Nevada at Reno:
“Field trials had New Girl tomatoes yield 78 to 84 percent higher under shade cloth covered hoop houses than the same tomatoes in the field without cover (Gatzke, 2012).”https://extension.unr.edu/healthykids/pub.aspx?PubID=2205
In more temperature climates, a 30% shade cloth works well. According to an experiment by the University of Maryland Extension, using 30% shade cloth increases fruit quality and marketable yield for tomato plants.
You can find knitted 30% shade cloth, such as this 10 foot by 100 foot length, from Johnny’s Selected Seeds.
In hotter climates, a higher percentage shade cloth may be appropriate. For example, the University of Florida has had success growing tomatoes under 45% shade cloth.
You can find a 4 foot by 8 foot 50% shade cloth kit from Gardener’s Supply Company.
Best Shade Cloth For Lettuce
Lettuce is a cool-weather crop, so keeping it a little cooler with shade cloth can result in a better harvest. According to the University of Delaware Extension:
“There is also good evidence that shade cloth reduces bitterness in lettuce, especially when used with a heat tolerant variety.”https://sites.udel.edu/weeklycropupdate/?p=15224
Shade cloth in the range of 30% to 50% is appropriate for protecting lettuce from sunlight. According to Johnny’s Selected Seeds:
“For cold-loving lettuce, spinach and cole crops, use 50% in hot, southern areas, 30% in northern zones.”, such as this 50 foot by 125 foot length from Johnny’s Selected Seeds.https://www.johnnyseeds.com/tools-supplies/row-covers-and-accessories/shade-cloth/knitted-50%25-shade-cloth-20-x-125-9612.html
Just keep in mind that your lettuce may still bolt when its time comes, since lettuce takes its cue for flower and seed production from day and night length.
What Color Shade Cloth Is Best?
White and black are some of the most common shade cloth colors. However, there are also green, red, and reflective aluminum shade cloths available.
White shade cloth reduces heat, but it allows plants to grow faster than green or black shade cloth would. The reason is that white cloth does not completely block any light wavelength, while darker colors (green and black) do block some light wavelengths.
Does Rain Go Through Shade Cloth?
Shade cloth is water permeable, so rain or water from a hose/sprinkler will get through to your plants.
As mentioned earlier, shade cloth becomes more effective when you keep it wet. So, it might not be a bad idea to water your plants from behind the shade cloth.
However, you can always set up a drip irrigation system underneath the shade cloth if you want to keep the material dry.
Now you know what shade cloth is, what it is made of, and what it is used for. You also know what percentages to use for protecting tomatoes and lettuce from sunlight and heat.
There are lots of other ways to protect your plants from summer sun and heat – you can learn more in my article here.
You can learn more about plant netting (or bird netting) which is a little different from row covers, here.
I hope you found this article helpful. If so, please share it with someone who can use the information.
If you want to read some of my most popular posts, check out the “Best of GreenUpSide” page here. Enjoy!