Shade cloth is a mesh fabric made of synthetic fiber designed to block a certain amount of sunlight, anywhere from 20% to 95%. Since shade cloth is a fabric, it allows air flow so the cloth itself can absorb and release heat quickly and whatever is underneath the shade cloth can stay cool. In most cases, it comes in either black or dark green, but occasionally can be white or more rarely metallic aluminum.
In the garden, shade cloth is used for reducing sun exposure to plants either to reduce transpiration and heat stress or to grow plants that prefer partial shade, like irises. In some very hot, sunny climates, you may need to use a shade cloth all season, while some gardeners put them up temporarily during intense heat waves.
Very high percentages of shade cloth can also be used to protect animals and people.
Shade Cloth Percentages
30-50% – Used mainly in the garden to protect tender nursery seedlings, partial-shade-loving plants such as irises, heat-sensitive leafy greens like lettuce, and protect other vegetables that may be stressed during stretches of intense heat and sun (e.g. protecting tomatoes from pollen sterility during a heatwave).
75-80% (and higher) – Used to protect people or animals from the sun, as protection barriers on buildings, and to protect shade-loving plants like orchids.
By How Much Does Shade Cloth Reduce Temperature?
It’s difficult to determine how much of a temperature decrease you can expect from shade cloth, as other factors play an important role, such as humidity and air flow.
For example, 40-50% shade cloth used in a high tunnel or greenhouse with good ventilation and air flow can easily lower temperatures inside by at least 10°F (5.5°C) and possibly more than 15°F (8.3°C). That means if it’s 95°F (35°C) outside, it could be as low as 80°F (26.6°C) inside.
Even if draped over your plants (but not touching them) in a garden bed, you can expect similar results depending on humidity and wind.
What Type of Shade Cloth Should I Use?
The best type of shade cloth will depend on your situation, however, a green (or black) shade cloth of anywhere between 30-50% density will work in most situations. If you need more protection, aim for 50% or even 60%.
Knitted vs. Woven Shade Cloth
Knitted shade cloth is more lightweight and more tear-resistant, while allowing greater air flow. Woven shade cloth is heavier and is less durable (more prone to fraying) but also offers greater UV protection.
Both will serve you well in the garden, but knitted shade cloth is better to keep your plants cool because the cloth itself can dissipate heat more efficiently, and research has shown that higher shade cloth temperature has a lower efficiency at keeping greenhouses cool.
When Should You Use Shade Cloth?
Shade cloth should be used whenever you want to protect your plants from too much sun and keep them cool. It’s conventionally used over a greenhouse or high/low tunnel, but can be used over home garden beds or traditional farm fields.
Gardeners in northern climates rarely need to use shade cloth, but may temporarily use them to protect their vegetables or tender flowers in the height of summer or during extreme heat. In some cases, this can extend the growing season of cool-weather plants like lettuce and spinach which quickly go to seed as temperatures rise.
For southern growers, shade cloth is sometimes a staple in the garden, especially if growing in a greenhouse. In desert climates, shade cloth works extremely well to keep the heat off your plants.
How Do You Use Shade Cloth?
If you have a greenhouse or high/low tunnel, simply drape it over the roof and secure it in accordance with the design of your greenhouse/tunnel. Open windows, doors, or roll up the sides for extra ventilation to multiply the effect of your shade cloth.
In a garden bed or vegetable patch, you have more options. Whatever you do, never lay your shade cloth directly on top of your plants. Shade cloth blocks sunlight but it also absorbs heat, so if you use a green or especially black shade cloth, it shouldn’t touch the leaves or else you may end up burning them and causing your plant to wilt.
Support your shade cloth using any structure, such as stakes, PVC piping, or wires to make hoops over your plants. Secure your shade cloth with tape, wire, or clips.
Related Questions About Shade Cloth
What Color Shade Cloth Is Best?
For most gardeners, green is the best option, followed by black. Black will absorb the most sunlight, but also readily absorb more heat which can make it slightly less efficient. White shade cloth doesn’t have this problem, but is less effective at blocking adequate amounts of sunlight. Reflective metal shade cloth is another excellent option that has the best of both worlds, reflecting energy while not absorbing much heat, however it is more expensive and is mainly used for commercial greenhouses.
Will Shade Cloth Slow the Growth of My Plants?
Plant growth rate is directly related to how much light they get, so in most cases, shaded plants will grow more slowly. However, this growth-light relationship is not linear and some plants won’t necessarily grow faster once they “max out” on sunlight, so shade cloth won’t affect them as much; for example, lettuce does not need as much light to grow at its maximum rate, so you might not notice much of a difference if you use shade cloth in the summer.
Can I Make My Own Shade Cloth?
Yes and no. Any fabric or mesh material that blocks some, but not all, sunlight can be used as a shade cloth. That said, you won’t know for certain what percentage of light you’re blocking. You may be blocking only 10% or 20% light or with very heavy fabric you could be blocking 80% without realizing it. That’s why I always recommend getting shade cloth that is specifically graded to block the percentage of sunlight you need. However, you can still try making your own DIY shade cloth in a pinch.