Using a shade cloth for plants helps protect them from harsh sunlight. This might sound like the opposite of what you need, but plenty of plants can get sunburn if they’re exposed to too much light.
Choosing the right shade cloth for plants can get surprisingly complex once you start considering all the different factors. So, here’s everything you need to know about shade cloths.
The name pretty much says it all. A shade cloth is a piece of fabric you use to protect your plants from sunlight. While you could use any fabric you have lying around, proper shade cloths provide varying levels of protection. For example, a standard-weave piece of cotton fabric can block up to 80% of the sun’s UV radiation, which obviously isn’t ideal for a plant.
A shade cloth for plants works by reflecting, blocking or absorbing UV radiation from sunlight. The main purpose is to prevent sunburn and related damage, but it can also change the appearance of your plants.
Plants grown in shadier conditions will typically grow bigger leaves and taller stems. For this to work properly, it’ll need to be a shade-loving plant otherwise you’re just causing etiolation.
We’ll go into this in more detail below when looking at the different factors in choosing a shade cloth, but some situations where you’d use one include:
- In a greenhouse to reduce light and heat exposure
- Over a raised bed to protect crops during the height of summer
- To improve ventilation
- On a south-facing balcony or patio to protect plants from sunburn
The bottom line is that a shade cloth can help protect against heat and sunlight while also improving ventilation and light diffusion. There are some plants listed below that benefit from these environmental factors, but basically any plant that doesn’t enjoy full sun will appreciate a shade cloth.
There are 4 main factors you must consider when choosing a shade cloth for plants. We haven’t listed them in any particular order, but make sure you have an answer for each before making your pick.
This is a pretty obvious place to start. You’ll want your shade cloth to be large enough to cover your plants, although it doesn’t need to reach the ground. Provided there’s sufficient coverage between the plant and the sky, you should be fine.
However, shade cloths are pretty big anyway. For example, this one is 10x20ft., which gives you plenty of fabric to play with. You can always cut a shade cloth down to size if needed, but you’ll want to add a new hem because they fray very easily.
Most shade cloths are made from polyethylene or polypropylene. As you probably know, these are plastic-based fabrics, so they’re ideal for use in all weather. Plus, they’re UV-resistant, which is obviously helpful here.
A shade cloth will either be knitted or woven. Knitted shade cloths have greater variety in terms of color and density, whereas woven is typically denser and often only comes in black and green.
You can expect a woven shade cloth to last 10-12 years, while a knitted one will last 7-10 years. Although it has a shorter lifespan, a knitted shade cloth for plants is more durable because it won’t unravel if there’s a hole. Woven, on the other hand, only has threads running in two directions, meaning it’ll unravel more easily.
For the most part, knitted is a better option because you have more flexibility over density, color, and type. However, in some situations you’ll be limited to woven because you need a denser shade cloth. It’s not a massive difference, but it’s worth bearing in mind.
This is where things start getting a little more technical. The fabric density is measured in percentages, which refer to the weave. By extension, this determines how much light it blocks, in much the same way that sunblock SPF works. Density ranges from 30% to 90% in 5 or 10% increments.
Some examples of plants they work best for are:
- 30% shade cloth: The lowest standard density for shade cloths. It’s best for plants that can tolerate plenty of heat and light, such as peppers, tomatoes and squash.
- 40-50% shade cloth: A mid-range density shade cloth is ideal for flowering plants like lilies, orchids, and begonias. These are plants that would typically live under a leaf canopy in the wild.
- 60% shade cloth: This density is suitable for sensitive food crops like spinach and lettuce that can wilt if exposed to too much heat and light.
- 70% and above shade cloth: The highest densities are suitable for ornamental plants that live on forest floors, such as ferns and philodendron. They need far less light and heat because of where they naturally grow.
Of course, this is by no means an exhaustive list of plants that benefit from shade cloths. The easiest way to tell what density you need is to check a growing guide for your plant in question. Once you have a rough idea of its preferred level of sun exposure, you can choose a shade cloth that’s suitable.
The most common colors for shade cloths are black and green. Black, unsurprisingly, absorbs the most heat and UV radiation, which can be helpful. However, if you need some heat but not much sunlight, a lighter color will be better.
Shade cloths for plants also come in red, white, yellow and blue. Each has different effects on plant growth because they block different wavelengths of visible light. Unless you’re a scientific gardener, this isn’t super relevant.
Some general points include:
- White shade cloths reduce the quantity of sunlight but don’t affect wavelength absorption. This means a plant can grow quicker without risking sun damage. White reflects sunlight rather than absorbing it.
- Green shade cloths are somewhere in the middle, allowing light through but absorbing some wavelengths and heat energy.
- Black shade cloths absorb the most heat and sunlight, which can negatively affect your plants. Choosing a black shade cloth does mean you can use a less dense cloth for this reason.
A 2009 study looked at the impact of shade cloth color on different plants. It found that some plants, such as lettuce and peach trees, grew larger leaves under shade cloths. Lettuce preferred red cloths due to the wavelengths it filtered out. Peaches, on the other hand, weren’t fussy.
The bottom line is that shade cloth color isn’t massively important once you understand the basics of how it affects light exposure. White cloths help retain sunlight quality, whereas black offers more absorption. This is about as complicated as you need to go.
You do need to consider it in relation to density, though. Lighter colors will need a denser weave, whereas a black shade cloth means you could reduce the density by up to 10%.
Ideally, look for shade cloths with grommets (such as this). It makes them much easier to install and reduces the risk of tearing the fabric. You can then fit some poles or hoops to drape the cloth over.
If you need ventilation for your plants – for example, to keep them dry – create an elevated roof using your shade cloth. But if ventilation isn’t as important, hoops are the easiest thing to use.
When shading a greenhouse, it’s easiest to throw the fabric over the roof on the outside. Then, just secure it down with some pegs, and you’re done. Alternatively, you can buy portable greenhouses made from shade cloth fabric, which is the best of both worlds!
It’s entirely possible to make a DIY shade cloth for plants. However, based on the price and availability of actual shade cloths, it’s not super important. If you do want to make a DIY shade cloth for plants, some good options include:
- A white bedsheet
- Window netting
- Nylon netting (for example, that you can buy from a fabric store)
If you’ve got some suitable fabric lying around at home, by all means make a DIY shade cloth for plants. However, be aware that you can’t really determine the fabric density in the same way, which could affect your plants. UV protection from cotton can range from 10-80% depending on the heaviness of the weave.
Generally, if you know you need extra shade for your plants, it’s best to buy an actual shade cloth. It gives you far greater control over the important factors. But if you’re in a rush, a white bedsheet is the best DIY alternative.
You should now have a pretty clear idea of the type of shade cloth you need for your plants. Density is arguably the most important factor because it determines how much light actually reaches your plants. Because most shade cloths are green or black, color shouldn’t take much thought. Either way, you can now enjoy happy, healthy plants!