The trick to knowing which shade cloth to buy is simply to know how much sun your plants need. Are you growing tomatoes, tropical houseplants, orchids, or herbs? You’ll want to choose shade cloth density based on what you want to grow.
You may be wondering if you need shade cloth if your greenhouse is already in shade or partial shade.
Like the answer to many gardening questions, the answer is…it depends…and you may want to experiment.
The ultimate goal here is to control how much sun your greenhouse is getting, whether that’s by it’s location or by using shade cloth. And how much sun you want your greenhouse to get will depend on what you want to grow.
Shade from trees or a building will block light from reaching the plants. Shade cloth will filter sunlight to let a certain percentage through.
This brings us back to fabric density. This refers to how loosely or tightly the fabric threads are woven, which directly affects how much sun gets through. Products labeled as garden shade cloth are either knit or woven. Knit shade cloth is made from polyethylene and it has more loosely woven threads and it can be cut it to size without it unraveling. This means it’s more lightweight and easier to work with. Woven shade is made from polypropylene. Its threads are tightly woven together and it’s a bit heavier, but it offers more UV protection than knit shade cloth. It will unravel if it is cut or gets a hole.
Now, back to some other considerations when choosing shade cloth. You might be wondering if dark colors or light colors are better.
it’s important to remember that if you’re using greenhouse plastic on your greenhouse, it protects from UV rays.
White shade cloth reflects sunlight and heat. It keeps a greenhouse cooler, but it only diffuses light and so lets the full light spectrum in, including harmful UV rays. You might want light shade cloth if you live in a hot climate and you’re constantly trying to protect your plants from too much sun and heat.
Black shade cloth absorbs sunlight and heat. It makes a greenhouse hotter, but It filters light and offers protection against harmful UV rays. You might want dark shade cloth if you live in a cooler climate and want to keep as much heat in as possible. Or you might want dark shade cloth if you’re using it out in the garden without the protection of greenhouse plastic; as an added benefit, it will blend in to the landscape better than white shade cloth.
Are the differences significant or negligible? It’s hard to say. It will depend on your climate, your goals, and your aesthetic preferences. For me, black shade cloth wouldn’t help me much in the winter because my greenhouse doesn’t get much sun during that time of the year (it’s on the north side of my house and I live in a cloudy area). In addition, I don’t try to grow during the winter, so I’m only concerned about the other seasons.
This post wouldn’t be complete if I didn’t mention one other idea. And that is to place the shade cloth over the top of the greenhouse, on the exterior. The benefit is that the cloth absorbs or reflects the light and heat before they even enter the greenhouse. Again, is it significant or is it negligible? I haven’t done it so I can’t say. But some folks do place it on the outside and then fasten it down.
If all this information has got you feeling a little heady, just remember this: shade cloth in a greenhouse is usually necessary, and many, many plants do just fine with 40%-50%. If your greenhouse is dedicated to growing something specialized then you may want to consider a different option, but for many of us this will be a good solution.
And don’t forget about other little tweaks you can do in the greenhouse. Move light-sensitive plants under a table or behind a larger plant. Place shade cloth on the sides and leave the top unshaded. Or shade one side and leave the other side unshaded. The more time you spend out there, the more in-tune you'll be with where the sun is hitting and what plants need shaded. Observe, and your plants will tell you what they need. If you are interested in our products, please contact us: firstname.lastname@example.org