shade Shade Cloth

seussiii · Apr 8, 2017

Been scouring through google and have come across multiple answers on this...

The big question! Does shade cloth cut down usable light?

I've read that it will reduce the UV (damaging portion) from light and reduce heat by ~10 deg but the plant still receives the full spectrum of light as if it were in full sun. In other words if you have a plant in 6-8 hours of full sun and you put it under 50% shade cloth it will still benefit from full sun and not partial shade due to the diffused light.

I've also read the opposite. That it will simply diffuse the light and temp leaving that same 6-8 direct light plant with the results of plant grown in 3-4 hours of direct sun.

Thoughts?

I don't plan on testing this on my peppers but on some heat tolerant greens.

CAPCOM · Apr 8, 2017

Fear not, I have used a shade cloth for the past 2 years and would not think of hardening of my pepper plants with out one. I diffuses light while still allowing some of the uv in, just not the harmful dose in direct sun.

Hammerhead · Apr 8, 2017

I'm in central Fl. also and have been using 50% shade cloth for the last 4 years. Can't imagine plants surviving without it. These summers are brutal on the plants and they get that "wilted" look even under the shade cloth, go for it!!!

solid7 · Apr 8, 2017

seussiii said:
Been scouring through google and have come across multiple answers on this...

The big question! Does shade cloth cut down usable light?

I've read that it will reduce the UV (damaging portion) from light and reduce heat by ~10 deg but the plant still receives the full spectrum of light as if it were in full sun. In other words if you have a plant in 6-8 hours of full sun and you put it under 50% shade cloth it will still benefit from full sun and not partial shade due to the diffused light.

I've also read the opposite. That it will simply diffuse the light and temp leaving that same 6-8 direct light plant with the results of plant grown in 3-4 hours of direct sun.

Thoughts?

I don't plan on testing this on my peppers but on some heat tolerant greens.

There are very few varieties of peppers that need shade - many are native to equatorial regions, after all, which receive more UV and lumens than any other area on earth. Some exceptions to the rule would be Rocotos. I just started growing them out this year, and when they go full sun, they shut down. Put them in shade, and back in business. But any Chinense, Anuum, Baccatum, etc - give them full sun. If you're hardening off, that's different. But literally none of the varieties that I mentioned up above, can't handle full sun. I have a yard full of peppers that take the full force of the sun, as each season gives it.
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I don't know the exact science of UV, but I have never understood it to be the case that we have sufficient UV to damage plant tissues, other than the fruit. (or maybe that hole in the ozone layer they always talk about has parked over Florida)
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I'm not sure that I'd agree that shade cloth retains the full spectrum of sunlight, either. There are different colors for a good reason. And that reference to the amount of light time length... I don't buy it. I don't think that there is a proportional relationship between intensity and exposure equivalence. Even if intensity is reduced, I don't believe that it necessarily means that you are going to see a result as you've described. Different plants seem to have wildly different thresholds for lighting. (range of what they use with similar results)
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The real danger with shade cloth and plants, is reducing air circulation - especially when humidity is high. Be sure not to fully enclose your growing area. Resist the urge to use shade cloth as bug netting. It reduces air movement by more than the amount that it reduces light penetration.

CAPCOM · Apr 9, 2017

For what its worth, the two weeks my plants are confined to the sun screen they do not appear to suffer from lack of circulation at any degree. I have been in the tent working while a breeze was present and found the screen to provide a refreshing retreat from the mid days sun.
Mind you, after hardening off, all the plants go into the full sun where they respond very nicely thereafter.

pecker88 · Apr 9, 2017

I covered a small area inside my greenhouse with 40% shade cloth for hardening off my peppers and tomatoes. Yest. I moved them to full sun for about 4 hrs, today I'll increase that to 6 hours then take the shade cloth down tomorrow.

This is the first yr. I've used shade cloth for hardening off and its working great. On June 1st I put the shade cloth over the entire greenhouse on the outside to help with the scorching temps inside. Last yr. all the peppers produced tons of pods with the shade cloth on from June 1st to Sept 1st.

seussiii · Apr 9, 2017

Yea i have a partial shade area that I use for hardening off but this would be a potential project for a caterpillar tunnel. Rather than plastic I would use 50% shade cloth for the reduced temps and bug protection.

I read about the potential air flow issues but as long as I have a decent volume of air below it and enough space between the plants and the cloth it should be good.

This application would be for kale, lettuce, maybe tomatoes. Some have mentioned that it will keep heat tolerant greens from bolting as fast. I guess I will have to test.

My main concern is how being under a 50% shade cloth in full sun would affect any crop yield. If at all. These crops would grow full cycle under the cloth.

solid7 · Apr 9, 2017

seussiii said:
Yea i have a partial shade area that I use for hardening off but this would be a potential project for a caterpillar tunnel. Rather than plastic I would use 50% shade cloth for the reduced temps and bug protection.

I read about the potential air flow issues but as long as I have a decent volume of air below it and enough space between the plants and the cloth it should be good.

This application would be for kale, lettuce, maybe tomatoes. Some have mentioned that it will keep heat tolerant greens from bolting as fast. I guess I will have to test.

My main concern is how being under a 50% shade cloth in full sun would affect any crop yield. If at all. These crops would grow full cycle under the cloth.

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Lettuce isn't go to work here. That's a cool season crop. It will harden and bolt, even under shade cloth. I've not seen anyone have any success past May.
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So, when we set up the shade houses in the nursery, there are always openings. Some have angled walls (made with shade cloth) and open doors, and some are just canopy. But either way, we NEVER close them off. Part of that is because the air will be used quickly inside, if you have any number of plants. But also, because the air movement is greatly restricted. To design a shade house properly, and keep mechanical air movement to a minimum, you'd want a wide open space, with direct wind exposure.
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Of course, tomatoes are grown in Florida all year in hothouses. (shade cloth tents) But, I think you'll find that even at that, you'll need to select heat resistant varieties. The heat combined with the constantly high humidity is what really prevents good production. I was born and raised in Nebraska, and even though our temps were often over 100 degrees, we had a garden full of tomatoes every season, with no shade cloth. However, maybe due to the soil composition, or some other factor here, we just can't get tomatoes to do summer - even when temp and humidity conditions are similar. I don't want to discourage you - but you'll need to temper your expectations. Some of the most successful summer tomato crops here, are also some of the most bland varieties.