shade Shade cloth - Yes/no?

T

ThePickler

Howdy,
 
Please correct me if I'm wrong, but I was reading that pepper plants won't set pods if it gets too hot during the day.  Is it worth investing in a shade cloth (even one that reduces UV by 30%) to try and keep the plants a little bit cooler?  Our summers are short, but they can get pretty hot with a lot of sun.  Even if the plants are supposed to have come from typically hot places, they seem quite temperamental.  They were doing great in the greenhouse but seem to be getting torched/beat to snot outside. 
 
Who else uses shade cloth?  What has been your experience?
 
Thanks
 
Two things to consider.
 
1.  Hardening Off/Adjusting.  Did you ease them into the outdoor sun or just put them out into the direct sun? Plants need time to adjust in dappled sunlight, shade during the heat of the day, etc. Generally 7-10 days as a rule of thumb, but it can take even longer. The tissue they produce in less intense environmental conditions isn't capable of dealing without a more gradual adjustment, creating a risk considerable burn damage to your plants. They need time to develop their tissues to accommodate the more intense conditions. Shade cloth can help greatly.
 
2. Growth and Heat Sterility Once Adjusted.  Burning damage to plants that have been given time to properly adjust to strong sun and heat is unlikely.  However, once they're adjusted, high heat might prevent them from setting pods. Even higher heat might result in sub-optimal growth. Shade cloth will help if you're marginally into these limiting ranges. Also, different varieties have different range tolerances, e.g., rocotos may shut down production when chinense are loving the heat and setting pods copiously.  As an example of using shade cloth, if you have peppers that have been hardened off, but won't set pods because it's slightly too hot, shade cloth may bring them back into an acceptable range. If it's way too hot, more likely not. If it's too hot/sunny for them to grown well, then it can certainly help.
 
Thanks for the reply CaneDog.
 
The peppers lived in the greenhouse for two weeks before going outside.  They spent a week with screens, shading them a little, and a week without them (only glass between them and the sun).  It didn't get very cold inside the greenhouse (maybe down to 50F) but I figured they would be OK, given the length of time they were there.  I had a gusty fan on them from the time they were seedlings of maybe 2-3 inches in height.  We did have a few nights of COLD evenings, into the high 30's.  We also had some days with HIGH winds (gusts to 25MPH).  I didn't have the cloth to cover them so I had to cross my fingers. 
 
Here's what I have:
 
Most of the plants seem OK.  My Thai's, Jalapenos, etc are doing well.  The superhot's are dropping leaves like crazy, however there is a lot of new, deep-green growth under their failing canopy's.  So maybe they're alright but will just need to regrow their foliage?  A few of the Douglah's are getting by, but I winge a little each day I go out and see more leaves on the ground.
 
Sound like a hardening issue?
 
This is why I'm starting more superhots to just grow indoors. 
 
Thanks.
 
You bet pickler!  Yeah, it sounds like a hardening issue. The leaf drop with new green growth is pretty textbook and the healthy green new growth is good news. It'll just slow them down some.  They should still have lots of energy to rebound. I had a harder time than usual hardening off plants this year. The weather just wasn't cooperative.  Despite (attempted) progressive exposure for weeks, many still suffered during early hot spells, but they've adjusted now.
 
My feeling is once adjusted, your plants should be fine in Montana heat - though when temps are peaking it may interrupt fruit set. You're probably getting what during summer, a lot of 90's and some triple digits? There's probably people in hotter areas than mine who can talk specifics with you on the shade cloth, but I feel confident it's a hardening issue and they'll rebound.  Sometimes nature just makes it tough despite doing the right things. 
 
Thanks for the replies everyone.  We're having some cold weather again where we're at (snow up high in the mountains, rain down low and quite a bit of wind again yesterday), so a lot of the garden is struggling.  It's reassuring to hear that they'll most likely rebound, they were looking great before heading outside, then all this happens.  I remind myself that there's another three months or so of grow time and Mother Nature should be turning the switch to "Summer" here soon.  Hopefully, hehe.
 
It's highly unlikely that you need shade cloth in Montana.  A lot of us nearer the equator need it due the high UV intensity, which is absorbed by everything.  Pots, soil, plant, etc.  The high temps aren't necessarily what is detrimental.  It's the temperature of everything else that is in the vicinity of the plant.  This effect is even worse when you add high humidity to the equation.  When it's 91 degrees outside, with a "feels like" temperature of 104, and the humidity is >85%, that's shade cloth territory.
.
I just looked up Missoula, MT, for grins.  It says the max UV index for the week is 8.4, with an average of something closer to 4.1.  That's a wild swing.  By contrast, in my area, the low index for the week is 9.1, and right now, it's 11.5.  The average on the week is 10.5+.
 
Here in south-central Pennsylvania, I used a 30% (allowing 70% light) shade cloth on peppers at some point during the growing season the last 5 years in a community garden. Specifically, to protect fruit from sunscald, which was a REAL issue. Come August, it will either be raining cats and dogs or it will be 95°F and we won't see a drop of rain. The gardens were located on a rise and there was non-stop wind/breeze, so any shade offered by leaves didn't help much.

When not shading the peppers, I used it to extend the growing season of cool weather crops like lettuces and to offer protection to cool weather crops planted mid to late summer for fall harvest, along with helping to keep plants such as cilantro from bolting. It would always amaze me how much cooler it would be under it.

I say, be prepared.

20190621_133836.jpg
 
My two cents is they weren't UV hardened gradually enough. That glass you mentioned - I am GUESSING, was blocking UV. Most glass does.
 
I would agree with you John.  Alot of them had tons of new growth come out of their stems.  That stuff looks great, the canopy's look rough but are coming around.  The gardener who moved his plants into the greenhouse two weeks before I did has had no issues with his plants.  This was probably the case. 
 
Any thoughts on this:  plants take more time to harden off the longer they've been under grow lights? 
 
Some experienced folks are probably smacking their foreheads saying: "NO $HIT SHERLOCK!" because they already know the answer.
 
Thanks
 
Depends on what kind of lights.  I've got a couple lights that have almost dangerous levels of UV. (not all lights have a useable UV spectrum)  There's no real issue with hardening off, even under Florida sun.  It's a pretty straightforward affair.  First couple of days, only indirect light, day 3 and 4 get evening hours, day 5 and 6 get morning and evening, and after that, they're pretty much ready for the big show.
 
Mind you, that's just my experience.  If some people say it takes longer because of the lights, I'm looking first at the UV component.  I'm not sure that it actually does.  
 
Last year I used shade cloth over a bed of Numex Joe E. Parkers. Not superhots, nor greenhouse grown. I grow a bed of these every year. And using shade cloth for the first time my plants were the best ever. 
 
Taller plants healthier, larger harvest, and no sun scald. I had to keep raising the shade cloth cuz the plants just kept growing. We have lots of marine layer this year, so I havent put it out yet. But I am ready if there is a prediction for sun and heat. 
 
ThePickler said:
I would agree with you John.  Alot of them had tons of new growth come out of their stems.  That stuff looks great, the canopy's look rough but are coming around.  The gardener who moved his plants into the greenhouse two weeks before I did has had no issues with his plants.  This was probably the case. 
 
Any thoughts on this:  plants take more time to harden off the longer they've been under grow lights? 
 
Some experienced folks are probably smacking their foreheads saying: "NO $HIT SHERLOCK!" because they already know the answer.
 
Thanks
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I think zeroing in on one element is a difficult way to go. "The longer they've been under grow lights" is a LOT of things. Your BEST bet probably is to experiment. Take a few and do this. Take a few and do that. Bring them out in stages. I myself like to put them outdoor under 4 mil plastic for a week. This gives a partial block to the UV. On the topic of grow lights, some of the LEDs now do emit some UV, and it would stand to reason that would only assist in the UV hardening process. I grow in Maine, on my 8th year, and I am STILL seriously struggling with the transition from indoor to outdoor. I think I am allowing their roots to get too cold. They shut down (leaf yellowing) and produce useless tiny pods (like within a couple weeks). Different subject. But it illustrates how easy it is to miss something, if you're not looking for it, or better said, if you are looking for something in particular, you will not hear with the plant is telling you.
 
JohnT said:
I grow in Maine, on my 8th year, and I am STILL seriously struggling with the transition from indoor to outdoor. I think I am allowing their roots to get too cold. They shut down (leaf yellowing) and produce useless tiny pods (like within a couple weeks). Different subject. 
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You're right, it's a different topic.  But I will chime in and say that you are exactly correct in your diagnosis.  You really don't want to put plants in small biomass containers out when the temp gets much lower than 55 degrees.  Yellowing is a very determinant sign of nutrient uptake hindered by temp.  This is when the xylem in the plant begins to become more viscous, and the signs of Potassium deficiency are mirrored by this uptake disruption.  It is one of the first signs of cooler temps in the fall.  Even here in Florida, I have a small window of time where plant growth shuts down completely for a few weeks, and that's exactly what my plants do.
 
I use a 30% shade cloth down here but our climate is very different.  Soil in containers tend to get a lot hotter than soil in the ground, something else to consider.  How hot is the soil in your plants root zone?  If it's under 90 during peak heat, I wouldn't worry about it.
 
I plant in soil in the garden. Clearly this is my issue solid7 and I need to wait till July to place them out. Very hard to do because I am already on a restricted time window. But it's clear to me now.  Thank for the insights. Every year, is the same theme. This years variation was I planted on the 15th and 17th, and on the evenings of both the 24th and 25th, the outside low air temperature was recorded at 46. Something like that always happens.
 
JohnT said:
I plant in soil in the garden. Clearly this is my issue solid7 and I need to wait till July to place them out. Very hard to do because I am already on a restricted time window. But it's clear to me now.  Thank for the insights. Every year, is the same theme. This years variation was I planted on the 15th and 17th, and on the evenings of both the 24th and 25th, the outside low air temperature was recorded at 46. Something like that always happens.
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Still, same story.  Ground temps.  Check the temp 6" below the soil line, and see what it comes out.  If it's not fast approaching 60 degrees, it could be problematic.  You may want to invest in some nursery cloth, and use it as a solar panel.  The added bonus is that it keeps weeds down.
 
solid7 said:
 
Still, same story.  Ground temps.  Check the temp 6" below the soil line, and see what it comes out.  If it's not fast approaching 60 degrees, it could be problematic.  You may want to invest in some nursery cloth, and use it as a solar panel.  The added bonus is that it keeps weeds down.
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I am in agreement. My initial post may have been misleading.

I have (for better or worse) decided to grow without cloth / plastic / what have you. My health is not that great and the energy is not there, nor the money really, for the hobby. I also see it as a challenge, soil growing. I have use the fabric in the past. It is a good thing.

I just need to use self control and bring my starter/seedling tray indoor (at night) till July 1, and then plant.
 
Thank you again for the information.

 
 
Sorry to hear that, friend.  If I were any closer, I'd offer to help you out, with only the humble request that you give me 2 square feet of soil to plant an extra of my own. (that's my standard fee for locals)  I hope you find a workable solution.
 
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