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shade cloth vs. tarp

  • Thread starter mass
  • Start date
Need to start thinking ahead about the upcoming summer heat.
I have a brand new tarp here I can throw over the GH for a little extra shade. But a friend pointed out that that may actually cause the GH to heat up even more.

The questions:

Has anyone ever used a blue tarp as a shade provider, and did it work?
How much does a 50% shade cloth actually help to cool a GH?
If temps are 90*F-100*F outdoors, what's the best (non-electrical) way to keep a GH in the upper 70*s-mid 80*F's?
 
Having slept under many a tarp in the wilderness/music festivals, I think I can safely say that that would provide the opposite effect of what your trying to do mang. Any color like that thats darker in value will collect heat. I'm no expert on this subject but I believe that a shade cloth is your best bet for sure!
 
makes sense..
Guess it's time to go shopping! Thanks brotha..
 
If temps are 90*F-100*F outdoors, what's the best (non-electrical) way to keep a GH in the upper 70*s-mid 80*F's?

Maybe im wrong (I have never owned a greenhouse)
but logic seems to dictate (to me) that it will *always* be warmer in a greenhouse, than outside.
It seems like it would be impossible to make it cooler than outdoors, non-electrically..

the best you can do is try to diminish the heat (with shade cloth)
but I dont see how you can make it *cooler* than outdoors..

a greenhouse, by its nature, will always trap heat.
If its 20 degrees outside, it will be warmer in the greenhouse.
if its 50 degrees outside, it will be warmer in the greenhouse.
if its 100 degrees outside, it will be a LOT warmer in the greenhouse! ;)

you get the idea..
shade cloth will make it "less warm"..but not cooler than outside..

Scot
 
good point..
please excuse me, my stupid is showing.
 
when I worked in nurseries in Texas, we used 70% shade cloths over the outdoor plants. They certainly kept the ground under them much cooler in the summer heat.
The large greenhouses were using swamp coolers the size of a small school bus!
 
Shade cloths are surprisingly affordable on ebay. I figure a good shade cloth + multiple daily mistings with the cold hose water inside the GH should do the trick.

LARRY!! I missed ya buddy.. I've got so much to tell you. I'll email ya!
 
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Suspend the shade cloth over the GH will help aid in cooling too.
 
It's more of a hoop house than a greenhouse really. Will definitely keep it completely opened on those hot days..
Thanks for the tip JB.
 
  • #10
All of my plants are grown outside here in So Cal. While everyone here is correct that neither tarp nor shade cloth will "cool" the green house, I feel one would help you keep the temps down more so and serve a better purpose. A tarp will shade the greenhouse but trap moisture and heat and not allow light in. Shade cloths come in just about every % rating that you can think of and do not trap much moisture or heat but let enough light through to make sure your plants get as much natural light as possible. I use both 55% and 75%. Between the two I have been able to control my temps quite well.

Neither will drop your temps below ambient temps, but in my experience shade cloth helps considerably in stopping sunburn and overheating. I find it the most useful in stopping the water in my trays from being heated by the sun. The water stays MUCH cooler using shade cloth.

That's just my two cents, and you still can't buy bubble gum with it.
 
  • #11
That's just my two cents, and you still can't buy bubble gum with it.

That made me laugh out loud. Which is saying a lot for 9am..

Thank you for the input, very informative.
I have little experience with outdoor growing, and zero experience with shade cloths.
Question: using 55% and 75% = 105% UV blocked, wouldn't that be like growing plants in the dark?
 
  • #12
That made me laugh out loud. Which is saying a lot for 9am..

Thank you for the input, very informative.
I have little experience with outdoor growing, and zero experience with shade cloths.
Question: using 55% and 75% = 105% UV blocked, wouldn't that be like growing plants in the dark?
Nope, because the first piece blocks 55% of the available light, leaving 45% of what you started with. The second piece blocks 75% of that remaining light leaving an amount of light you can calculate yourself because I'm still working on my daily caffeine requirement!
 
  • #14
That made me laugh out loud. Which is saying a lot for 9am..

Thank you for the input, very informative.
I have little experience with outdoor growing, and zero experience with shade cloths.
Question: using 55% and 75% = 105% UV blocked, wouldn't that be like growing plants in the dark?


Not together. Some places I use 55% and other places 75%.
 
  • #15
50% should be really all you need for nepenthes and things. Remember these are high blight plants. You trade off less light for cooler temps.

But with that said...remember I have fans and other forms of cooling going too. My point is you are going to need air movement even in a GH of hoop house situation. Is your hoop house enclosed on the ends? Either way air movement is key. A hoop house is just a type of GH. Neps as I said like high light for the most part and don't like the shade. But its a trade off growing in a little less light for cooler temps. Your going to have to play with it and tweek it to your area. My GH is shaded a little by a tree except during parts of the day. 59% shade is a big deal and some plants had to move to the front of GH where more light gets in. My helis are a prime example. But if I font have the shade cloth then the temps get too hot even with my AC going.
 
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