What % Shade Cloth To Use
 

I am in the process of building a pergola and I'm planning on hanging my orchids under it during the summer months. The pergola is in full sun from about 11am to 6pm, so during the hottest part of the day. Also, I'm in zone 7b, have hot humid summers, and can keep my orchids outside from May to Sept. I grow a mixture of vandas, cattleyas, and encyclias. I'm going to buy shade cloth to cover the pergola with but I'm not sure which percentage to get. Is 30% enough? I want the vandas to have plenty of light but would also like to be able to move some of my cattleyas and encyclias out of my greenhouse.

Can't answer yet. It depends on where you live:
- How far north do you live? (a surrogate for how intense the light is.)
- What your summertime temperature range? Hot to you might be barely warm to me.
- What is your summertime humidity range?
- Is there much air movement day or night during the summer, or the air is normally still?
- How often is it cloudy?

- northern Alabama
- 90's during day, upper 60's ~ lower 70's at night, the heat index occasionally gets above 100, but the actual temp rarely does
- humidity averages about 70%
- there is almost always a breeze during the day
- sunny most of the time, maybe 1 to 2 cloudy days a week at most with afternoon thunderstorms

I seem to recall cambriawhat lives in northern Alabama. He puts plants outside for the summer. Look up his posts and see how he grows. He has some plants under shade cloth and some hanging under trees.

You may have to take deer precautions.

Ok. I'll look them up. Thanks.

Cambria lives in KY.

Where are you getting the shade cloth? If from a g/h supply company they will be able to recommend the level best suited for your area of the country.

Because the vandas need a lot of light...you might want to consider two shade zones...1 for the catts and another for the vandas. I have 3 zones med light plants, high light, and super high light.

I like your idea about setting up different regions, especially since I have both semi-terete and terete-leafed vandas. I am ordering from a g/h supply company so I'll call and ask what they recommend.

I live in your zone. I grow catts, oncidiums, phals, paphs. My outdoor setup is an enclosed patio, 8 x 16 that I drape a 65% shadecloth over. I have a two plastic shelving units. The catts and onc. go on the top shelf. The phals and paphs and others go on the lower one. I have been very successful with that setup. I think the 30% will be too little. If you are getting sun the entire time I suggest two options: 1) 70-80% shadecloth; 2) consider a misting system, especially if you have vandas.

My 2 cents.

I wanted to add a follow up in case anyone else is looking for this info.

I ended up going with 40% and 60% shade cloth. I put my strap leaf Vandas and some of my more light tolerate Cattleyas under to the 40% and the rest of the Catts and the few oncidiums and dendrobiums I have under the 60%. My semi-terete and terete leaf vandas are growing without any shade after 11:00 AM. Everything seems to be getting about the right amount of light and I have had plenty of blooms this year. No sunburn, though most of the Catts under the 40% have a purple tinge to their leaves. I will caveat that it has been an unusually rainy summer so far, so more cloudy than usual for this time of year. I may end up needing to move a some of my semi-terete leaf vandas under the 40% and some of my catts from the 40% to the 60% as it gets hotter and dryer through August.