Shade Cloth percnetages defined and questions

[Uechi]

I live in Clearwater, Florida and we have plenty of light too much in fact. I have my orchids placed in several areas in my screened porch, but it is still way too bright from 11:00 am till 3:00 pm. I have decided that shade cloth will do the trick. The problem is the more I read about it on the Internet,the more confused I get. One source says 70% shade cloth, for example allows in 70% of the light and blocks 30%. I read another source and they say 70% shade cloth blocks 70% and only allows 30%. Which is it? I was planning on buying cloth that blocks about 40% of the light. Is this to much or too little? Several growers use 50, 60 and 70%. I understand that various species require different levels of light ,but I would think there is a compromise percentage. I also would like a recommended source/s. Home Depot and Lowes, at least around here, sell the same brand and it doesn't really tell how much light it blocks or lets in. Thanks for the help.

[Jerry Delaney]

Uechi,
I think that one thing that makes this so confusing is that when one talks about light transmission through a greenhouse covering such as glass, polycarbonate, fiberglass etc. the percentage expressed is the percent of light the covering lets through. When considering shade cloth, the percentage expressed is the percent of light that is BLOCKED. Thus, 70% shade cloth will allow 30% of the light available to pass through. In most parts of the country, a lot of people will opt for a 60% - 63%. I have always felt that the proper way to decide was to take a good light meter and measure the light intensity at plant level at ~12 noon and use that reading to determine the proper percentage of shade cloth you would need to give you the light intensity you desire. I'm sure that everyone has their own preferred way to determine the % desired and if it works for them, that is hard to argue with!

[Uechi]

Thanks for your inputs Jerry. Regards

[Don Perusse]

I live in S. Ga. and had the same question but never asked. Thanks guys for your input and answer.