What does (blank) foot candles, mean?? Please Help!

[Hedge]

Originally Posted by RosieC

Well I learn something every day.

Yeah, only in my case it is often the same thing I learnt yesterday!!!

[RosieC]

Originally Posted by Hedge

Yeah, only in my case it is often the same thing I learnt yesterday!!!

Yeap, I know that feeling too

[susiep]

Jerry, thanks for the info. I am trying to establish better lighting situations for my orchids so I recently purchased a light meter. It measures in footcandles. Were the numbers you mentioned earlier in lumens or footcandles? I know what you mean about the heat vs light. Very difficult thing to balance. It seems that sometimes you need sunburned leaves to get flowers. Especially in south Florida and with sun loving plants! I may need to rescreen my shadehouse. (not looking forward to that) I bought the meter to check that out before I started ripping things apart.

[Ross]

Unfortunetly I often see such responses as above stating noon sun = something and "heavy shade" = something else. While noon sun in Ft Myers on a blue sky day may be 10,000-11,000 foot-candles, I assure you that at 45 degrees latitude it is way less than that. I measure approx 4,000-5,000 foot-candles in full sun in June in northern Michigan. I grow most of my orchids at 2500-3000 foot-candles. Heavy shade here in Michigan measures closer to 700-800 foot-candles. I still say the only definitive way to know for sure the strength of your local light (sun or shade) is with a good light meter. Not the cheapy mass-produced ones, but a calibratible one meant to measure within a couple lux/lumens.

[susiep]

I know what you mean Ross. The meter is not the "end all" when it comes to figuring out your lighting situations (or problems). But it has been helpful. The first one I got was only $8 at Home Depot. Not useful at all. The sensor was on the same side of the device as the gauge. Made it almost impossible to read in tight spaces (like near the roof screen of my shade house). The second meter I bought was better. About $30 from Broward Orchid Supply. Measures in foot candles. Has a wand that allows you to measure the light directly on the leaf from more than a foot away. Most importantly it confirmed my concern about my shade house being too dark. Not only that but the distance from the screen, glass or other barrier is more important that I realized. Unlike outside where the light (even filtered) is no different at ground level or 10 feet. The number of inches from the screen really makes a difference.