Quote Originally Posted by Terryros View Post
Photosynthetically active radiation (PAR) quantifies photons in the wave length range that supplies photosynthesis. You need a PAR meter to measure this way. A standard foot candle meter usually measures additional wavelengths, so the reading isn’t as precise for what plants specifically need. However, the ratio of 5:1 foot candles to PAR peak photon density may be a rough approximation. If 300 peak photon density is the most that you should need for constant lighting over the course of a day, that would be roughly 1500 foot candles. I think it is important to remember that many orchids are sensitive to day length and giving them more or less day length than they are genetically programmed to want may inhibit best growth or blooming. The range from 11.0 - 13.0 day length will satisfy any Cattleya. An indoor light grower can give this exactly. A green house grower in northern latitudes is mostly stuck with long day length in the summer. In the winter, they can give supplemental light to keep to a minimum of 11.0 hours.

The daily light integral for my Cattleyas varies from about 10 to 12 moles/m2 over the course of the year. This is consistent with a few other reports of PAR light exposure for higher light orchids in green house conditions. Ray’s calculations work in an indoor plant room with LED lights.
Please for a little more help. I am understanding the light levels plants need averaged out thru the day, and par light is different on light meters, that a decent par meter will cost about 150.00...but the choices on led models is confusing. I am going to have a 3' x 12' grow area full of bs catts, and i figure i should get 4 lights, one to cover every 3' x 3' area..possibly 500w-1000w each???? The prices vary, from many that are $75 to $150, and some that sell for $700 each unit?????....times 4 that's expensive..And some are boxes or panels full of small blue and red lights only, some have small blue, red and white lights stating full spectrum. and there are large white led spot light looking lights with cree bulbs, advertised as grow lights...(I think i want whitish looking light for aesthetics, as its in my living room).. knowing there are a lot of cheap crappy ones out there that don't work, its hard to try to find a good price on something that actually works,,,can someone please name a few reputable brands or models that might suffice for growing catts in a 3' x 12' area...