When to Measure Light

[dianecty]

Hi guys!!! I am buying a light meter to help my orchids. My question is what time of day to measure the light.

I keep my orchids outside and of course, the amount of light changes throughout the day.

When should I measure the amount of light they get so that they don't get underlit or overlit?

Also, the highest capacity of the hydrofarm light meter I am thinking of buying is 5,000 footcandles. Is this high enough for outdoor daylight?

Thanks everyone!!!

[isurus79]

While Ive never used a light meter, I would measure whenever you feel it is the brightest time of the day. If you dont know when that is, measure at the top of every hour or every half hour on a sunny day from early morning until late afternoon so you can get a range of light levels.

[Ross]

My question would be: what use would be this measurement? If a certain orchid is advertized as wanting high light (2000+ foot candles) is that over the length of the "day" or the peak of the day. There's a big difference. Many people have learned from experience that when they grow outdoors, they can't expose certain orchids to full sun in Hawaii or Florida, yet others love it. But full sun is constant over the day length, thus the question being asked. I suggest measuring light (as you suggest also) on a fixed interval, on a sunny day (clear skies) once per hour over the full day from dawn till dusk. Then average the readings to see how much light was produced. Most growers don't mess with this (as I think in your case) but growers under lights do. Or moving from greenhouse/outdoors to under lights or visa-versa. Just my 2 cents. To sum this up, for me, I have found approx 1800 foot candles (dismal outdoors) to be optimum under constant t5 lighting. I'd love to hear what the average is over dawn-dusk in a southern latitude.