I got a light meter, and am surprised at the readings
I bought an inexpensive lux meter the other day to finally have a clearer grasp of how much light my orchids were getting.
Before I bought the thing, I had guessed that my plants were receiving an amount of light on the low end of their requirements, but still within an acceptable range. Boy was I wrong!
It turns out they are receiving more like one tenth of their requirements. This is blowing my mind a bit...shouldn't they be dead at this point?
The paph/phals are receiving around 1169 lux, as shown here...much less than their minimum light requirements of 10,000-15,000 lux.
Not much better for this oncidium, which is receiving 2,290 lux (the meter is in x10 mode here) instead of the recommended 20,000.
I must be missing something because this just doesn't seem right.
My sources for light requirements are the AOS culture sheets. Lux are roughly converted into footcandles by dividing by ten.
I remember when I first got my light meter (several years ago)...I was shocked at how little light the plants were getting. What seems so bright to our eyes...well...our eyes are virtually worthless gauges of light requirements for plants. My set up today...w/all the lights...glows like some kind of spaceship when people look at my house after dark. For those who first walk into the space...they feel like they need sunglasses. Bright would be an understatement.
As for how your plants are still alive...many plants can survive for years under less than ideal light but you won't get them to bloom.
A light meter is an invaluable tool in any orchid grower's arsenal. You won't regret that purchase! Getting the lighting right...I foresee LOTS of blooms in your future.
Just wait until you start testing for TDS and PH. You'll be like a mad scientist.
If you plan on giving the plants more light, do it gradually or you will wind up like I did with a bunch of burned leaves. Not a pretty sight!
Lol. I am going to take a chill pill and let mother nature do her thang. Right now they're dealing with an 8-hour photoperiod and the sun at a very low angle. In six months, the days will be 16 hours long and sunlight will be pouring in those windows. Can't wait to take some light meter readings then!
"If you plan on giving the plants more light, do it gradually or you will wind up like I did with a bunch of burned leaves. Not a pretty sight!"
So this is why i manage to scorch them in the summer. I guess when you add up all the window obstructions and overcast days they are getting much less light than we think.
But then some plants can be surprising. I gave a coworkers a little Oncidium (One of the Twinkle parents) a few years ago. It manages to bloom with office lighting and a northern window exposure.
I also have a very basic (inexpensive) light meter and like you, when I bought it, my readings showed up very low. Granted, I was testing the light levels underneath fluorescent lights, which those meters are apparently not that great at measuring. Either way, the readings were showing light output was about 1/4 - 1/2 of recommended minimums for my plants, but I knew that was wrong.
Sometimes just looking at your plants will give you a better idea of whether they're in proper lighting conditions, though the effects might take longer to show up. For instance, despite the low light readings, I could tell that some of my plants were in the high level of their light requirements because they'd develop red pigments/coloration in the leaves, or they were producing light green leaves (yellow/lime colored). Plants that aren't getting enough light may stop growing new leaves or slow way down, and the foliage will become dark green.
I think as others have pointed out, it's fall/winter in the northern hemisphere, you're not only getting a reduced number of hours of natural light, you're also getting reduced strength (generally). But also, the amount of light is going to vary day to day depending on cloud cover and other factors and it's going to vary hour by hour.
I tend by nature to be technically oriented so I have several light meters of various kinds and I use them a lot, but I think there is still a lot of art as well as science to measuring light in a growing area. There is duration as well as intensity, you've probably noticed that your readings vary wildly depending on how you orient the sensor to the window, and as others have pointed out intensity will vary a lot with the time of year, time of day, weather, etc.
If your plants are growing and blooming well then I wouldn't rush to change anything no matter what the meter says. If they could be blooming better then I'd increase the light somewhat, not all at once but gradually as other posters have said, watching carefully for any sign that the plant isn't happy.
We try to take lots of readings with our meters, to get an idea how the intensity in different spots varies during the day, and over time and seasons. We got some unexpected results, and we're still learning.
That is crazy!!! Are you sure the digits are correct? lol
but seriously, your plants look all perfectly fine to me.
How long have you have that paph and phal in that location??
I doubt those plants will look that healthy and flower normally if the light they are getting is indeed one tenth of what they need.
---------- Post added at 05:06 PM ---------- Previous post was at 05:02 PM ----------
Ok, I just watched your video.
I don't use light meter as my plants all grow fine.
Judging by the brightness of your growing area by the window, whatever the machine says, it looks bright enough for them to me.
Maybe you measured it on a very cloudy day? It looks rather dark, but then I see some other scenes where the window sill appears much brighter and then I also see a scene with sun light shines in through the window.
Hey NYOM, you're right, I did measure on a cloudy day. Today was sunny and the reading got up to 3000 for the phal/paph and up to 3800 for the oncidium. Still below their minimums, though!
The pic with the sunlight shining in was taken in July. I included it to illustrate the range of lighting conditions that exist over the course of a year. I'll be sure to post those light readings when the seasons change!
I got a light meter, and am surprised at the readings
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