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Regarding sunlight

This is a discussion on Regarding sunlight within the General Orchid Culture forums, part of the Orchid Culture category; Hi, I live in an appartment in Copenhagen, Denmark where the only reasonable place to ...

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  1. #1
    Korxi is offline Orchidiot
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    Default Regarding sunlight

    Hi,

    I live in an appartment in Copenhagen, Denmark where the only reasonable place to put my orchids is in the windowsil. This ofcourse makes them exposed to sunlight some hours a day. But we just had new energy saving windows installed, and they block out some light and energy (it's visible when I open a window the light coming in there is much brighter then through the glass). Furthermore the climate in Denmark is more or less the same as in the lower part of Canada - only at sea level.

    So I'm thinking: Does the sun harm my orchids when it's through those windows?

    In the entire 2 months I've been growing orchids (Very new, but very enthusiastic grower) they have been in that window, and no black spots, yellow leaves etc. has formed..

    Christian

  2. #2
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    Those new windows really cut back a lot of light, and they especially reduce some of the UV rays. I grow my paphs in a garden window in southern california and they do fine.

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    You're far enough north, Christain, that the strength of the sunlight is much weaker. How much light your plants should get depends on what genera you have. Dends and Catts will want all the light you can give them. Oncs, Phals will probably not mind full light. Paphs are good with partial direct light, or bright indirect light.

    Watch the leaves for sunburn - that's how you'll know it's too much. When in doubt, I up the light level.

    Julie

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    ATester is offline Minster of Silly Flasking
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    Default Light

    I second Julie here, the first indicator of too much or not enough light is a change in the leaf colour, also watch out for change in leaf turgor (whether or not they become limp) with change in the light and temperature. I have very specific spots in my apartment (a little further south than you) for specific plants. If you are concerned with the amout of light there are a couple things you can do to check and see if they are getting enough light. One way is you could buy one of those foot-candle meters, or if you have one already it wouldn't be necesary to spend the money, use a camera and use the light meter built in. I can find the equation that will give you the approximation: 10 x f˛ /t x ASA (kind confusing, let me explain. f is the f-stop or apeture of the camera lense setting, t is the shutter speed in seconds and ASA is the ISO speed of the film...so: say you are set at ASA 25 and your shutter speed is 1/60 of a second, a lense opening of f2 should work out to be 100 fc's and f11 would be about 2800 fcs). But, math usually stresses me out, so I just stick to the first indicator that anything is a'miss...watch what the plants tell you

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    Oh Aaron, you're trying to be the mad scientist again!

    Christian, what Aaron is saying is absolutely true about light levels, but your plant has a different agenda.

    When we measure light levels, we only capture that day's weather (cloudy, sunny, etc) at that moment in time. Those readings will vary from morning, noon, and evening, from day to day.

    Your plant cares about it's average light level across all the hours and all the days. So unless you measure light at different times of the day and repeat it on many different days, and then average it out, the light reading doesn't tell you much. You can compare areas at a given time for more or less light, but I think it's pretty meaningless.

    I'd keep it simple and give a Dend, Catt, and for you even a Onc and Phal, full light. I'd give a Paph a bit less, but not by much.

    Julie

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    Korxi is offline Orchidiot
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    Quote Originally Posted by Piper View Post
    Your plant cares about it's average light level across all the hours and all the days.
    Oh, I would have thought that there was a maximum amout of light/heat/UV (which is it??) that a given orchid could handle, and if this (or these) amount(s) were exceeded, the plant would suffer from sunburn.. ??


    I might just try out that equation on my camera, Aaron! Just to be clear (and practical) what you do is:

    1. Set an ISO/ASA value e.g. 200 (and set light metering to matrix?)

    2. Point your camera at sky from orchid perspective

    3. Adjust aperture and shutter speed until the "light-meter-scale-thing" is at value "0"

    4. Note those aperture and shutter values and put in the equation
    ??

    Christian

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    Actually you want to measure the amout of light falling on the leaves, so you would meter off of the plant. Also, here's another thing to keep in mind...you want to make sure the leaves are absolutely clean and free of dust, dust robs light like you wouldn't believe...but no one likes to have dusty leaves on their plants, so it shouldn't be an issue. I go around and wipe off the leaves of my guys in the windows once every three days or so.

    Yeah...mad scientist...hee hee hee....I haven't tried light metering off of my plants (unless to take the rare photo) to measure foot candles in forever...I prefer to keep my mad science tendencies for the flasking

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    Christian, if you want to measure the light, then do so at different times during the day, and record what you get. Maybe 9am, 12 noon, 3pm, 6pm. Record them, and then come up with an average daily exposure for each location.

    It's not just intensity, it's also duration. Max intensity will cause sunburn, but the duration together with the intensity will determine how happy your plants are and whether they'll bloom.

    McJulie

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    Thank you for the freat advice! Today it's really cloudy - but next time the sun comes out I'll just do a reading to see if it's totally off. Otherwise I also like to just "listen" to the plants..

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    Unhappy Help me!

    Quote Originally Posted by ATester View Post
    I can find the equation that will give you the approximation: 10 x f˛ /t x ASA (kind confusing, let me explain. f is the f-stop or apeture of the camera lense setting, t is the shutter speed in seconds and ASA is the ISO speed of the film...so: say you are set at ASA 25 and your shutter speed is 1/60 of a second, a lense opening of f2 should work out to be 100 fc's and f11 would be about 2800 fcs). But, math usually stresses me out, so I just stick to the first indicator that anything is a'miss...watch what the plants tell you
    Hi

    I found this post when I was looking for information on light levels, so I thought I would give the equation a go. Bear in mind, I point and shoot - I don't actually manually doing anything, but my camera gives me F-stop, speed and ISO ratings for each picture taken.

    Using the equation I have quoted, I get results like 209 fc's. This was with the figures F2.8, shutter speed 60 and ISO 160. Isn't this a bit low for indoors? So I went outdoords: I took a photo of a paving slab in the sun and got F8, speed 400, ISO 160. Using the equation 10 x f˛ /t x ASA I get 10 x 8 squared / 400 x 160 = 256. How can there be only 256 Fcs outside???? Even using Aaron's example values of F2, speed 1/60 and ISO 25, I don't get 100.

    Having tried loads of photos and loads of readings, I wondered if I am doing the equation wrong. So can someone please tell me what I am doing wrong, or is the equation written down wrong?

    Help me please, I am tearing my hair out here!

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