Lighting for Phals, Catts. and Dens.--natural vs. artificial

[SShide77]

Hi,

I am fairly new to orchid growing, but have also just moved into an apartment that has fewer lighting conditions than my last home. I have one large southeast facing window that gets pretty bright light in the morning and is fairly bright the rest ofthe day, but not hit directly by the sun. I have my phals on a counter between my living room and kitchen that is facing that window but is about 8 feet back. I have installed a fluorescent fixture above the counter my phals are on so they get a little more light.

I have my catt. hybrid and dendrobium on my south east windowsill.

My question is, since the catts and dendrobiums require more light, would it be beter to put them under the fluorescent fuxture and move a fewf my phals to the windowsill? Or, when possible is it better to give them (catts and dens) natural light rather than artificial?

Thanks,
Sarah

[mehitabel]

Hi, Sarah. In my opinion, fluorescent tubes are not usually enough light for blooming catts or dends. However, it would depend on the *height* of the plants.

The reason is this: light falls off by half for every foot away from the source. So, especially if tall, the catt and dend have to more than a foot away from the bulbs. And light that was 1000FC directly at the bulb becomes 500 FC when the tube is raised one foot. That's why phals do better under tubes than catts do-- even large phals tend to be short. And why HID or other more intense lights are recommended for catts-- the more intense light "reaches" further.

If the orchids were mine, I would keep the catt and dend in the window, and move the phals, with the fluorescent fixture much nearer the window than 8 feet.

Think about it-- if the sun is hitting the window at 10,000 FC (outdoors at high noon on the longest day)... Then, at 8 feet away, the light from the window has fallen off to less than 100FC. It would be at around 1000 FC three feet or less from the window. And the light on the window has to be less than 10,000 FC since it is not overhead outdoor sun.

Phals can't handle hot direct midday sun, but they can handle a lot more light than most people think, and will grow and bloom much better in more light.

You'll surely get other answers, and maybe some that disagree. But I hope you will consider the light fall-off curve in placing and lighting your plants.

[Tobi]

Hi Sarah,
From what you are telling us with your southeast window, it would probably do well with
your Catt and Den. I would go with the natural sunlight and later light rather than
additional artifical light. If the leaves remain a medium green color and you are getting
new growth, then you have a pretty good chance of getting them to bloom.

[11Orchid126]

If it's at all possible, near the end of May you can put the catt and the den outdoors and give them as much sunlight as they will take without burning. If they stay out until just before the first frost, this may be enough to help them bloom and hold them over through the dull winter days.

[kmarch]

If I understood your descriptions correctly, I think your setup as it is, phals under lights, dens and catts in the south-east window, is perfectly fine. The window will be brighter than under the lights and catts and dens need more light than phals so I think you're good as is.

[SShide77]

Thanks for all your help! One other thing, i just found a slug crawling up my den. this evening (eew!) These plants are inside and have never been outside since ive owned them, is it possible that i have slugs in the pot?

[Tobi]

It's possible. I know snails will inhabit some medias. Pull the plant out of the medium and
check around. They should be easy to spot.

[Brooke]

If you have a slug, you could have slug eggs. They are small round, rather opaque things.

How far from the light fixture is your phal? More than a few inches the light is almost useless. Can you put the phal in back of the others to get some natural light but let the others shade it?

Brooke

[Fishmom]

Here is another aspect to the lighting questions. I have two south-facing windows, one with more overhang than the other, and consequently less light. The less sheltered window starts getting bright light about 2 p.m. and gets some direct light. Due to double pane windows, it doesn't get hot enough to burn leaves. The other window gets bright light a little later and gets little direct light, only late in the day. When you are measuring foot-candles, how long a time does a cattleya need high light? Are light totals cumulative? It obviously changes during the day. I have a catt which has not bloomed, but it has not been the bright room very long as we recently moved. I'm hoping it will like it's new situation and reward me with a bloom this year.