Need help with changing light on chids.

[justjill3]

I am upgrading my lighting on my plant stand. I am currently "growing" my chids under 5 year-old T12 flourescents. My handy-dandy, shiney and new light meter tells me what I'm sure you'd tell me. THERE'S NO DARNED LIGHT! I am switching to brand new T5 HOs (4 bulbs on each shelf). and have read that orchids should be exposed to higher light gradually. Well, I am not sure how to do GRADUALLY with a light stand. How much does this matter? If it really matters, do you have any suggestions?

[Ross]

T5's put out a lot of light, that's for sure. And you can't run a 4-bulb fixture with only 2 bulbs - it will damage the fixture and perhaps the bulbs. You also can't use a dimmer unless the packaging says specifically you can. Can you hang layers of some shading material between lights and plants? How far below the new lights will your plants sit?

[FinnBar]

that's a lot of light.. especially after the (light?) levels they're used to

one alternative i can think of is to cut tin foil into strips and roll them around the tube. then start removing them/exposing tubes gradually. be patient...

[justjill3]

Quote: Can you hang layers of some shading material between lights and plants? How far below the new lights will your plants sit? (Ross)

I haven't decided how far below they will sit. I'll stack something under them to account for changes in distance. The max. is about 2 feet on top shelf and 3 feet on the bottom shelf. I like your idea, although I will have to think about the material.


Quote: ...cut tin foil into strips and roll them around the tube. then start removing them/exposing tubes gradually. be patient...

I DO have tin foil.

[justjill3]

Quote: Can you hang layers of some shading material between lights and plants? How far below the new lights will your plants sit? (Ross)

I haven't decided how far below they will sit. I'll stack something under them to account for changes in distance. The max. is about 2 feet on top shelf and 3 feet on the bottom shelf. I like your idea, although I will have to think about the material.


Quote: ...cut tin foil into strips and roll them around the tube. then start removing them/exposing tubes gradually. be patient... (FinnBar)

I DO have tin foil.

[Ross]

You can use gauze curtain material or window screen. Double or triple layers to add shade.

[justjill3]

I think I have a defunct gauze curtain. I'd have to buy window screen. I'll have to play around with this.

[calvin_orchidL]

Hi Jill! I was/am in a similar situation - I had a really old T12 2 bulb fixture. But I find that it works really well with 2 40W bulbs for phals and other low light growers, if mounted around 4 inches above the plants. Obviously things become problematic when they start spiking, but for growth, it's great, especially if you have a long growing area like a shelf or something.

T5s put out about 4-5000 lumens of light each bulb so you're looking at a whopping 20,000 lumens! But remember that light decreases by an inverse square as you move away from them, so you can simulate much lower light levels by just moving your lights away half a foot. I'm assuming you're going to hang these anyway, so the best control you could hope to get would be to adjust the height gradually and check the light levels falling on your leaves with your light meter. That way, you can make a completely smooth transition to the higher light conditions by decreasing the distance by an inch or so each week.

Where are you getting your T5s from? I use compact fluorescents and I find them cheaper and versatile, but I am definitely attracted to the high light output of those T5s!

[Ray]

Calvin is right - distance is the key.

The reason one moves plants gradually into higher light levels is to prevent burning, but that's usually in reference to the sun. I could be wrong about this, but it seems to me that at 2-3 feet, even those HO T5's won't be bright enough to burn the plants.

I would also recommend replacing the bulbs annually. Five-year-old fluorescents at three feet distance are, as you noted, worthless.

[AHAB]

I have a bunch of Icecap vho ballasts (prior use was for reef tanks) I would like to use them for my orchids but I am not sure on the brand or spectrum of bulbs to buy any suggetions?
Thanks,
AHAB