Grow Light Question!

[TirSigel]

I was wondering if anyone has any experience with grow lights that they would like to share with me. I'm beginning construction of my over-wintering structure in the basement for my orchids. I have approximately 70 plants now so it will be 3' x 6' x 8' (tall). I've read all of the specs and it looks like for my needs I should get a 400 watt MH HID system. So far, so good, but now I see there's temp ranges, color ranges and all sorts of other things that I know nothing about. Does anyone have any advice on what would be a good baseline system for a mixed batch of plants. I'm assuming that I wouldn't want to stress them anymore over the winter which is why I'm leaning toward the MH for growth instead of the HPS for flowering...Thanks in advance,
Kevin

[Dazed]

Have no use for lights but hopefully this may get you some kind of response from those who do know.

[TirSigel]

Thank you for writing something!! :-) Doesn't appear to have worked. I'll keep trying.

[Magnus A]

Everything come down to your need.
What I can read out from your post you do not need a good display light but rather winter "storage" light.

In that case you should look for a high lumen output (how strong the light is) and that it put out a full spectrum light (all wave length in the visble range). The balance between different color is not crusial for winter light in my opinion.
You also need to think about temperature as a 400W MH give away quite an amount of heat, but this is seldom a problem in a basement (if it is not design as a pimary living space).

For display light there are same other needs. Then you need a good balance between wavelenght to display colors corect. Look for Ra values, close to 1 displays color more correct. Also color temperature can be used as a measure and I find color temperatures around 6000-6500 K to be good for visual displays.

I will not dig in to light spectra for growth or flowering as there is to little solid evidence for such statements. Others have to speculate on that.

[poetiscariot]

I grow under lights year-round, with a bunch of different genera. I have a really nice, very bright warm-spectrum Hydrofarm CFL fixture, one cooler-spectrum CFL spotlight, and two fluorescent fixtures that I use warm-spectrum bulbs in. I lean toward the warm spectrum bulbs because redder light is better for encouraging blooming. I didn't even look at HID lamps -- it seems like they were significantly more expensive than what I wanted to get into, and they get hot, which wasn't going to work for me.

Your lumens needs will vary with how far you put your fixtures from your plants. Essentially, if you want to buy fewer lights and light a bigger area with each one, you need high lumens. If your collection would work with plants right under the lights, lower-lumen bulbs should be fine.

If you stick to fluorescent and/or CFL bulbs, you can put them very close, because they don't get hot. One of my fluorescent fixtures is only about 8" from the tray where my plants sit -- it holds younger plants that want bright light and my bright-light miniatures. One is about 13" above the tray, and it gets my plants with higher moisture needs, with the ones that like more light in the center and the ones that like shade toward the sides. I put them all together so I can at least try to keep them evenly humidified as a group. The really bright CFL is hung in a window and has the "adult" sized Cattleyas and Dendrobiums, so they get that plus the window light. The spotlight is right next to it, in the window but behind a light curtain; it has kind of a motley collection under it, including my Zygo, my one big Phalaenopsis, some NBS Cattleyas, I forget what all. Basically, plants that maybe could be put in with my bright/high-humidity group, but are too big for that space.

If I had the money, I'd get three more big CFL fixtures and only use those. I've had my one for a couple years, and I've been really happy with how my plants seem to do underneath it -- but my favorite orchids are pretty much all high-light Cattleyas, so YMMV.

Dollar for dollar, the regular fluorescent fixtures were probably the best buy. I got a small cart with lights and trays built in to it for under $100 from an online retailer (on a pretty good sale). If you're just going to be using lights through the winter, that might be a good option for you, because although the lights are on the cooler side of the spectrum (even the "warm" ones aren't as warm/golden as my big CFL), you'd probably want to be encouraging vegetative growth more than flower production.

I also just noticed we're actually in the same place, so I'm growing with exactly the same light challenges you are (none in the winter). Hopefully this is useful for you to think about, even if I don't have experience with the exact kinds of lights you're considering right now.

[Magnus A]

I have one more thing you need to look out for. A good reflector as you do not want to light upp your walls and ceiling. In Europe, many lampholders are sold without reflextors...

[TirSigel]

Thank you for the responses. I think I'll go with the 400 Watt MH for the 3' x 5' room I'll be making. The walls will be painted a flat white for reflection. I'll post pics when it's done.