Indoor Lighting for Citrus (and others)

20 years ago

I have been searching around GW for info on indoor lighting setups and I think I've only succeded in getting myself more confused. Metal Halide vs Sodium bulbs vs. flourescents. Color temps for growth vs. flowering. Costs, energy usage, space, etc. I've also read the '10 Myths' post. My head is spinning...

Here's my situation: I have a south facing window that I planned to overwinter my citrus by. I realize given the grey skies of a NY winter that I should probably supplement them with lighting. I have a blood orange, red grapefruit,guava and lime tree ranging from 4.5' down to 10" high and plan to put them all together in front of the window to grab whatever light is available. I also have 3 smaller plants (tomatoe, pepper, maybe start a few seedlings in spring)that I just want to get through winter till I can put them in the garden.(the bedroom also has an east window for ambient light.) I plan to use mirrors or reflective surfaces to help but I would really like the citrus to grow a little (or a lot!)during winter if possible (a few flowers would be a HUGE bonus but I realize maybe unlikely). This setup would only be for winter as I would move the plants outside during summer.

I was gravitating towards Sodium or Metal Halide but I'm finding a lot of mixed reviews when they are put up against flourescent grow lights, etc. I know very little about indoor lighting and need advice from the experts.

What kind of lighting setup would you recommend for this situation?

Thanks,

Chops

P.S.- i have a very good light meter if that helps my setup.

Featured Answer

shrubs_n_bulbs

20 years ago

Do you know how much light you would like your plants to receive? And how much they are actually getting in that position? That would make it very easy to calculate the necessary extra lighting.

To put it in a nutshell, if you need more than about 30,000 lumens, get metal halide or HPS, probably HPS since you also have natural light. Less than about 15,000 lumens and you will be getting a couple of shoplights. In between, you can have many happy arguments :)

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Comments (7)

Joe
Original Author
20 years ago
Hmmm. I'm not sure how much light I want my plants to receive. Enough to grow, but I'm not sure how to calculate that into lumens. I know that citrus prefer at least 6 hours of direct sun.

As for how much they get NOW without a light setup, i guess i can use the light meter to calculate the lumens. But they probably only get 1 to 2 hours of DIRECT sunlight through the window as it is probably not big enough to cover all 4 trees.

Would I be able to plug a MH or HPS light into a standard 120V outlet or do I have to install special electrical work?
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nygardener
20 years ago
A 400-watt HPS light would probably work nicely. However, it will be tricky to place it so that the light doesn't shine out the window and disturb your neighbors, if you're a city dweller. HPS are more efficient and, as you say, you'll be getting plenty of natural blue light. However, MH is pretty close in efficiency and has a more natural, pleasant look; HPS are yellowish, like street lamps.

They run off ordinary wall current and must be hung from a hook screwed into a ceiling joist (similar to a wall stud). They're very easy to set up. You'll need a humidifier and a small fan nearby.

Even citrus trees need a period of winter rest, so reduce fertilizing now, fertilize very little or not at all during the winter, and don't encourage your plants to grow then. Ask on the Tropicals or Citrus forum about whether the light from a south-facing window, in a room kept fairly cool, is enough. If so, perhaps just try to keep your nighttime temps at about 60Â°, days around 65Â°, and make use of all that natural light. (This assumes that the sun isn't obstructed from shining in your window by nearby buildings.)

Either way, reflective surfaces are a good idea. White-painted walls are quite reflective. If it's a large room, consider having a room divider lined with reflective material (Foylon works well); that will shield the room from the light and redirect both natural and artificial light to your plants.

Here is a link that might be useful: Indoor Gardening Primer
jwmeyer
20 years ago
Ceramic metal halide. I still love it much more than either HPS or MH....
watergal
20 years ago
What is ceramic metal halide?
hairmetal4ever
20 years ago
I use 1000W for only 2 citrus and some smaller plants. They get about 3000 foot-candles at the top and 500-1000 in the lower inner leaves. However, they have NO natural light at all, so 400 might work if they also get some natural light.
shrubs_n_bulbs
20 years ago
Ceramic metal halide is a relatively new type of HID bulb which has a lower colour temperature (typically 3000K - 4100K) than traditional metal halide and a wider spectrum (CRI above 80, sometimes above 90) than traditional HPS bulbs. It is one of a number of HID lamp types that provide features intermediate between the narrow-spectrum orange HPS and the blue metal halide spectrum.