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Then There was Light

A basic primer on grow lights

Grow lights come in many spectrums, prices, and watts. Generally, there are four kinds: incandescent, fluorescent, high pressure sodium (HPS), and metal halide (MH).

High pressure sodium and metal halide are High Intensity Discharge (HID) lights. HID lights are generally for more serious gardeners; the initial cost is high, but it is well worth it. Imagine being able to grow almost anything you want indoors or on your balcony!!

A few things you should consider when deciding whether to invest in a grow light are: Type of plants, square footage, initial cost, operating cost, life of bulb or system, and aesthetics.

A general rule of thumb is that each square foot should receive between 1,000 - 3,000 lumens. Typically, the cheaper the initial cost, the more expensive the operating cost and vice versa.

Here's a summary of the four types of bulbs:

Incandescent SpectrumLifetime of bulbEnergy Efficiency (Wattage to Lumens)
varies 750 -1500 hours 75 W, 1165
Special Qualities: Produces a lot of heat, doesn't last very long, expensive to maintain, not a very energy efficient, but cheap initial cost. Hey, at least it's a grow light.
Fluorescent SpectrumLifetime of bulbEnergy Efficiency (Wattage to Lumens)
varies 10,000 - 20,000 hours 18W, 1,100
4' 40W, 2,960
8' 75W 5,800
Special Qualities: Fluorescent light is widely dispersed, which means that you have to have them very close to the plant (2") in order for them to be effective. This is sometimes unattractive and bothersome because if your plants grow fast, you have to readjust the height often. Used mostly for sprouting. Available in cool white and full spectrum.
High Pressure Sodium SpectrumLifetime of bulbEnergy Efficiency (Wattage to Lumens)
Red-Orange Yellow 24,000 hours 150 W, 16,000
250 W, 28,500
Special Qualities: If you want a lot of fruit and vegetables and don't mind if your plants look a bit strung out, use HPS. Maybe marry a HPS to a fluorescent for a full spectrum to help you plant relax a bit. High Pressure Sodium lamps are available in 50, 75, 150, 400 and 1000 watt sizes.
Metal Halide SpectrumLifetime of bulbEnergy Efficiency (Wattage to Lumens)
Full Spectrum, Bluish hue 10,000 hours 175 W, 13,000
250 W, 20,500
Special Qualities: For the natural look and natural speed of things, use metal halide. Metal Halide lamps are available in 175, 200, 400 and 1000 watt sizes. Hopefully they will soon come in smaller watt sizes so that they can be incorporated into small space gardens. Often used in stadiums and photo-shoots, metal halide provide aesthetically pleasing natural lighting for indoors and outdoors.

With grow lights you can permanently garden like it's summer and harvest like it's fall anytime, anywhere. So, lighten up, brighten up, and smile. You can have a healthy, attractive garden anywhere.