Let There Be Plant Light

Gardening

Indoor plant lights let you shine a light where and when the sun don’t shine. They allow you to extend the growing season; have a year-round supply of fresh flowers, healthy vegetables and exotic herbs; as well as give your young seedlings a head start before you can plant them outside.

There are almost as many kinds of grow lights for sale as there are different light spectrums. Everything from a simple $5 incandescent lamp to a sophisticated commercial system using high intensity discharge (HID) lamps can help.

Here’s a rundown on what is available, how much it costs as well as the pro’s and con’s of different types of plant lighting.

Incandescent

Incandescent lamps lay at the low end of the pricing spectrum for plant lights. A good 150 watt bulb will only set you back about $5. You can get such bulbs from a local hardware store or a large nursery. An incandescent lamp can keep a small house plant growing, but isn’t necessarily your best bet for starting a large garden indoors.

Fluorescent

Until recently, fluorescent grow lights had too low an output and were too big and bulky to be of much use except as a grow light for seeds or seedlings. Generally fluorescents are a poor choice for flowering and budding plants because of their low lumen (brightness per unit of energy consumed), but they are a great source for herbs and other plants that don’t need a lot of light. Indoor gardeners most often use the four-foot size. You can purchase the two lamp “shop light” variety for under $40 at your local hardware or garden supply store.

There is big news on the fluorescent light front: new “T5 Lighting Systems” are very efficient and bright and may be better in certain circumstances than the fancier high intensity discharge (HID) lights. T5 fluorescents are more compact and efficient than older forms of fluorescent lighting which allows them to be used for all plants rather than just for seedlings. Key advantages of these high-end fluorescents include: more of their light is used by the plant, they produce less heat than incandescent and HID grow lights and consequently can be placed much closer to the plant.

They are the brightest bulb in the box and very efficient, but expect to pay for the advantages. One 1,000 watt HID lamp can produce the same amount of light as 50 40-watt fluorescent lights.

Within the HID category there are several types of bulbs: High Pressure Sodium, Metal Halide, Low Pressure Sodium and Mercury Vapor. The only ones that indoor gardeners need to concern themselves with are High Pressure Sodium or Metal Halide. They most commonly come in sizes such as 400 and 1,000 watt. The 400 can supply enough light for a growing area of about 15 square feet or a 4 x 4 foot garden. The 1,000 watt lamp can cover an area of about 7 x 7 foot. For fast growth, use about 25 watts of HID light per square foot.

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