Best Grow Lights for Seed Starting

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The T8 and T5 bulbs offer a more efficient light source for your growing plants.

Suitable supplemental lighting is better for starting seeds than the light coming through most windows. A setup of lights will allow you to grow a much wider range of vegetable cultivars, which will make your garden even more interesting. Until recently, most seed starters used inexpensive fluorescent T12 shop lights, with the height of the lights adjusted so the plants were very close to the bulbs — within 1/2  inch for full-sun plants, such as tomatoes and peppers.

But two new and better choices, T8 and T5 bulbs, are now available. In fluorescent light lingo, the “T” stands for “tube,” and the number represents the bulb’s diameter. Old-line T12 fluorescent bulbs are still cheap and easy to find, but for a few dollars more per bulb, you could upgrade to more slender T8 bulbs, which are up to 40 percent more efficient. Plants get plenty of light when grown within 2 inches beneath T8 bulbs. You can usually find a 4-foot-long, Energy Star-certified, two-bulb T8 fixture at retail stores for about $20, plus another $10 for the bulbs.

Many garden supply stores now offer grow lights that use even skinnier T5 bulbs, sometimes called “high output” (HO) fluorescents. Less glass is required in their manufacturing, and T5 bulbs are 9 percent more efficient than T8 bulbs and 51 percent more efficient than the old T12s. While T5s are some of the best grow lights for starting seeds indoors, as they set the standard for light output and energy efficiency, they may be glaringly bright if not equipped with a reflective hood. Plant height must be closely monitored, too, with no less than 3 inches of space between the bulbs and the tops of the plants. Some people find the narrow T5 bulbs too delicate to handle in 4-foot lengths, and instead choose shorter, 2-foot bulbs. 

— Barbara Pleasant, gardener, writer for Mother Earth News, and author of several books, including Homegrown Pantry.


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Mother Earth Gardener
Mother Earth Gardener
Expert advice on all aspects of growing.