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Farmers Almanac
The 2014 Farmers Almanac
Farmers' Almanac

Choosing a Grow Light

Choosing a Grow Light

If you plan to start seedlings indoors this winter, providing enough light is crucial to preventing them from stretching and weakening. Choosing the right grow light can be the key to healthy, sturdy plants.

While incandescent light fixtures are reasonably priced, the cost of keeping them lit can be a burden, and the bulbs burn out quickly. Incandescent bulbs may generate too much heat to be good for your young plants, and they do not emit a broad spectrum of the light needed for your plants to thrive.

Available at any hardware store, fluorescent lights are relatively inexpensive to run, although the start-up cost for the fixture and the bulbs can be high. As well, some fluorescent light fixtures must be wired into the electrical system of your home, which will require the assistance of a certified electrician. Stand-alone fixtures also exist, which can be moved from room to room. Unfortunately, although regular fluorescent lights do not run as hot as incandescent bulbs, they still do not have a good range of the infrared light that is required by plants. You can easily remedy this by purchasing light bulbs specifically designed with the appropriate light spectrum required by plants.

Grow light fixtures are available in many designs, from plug-in fixtures that you can suspend with wire or chain above your seedlings, to portable stands with built-in lights and a tray for your plants at the base. Some models will have more than one bulb, which increases the amount of light that reaches your seedlings. Commercial grow lights usually consume the same amount of energy as regular fluorescent fixtures, and they operate within a balanced infrared spectrum that is ideal for plants.

LED lights are yet another option for gardeners: the initial purchase of the fixture and bulbs will make a dent in your wallet (although the cost is decreasing as more LED products become available) but the bulbs will last significantly longer than their incandescent or fluorescent counterparts, and are far cheaper to run for long periods of time. Make sure you purchase LED bulbs designed as grow lights for plants. Hardware and pet supply stores, and garden centers may offer LED fixtures for sale.

Of course, if you have a sunny windowsill to start your seeds in, that’s the best kind of “grow light”: sunshine doesn’t cost a cent (and it’s hopefully plentiful)! Remember that window glass can reflect sunlight back onto your plants and create a heat zone that your young plants may not be able to handle, particularly if they are covered. Monitor your seedlings for the symptoms of heat stress, which may include wilting, scorching, and yellowing or browning of the leaves. Also be on the lookout for windows that are not sealed properly, creating a chilly draft that your seedlings cannot tolerate.

The way light spreads out from the bulb and how much of it covers your plants is called the beam angle. The wider the beam angle, the more light reaches your seedlings to promote better photosynthesis and growth. Many commercially-available grow lights have attached reflectors to widen the beam angle. Adding extra bulbs will also increase coverage.

Your grow light should be mounted so that the height is fully adjustable. Place the light 1 to 2 inches above your seedlings. Do not allow the bulb touch the plants. As the plants grow, raise the level of the light accordingly. The light should be kept at maximum intensity for 12 to 16 hours each day to keep the seedlings from becoming spindly. Set up the light on a timer so you don’t have to remember to turn it on and off.

The quality of light emitted by your grow light bulbs will diminish with use, and the benefits to your plants will be lost. Do not wait for the bulbs to burn out before replacing.

3 comments

1 gardenmouse { 03.11.14 at 1:00 pm }

I have an indoor greenhouse (received as gift) to start plants..should I use a grow light with it? sun not great from my windows

2 CAPERNIUS { 02.20.14 at 2:00 pm }

I did not know there were many different types, or grades, of plant “grow lights”.
I always thought that they were all the same, save for product “A” is better built than product “B”….
Commercial grow lights? what are some reputable companies to do business with?
and what are some things to look for? I would hate to spend big bucks on a piece of junk….

3 Staci Smith { 02.19.14 at 9:37 am }

I am currently sowing Hungarian Pepper seeds, indoors. I have a garden window to allow sunshine and have chosen not to install artificial light. To spring!

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