Plant Grow Lights

February 28, 2006

The wide variety of styles in plant grow lights can cause confusion when it’s time to select the proper grow lights to use for raising vegetable seedlings indoors.

My first choice in grow lights for nurturing young seedlings remains the good old fluorescent light bulbs. You can make do with the standard tubes, but for the best results purchase the fluorescent grow lights that are specially designed for growing plants.

Types of Plant Grow Lights

You may have come across spot light or bulb styled grow lights that fit standard sized light fixtures. These are great for providing additional light to houseplants, but they don’t distribute enough light over a wide enough area to use them effectively for seed starting.

Metal Halide, High Pressure Sodium, HID, Mercury Vapor, and the newer LED bulbs are all commonly used by professional growers and by serious hydroponic gardeners. These plant grow lights are designed to generate sufficient light output to grow plants to maturity and to even induce flowering and fruiting with no direct sunlight. But they’re overkill for basic seed starting purposes in the home, not to mention the high costs to purchase and operate them.

Fluorescent Grow Tubes

Fluorescent grow lights are convenient, relatively inexpensive, long lasting, and less expensive to operate. They are manufactured to produce close to the full spectrum of light output, which ensures that your plants’ light requirements will be met.

The fluorescent grow tubes can be used in simple shop lights or you can build a plant light stand or purchase a light cart that will make it a snap to grow a large number of transplants in a small area. The grow light systems are also designed to make it easy to adjust the height of the grow lights as the plants grow taller.

With average use you can expect your fluorescent grow lights to easily last for four or five years. Some grow lights produce a wider spectrum of light so check the listed light output and expected life before making your purchase.

Using Standard Tubes Instead of Grow Lights

Of course you can use standard fluorescent tubes for starting seedlings indoors, but your plants won’t receive the wider spectrum of light that they would enjoy if grown under the tubes that are designed to promote plant growth.

If you do decide to use the standard type of fluorescent tubes; mix one cool tube along with one warm tube in each light fixture to get a better mix of light output for those growing vegetable transplants.

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  • Callie Works

    What a coincidence — I installed a new set of grow lights this afternoon! I bought an inexpensive shop light fixture from Home Depot and fitted it with 48′ flourescent tubes. I’ve read varying recommendations for the height of the light from the seedlings. What do you recommend?

  • It must be a case of great minds thinking alike. Almost the same moment, I posted about my grow light solution.

  • Kenny Point

    Callie, I keep my fluorescent grow lights pretty close, maybe three inches above the tops of the seedlings. Optimum height can vary depending on the type of plants, and the brand or power of your grow lights. That’s probably why you’re seeing different recommendations, they’re all based on various types of grow lights. Watch the results that you get and experiment with different heights until you discover what’s best in your particular situation. For example, if you notice that your plants are growing too tall and lanky, move the grow lights closer to promote stockier growth.

  • Kenny Point

    Patrick, I really like your solution, but I still love my grow light cart.

  • David Smith

    When starting vegetable seedlings, how many hours per day should you leave fluorescent lights on?

  • Kenny Point

    David, for vegetable seedlings that will be transplanted outdoors you should provide about 12 to 14 hours of light per day.

  • PJ

    Great minds sure do think a like. Has anyone played with any Led Growing Lights yet?

  • stevie b

    Can someone tell me what heights to set the grow lights at for seedlings?

  • Kenny Point

    Hi Stevie, I set my lights pretty close, about an inch or two above the seedlings, and I raise the lights as the plants grow. If your seedlings grow leggy and spindly your lights are not close enough or they are not providing enough light to the plants.

  • tanya

    i have been experimenting with indoor grow lights and have run into some problems. last month i tried some lettuce for winter eating. the seeds sprouted within 3 days (without extra light). i have a 2 bulb/4 ft system which gives me some grief.
    if i put the light very close to the seedlings, then only the plants directly under the light are affected. the plants to the outside of the light fixture receive no benefit and and are leggy and weak. the ones under the light are not much better.

    the lamp is about 3-4″ above the seedlings. by now i should be able to pick some lettuce, but the plants are very small and just beginning to put out true leaves.

    another problem i had last spring is that several seedlings did not grow at all. my tomato plants and collards, for example, did very well but even too quickly. beets on the other hand sprouted very quickly and NEVER set true leaves.

    it seems there are some guidelines that i need to know but cannot seem to find anywheres. any advice/info?

  • Kenny Point

    Hi Tanya, I have a similar light setup and experience the same thing with seedlings growing along the edges of the trays under the lights. I place my seedlings closer and also turn my seedling flats lengthwise under the grow lights so that more of the plants receive light from the central area of the grow tubes. It reduces the number of seedlings that you can start but the seem to grow better and stockier. That’s one of the advantages of the four tube fixtures. I don’t know what the problem was with your beet seedlings. Did you feed the lettuce plants at all? The rapid and weak growth for the tomatoes and collards definitely sounds like they were not getting enough light. I would try again with all of the plants and experiment with setting the lights closer or even try a different brand of lights.

  • tanay marquette


    Did not feed the seedlings. The new soil this winter is a good growing soil but i may add some fish fertilizer and/or kelp to the water now, after 4 weeks.

    What i am getting is the old saying that you get what you pay for so i need to save up for a better system. I did price out a 4 bulb light online but it was so expensive that i held off buying it now. But that will be the solution.

    As for bulbs, are there some brands or wattage that are better to buy?

  • Kenny Point

    I’m happy with my light cart even though I have the two tube light fixtures and I’m sure there’s also a trade off with more electricity usage with four tubes, not to mention the higher initial cost that you noted. I’ve used different bulbs and can’t say that I have a favorite. I usually mix it up and even combine different brands in the same fixtures. I spend a little extra to purchase the “grow” type tubes even though many indoor seed starters say they don’t matter and seem to raise decent seedlings using the ordinary florescent tubes.

  • Pingback: Grow Lights Make Your Plants Grow!()

  • Led lights are great because they are long lasting and consumes less electricity.,:”

  • I always start my tomato seedlings under the 4′ double fluorescent fixtures from home depot for under $10 each. I placed hooks in the ceiling and chained the lights with enough chain to lower the the lights down to within a few inches of the plants. I had great success with using just the cool white tubes. Compact fluorescent lights work great too and are really cheap to run too. I will soon experiment with LED. Great site Kenny. I’m glad I found it.

  • Matthew

    Which indoor lighting (hps, ml) is best for a laurel tree? Thanks 🙂

  • High Output fluorescent tubes are more energy efficient than regular fluorescents and for best efficiency you should use T5 tubes!

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