Gardening: Grow lights ideal for giving seedlings healthy start

This is the second in my series on starting seeds indoors. This week’s edition is on providing light for your seedlings. Along with water, the right kind and placement of light is a critical element for proper seedling development. To start however, I need to get a bit technical.

If you have grown seedlings in a sunny window, you may have observed that those that require bright light don’t always do well. During our short winter days, they stretch toward the window seeking more light and get spindly. Two factors are at play here. This time of year, we only get eight hours and 47 minutes of daylight. This is about half the 16 hours seedlings need to grow well. Second, the sun is low in the sky now which reduces its intensity. Third, the intensity of the sunlight shining in a window decreases rapidly the further it shines into a room. A rating of “bright sunlight” only goes about 2 to 3 feet into a room before it drops off precipitously. That means your seedlings must be within a couple feet of the window. But that leads to another problem; it can get very cold near windows.

Enter using grow lights to provide artificial light. Lighting technology has changed dramatically in the last 10 years such that we are now using the lumen as a measure of brightness rather that the wattage to express the power of a light. A single lumen is about the brightness of one candle and the increasing brightness can be imagined as the increasing intensity of a rain shower. A tray of seedlings needs about 4,000 lumens to grow well.

The most efficient and cost-effective growing lights today are LEDs or fluorescents, with LEDs quickly taking in the lead and for a good reason; they emit more lumens than other sources, come in a range of colors that can mimic the full spectrum of sunlight and last longer than other types of bulbs. There are other expensive lights out there but for a home grow setup LED or fluorescent 4-foot shop lights work well. These are available at hardware stores for well under $50 for a two-tube fixture. I prefer the ones that have naked tubes, so they give maximum light. Try to get those that are white light or daylight and put out at least 4,000 lumens. A standard 10-inch-by-20-inch planting tray will need two fixtures set within 2 inches of the tops of the seedlings. As the seedlings grow, the lights will need to be raised.

To hang your lights check out this plan from Kansas State University made out of PVC pipe: https://kansashealthyyards.org/component/allvideoshare/video/easy-to-make-a-grow-light?Itemid=101. Another “T” fitting and additional pipes can be added to the top to hold two light fixtures. For larger setups, inexpensive wire racks will hold multiple flats.

Tip of the week: Check your houseplants for water. If the soil is dry down to the first joint on your index finger, its time to water.