Tune-Up Your Grow Lights to Boost Seedling Growth

It’s that time of year again, when the days are still short and cold, yet a beacon of light glows in my living room. After months of gathering dust, my plant light shelf is back up and running. In addition to being ready to start seeds of hardy perennial flowers followed by cold hardy vegetables, having grow lights in our living space is a mood booster. Late winter often brings rough weather, which is better in the company of promising little plants.

I have three different types of grow lights, and all require maintenance and fine tuning as the seed-starting season begins.

Fix up Fluorescents

My main indoor growing space is an adjustable four-tiered plant shelf with fluorescent bulbs. The lights are bright enough to grow spring seedlings, but not so bright that they are hard on the eyes. Annual maintenance of the shelf starts with cleaning the trays and hoods with warm, soapy water. I also wipe down bulbs with a soft cloth, because dust can reduce light output and lead to overheating that damages bulbs and ballasts.

A properly functioning fluorescent bulb should immediately pop to full brightness, with no flickering, noticeable delay or dimness. Remove dim or flickering bulbs and look for darkening at the ends, a sign of wear that can indicate stress to the ballasts (the hard-wired end fittings). If installing a fresh bulb doesn’t set things right, you may have a damaged ballast, which can be a costly and complicated repair that is best prevented. Provide ventilation to prevent overheating the ballasts, and avoid excess jiggling of the bulbs, which can damage the delicate connectors.

Maintain LED Grow Lights

If you only use your LED grow lights for a few months each year, they should last forever when stored in a cool, dry place. Keeping them clean is key, which only requires a thorough wiping with a damp cloth. Check the fans in LED units that have them for debris or dead bugs.

I instinctively avert my eyes from looking directly at an LED grow light, as if my brain knows that heavy exposure to blue lights would not be a good thing. It’s easy enough to hold panels at an angle when testing them. Workers in vertical hydroponic production systems wear orange glasses to filter their exposure to blue LED lights.

Failing LED lights may flicker or dim, but usually they simply die. Power surges are a frequent cause of death for LED lights, so use a surge protector whenever possible. Small LED lights consume very little power and can be run from a portable power station, which may be better than tangling with extension cords. If the color or intensity of LED lights bother you, try suspending the light over an opaque plastic bin, and use the bin as your seed-starting space.

Improve Seedling Growth Using Reflective Panels

Indoor container farms use high-output LED lights to produce herbs and salad greens through winter. In these intense systems, it’s worth noting that most of the walls, benches and shelves are white. Dark colours don’t reflect light, metallic surfaces can bounce light in odd directions, but white recirculates light in a gentle, even way.

After noticing that seedlings growing at the ends of my trays struggled for light, I experimented with white reflective panels that bounce light from the overhead fixture into the growing space. Using funky little solar dancers as light intensity indicators, I found that panels made from white paper glued to cardboard clearly increased the light supply to the edges of the tray. A friend uses unpainted white art canvases the same way. The white reflecting panels increase the light plants get from the sides, which leads to more vigorous growth.

In nature, plants get light not only from above, but from diffuse rays reflected from nearby surfaces that reach stems and leaf undersides. Any measures that mimic this pattern are good for plants, and will help you make the most of your grow lights.