In an effort to improve seedling production in the spring, you might consider moving your seedlings from a sunny window (that may or may not be sunny every day) to an area where you can install fluorescent lights. Moving seedlings into an environment where the light can be controlled, and the day and night temperatures won’t fluctuate wildly, cries out for a heated basement. Even the sunniest windows rarely offer more than a few hours of really bright light each day, and that doesn’t count the losses because of cloudy days or a light covering of dust or dirt on the window glass.
But even with the fluorescent lights on for 18 hours, seedlings don’t really get enough light. While a fluorescent light looks bright to us, it is a poor substitute to a seedling expecting to bask in the sun. To provide enough light, use two 4-foot-long, two-bulb shop fixtures (available at any hardware store), suspended just 2 to 6 inches above the seedlings.
Special grow lights aren’t magic. Often, there is just a blue coating on the inside of the tube. The overall amount of light is reduced, and the seedlings think they have sunglasses on. A mix of warm white and cool white tubes will give the right kind of light, and more of it.
A small fan is needed nearby to move the air, helping to prevent fungus diseases and to flex those little seedling stems, enabling them to grow stronger and thicker (just like going to the gym). But don’t get carried away trying to make little Arnold Schwarzenpeppers.
Most seedlings like it comfy — temperatures in the 60s and room to grow. If they are too crowded, or if that furnace is overheating them, they will become stretched and spindly. Perhaps they are trying to grow up quickly and get away!
Buy your seeds early while there are lots of choices, but don’t start them too early. Look on each package for the right timing, and mark your calendar.
Earlier posts on seed starting: