Ask a Master Gardener: Indoor seedlings need extra light, not much fertilizer
Q: I bought some flower seeds that said on the package that I should start them indoors in a sunny window. They’ve gotten spindly and don’t look good. Do I need to give them more fertilizer?
A: It’s easy to start seeds indoors, but a sunny window usually doesn’t provide enough light, and then seedlings get leggy and weak. You need to provide some artificial light. But there’s no need to buy expensive grow lights. You can use any fluorescent light fixture with two “cool white” or one cool and one warm white bulb. The light should be within two or three inches of the plants, so it helps to hang your lights on chains that can be shortened as the plants grow. Seedlings need some darkness, too. You can use an inexpensive timer to shut them off for 8 hours a day.
It’s possible you’re fertilizing too much, rather than too little. Too much fertilizer can make seedlings leggy. Once a week, at half strength, should do it. Seedlings shouldn’t be fertilized at all until they have some true leaves (the first “leaves” that appear when the plant emerges are not really leaves at all). So wait at least a week after they come up to fertilize, and don’t use a potting mix with fertilizer in it. A sterile soil-free mix is better.
It’s not too late to start some other seeds this year, depending on what plant you choose. Try some marigolds, sunflowers or zinnias, or herbs such as sweet basil or oregano.
Find more information on seed starting from University of Minnesota Extension online: www.extension.umn .edu/distribution/horticulture/m1245.html.