February is the month to begin planting onions. They are quite easy to grow from seeds if you have a sunny window. Get the best potting soil that you can find (ask at your local nursery) and fill the tray about 2/3 full of it. It’s a good idea to blend in some soil amendments like kelp meal or Azomite powder as well.
Place the seeds on the soil and cover with another layer (enough to truly cover the seeds). Onions don’t mind being crowded at this stage so you can sow them rather thickly.
When they sprout, they will look like small blades of grass. Let them go until they exceed about four inches high and then snip them back to that length.
Keep them in the sunny window, but don’t give them any additional light at night. Many onions are day-length sensitive and will put all of their energy into their greens while the days are getting longer. Once the solstice occurs in June, they will begin to form their bulbs.