Never Pay For Onions Again: Grow Them Indoors! This page has all sorts of interesting ideas for growing plants indoors. I'll give the onions a try right away, and I had planned to do the tomatoes already :)
Add 1 tsp. of liquid food coloring to 1 cup of water. Drizzle the colored water onto the soil surrounding the base of a plant. Wait 24 hours for the water to absorb. Apply another identical dose if the color change was not sufficient.