Sprouting your carrots seeds offers the advantage of giving you a head start with your planting, particularly if you're located in a short growing season area. Start them about the same time as the last predicted frost date for your area, when the lilacs begin to produce foliage. Plant a fresh batch every two weeks from mid-spring throughout the summer to guarantee yourself a continuous supply of tasty, nutritious carrots.
Pour your carrot seeds into a container of warm water and soak them overnight. Prepare a seed-starting flat while the seeds are soaking. Cut the top off of an empty Styrofoam egg carton and set it aside to use as a convenient tray for the flat. Poke four holes in the bottom of each cell of the carton with a toothpick.
Fill the cells up to ¼ inch from their tops with soil-less seed-starting mix. Set the flat in a shallow container of warm water until the surface of the mix feels moist, but not soggy or wet. Remove it from the water and allow it to drain for about two hours.
Sow two or three carrot seeds ½ inch apart in each cell of the flat. Touch a moistened toothpick to a tiny seed and rub it into place on top of the mix. Cover them with 1/8 inch of the soil-less mix. Fill a repurposed plastic spray bottle with water. Spritz the mix with enough water to evenly moisten the surface.
Set the seeds flat into the tray and close everything up in a clear plastic bag. This will help retain necessary moisture and humidity. Use a toothpick to poke 10 or 12 small holes in the bag to allow for air circulation.
Place the seed flat in a warm, brightly lit spot. The top of your refrigerator or above a hot water heater are good locations. Your carrot seeds will sprout in 10 to 20 days.
Check the seed-starting mix every day to make sure that it doesn't dry out. The surface should remain evenly moist but not soggy or wet at all times. Remove the plastic bag for good when your carrot seeds sprout and move the flat to a bright, warm windowsill out of direct sun.
Thin the seedlings when they're about 1 inch tall. Choose the most robust in each cell and cut the others off at the soil line with scissors. Scoop with a spoon each carrot seedling out of its egg carton cell for planting.