Green onions, also called scallions, can be used in salads, meat dishes, soups and stews. Scallions are actually onions harvested while still immature, and they have a milder onion flavor. Start your green onion seeds indoors six to eight weeks before the final frost, especially if you live in a climate with a short growing season, and transplant your onions outdoors once the soil warms up. With a bit of preparation, you'll be able to enjoy fresh green onions throughout the summer.
Mix sterile potting soil with equal parts perlite and vermiculite. Fill your planting tray two-thirds full of the mix. Moisten the potting mix until water starts to leak out the drainage holes at the bottom of the tray.
Sprinkle onion seeds evenly over the surface of the moistened soil. Cover the seeds with a ¼-inch layer of vermiculite.
Water the soil using the finest setting on a spray bottle. Cover the tray with plastic wrap to maintain moisture levels.
Place the planting tray in a sunny window sill. For optimal germination, maintain the room temperature at 75 degrees Fahrenheit. Remove the plastic wrap after your seeds sprout, which should be about one to two weeks.
Keep the soil moist. Dilute liquid fertilizer to half strength and apply it to your seed bed once a week.
Trim back your green onion seedlings to 4 inches any time they begin to droop. Transplant them to a sunny location in your garden or to individual containers once the final threat of frost has passed and the plants are large enough to handle.