Easy way to grow green onions is to buy them at the grocery store, chop off the roots with about a quarter to a half inch of the onion, then use the tops for supper.
Take the root ends and plant them barely under the soil. You can plant some seed with them if there’s enough space between them. They’ll start growing again immediately. You’ll have green onions much quicker than by seed...by the time you have used the new growth on the root ends you planted, the seeds you sowed will have sprouted and grown big enough to use, and your original root-end stock will probably have sent up stalks to flower and seed; ...
Celery works great this way too.