Gather seeds from dandelions once they dry out and attain their characteristic globular appearance. Place a plastic bag over the seed head. Hold the bag closed and shake the stem to release the fluffy white seeds.
Pour the seeds into a shallow bowl. Mist the seeds to weigh down the cottony matrix so they will not blow away and germinate in undesirable areas.
Prepare a growing container for the dandelion seeds. Fill a 3-inch-deep seedling tray with organic potting soil. Mist the soil with a spray bottle until it feels wet at a depth of 1 inch.
Sow one dandelion seed per square inch of surface area in the seedling tray. Press the dandelion seeds firmly into the surface of the soil to secure them. Sprinkle a very light layer of sharp sand over the dandelion seeds to hold moisture around them as they germinate.
Set the seedling tray next to a south-facing window or under a fluorescent lamp. Keep temperatures at about 68 degrees F.
Watch for germination in two to three days. Thin the seedlings so one remains for every 4 square inches of space. Mist the dandelion seedlings every other day to maintain light dampness 1/2 inch below the surface.
Harvest the greens by clipping them near the base instead of pulling up the whole plant since they will continue to generate leaves during the growing season.
Clip off the flower heads as they appear, or let one or two ripen so you can harvest more seed.