Wait until the zinnia flowers are fully dry and faded on the plant
Choose the largest, healthiest flower heads for seed collection
Cut the dried flower heads from the plant
Place the flower heads in a paper bag or on a dry surface
Break apart the dried flower head gently with your fingers
Remove the seeds from the petals and chaff
Separate the plump, dark seeds from the thin, light debris
Let the seeds dry completely for several days
Store the seeds in a labeled paper envelope or airtight container
Keep the stored seeds in a cool, dry, dark place