Zinnias are among the quickest and easiest flowers from which you can harvest and save seeds. And they produce many seeds per plant, so you shouldn't have to purchase seeds or nursery plants if you want to continue growing zinnias. You also might have enough seeds that you could consider giving some away as gifts. Make sure to select plants that are healthy. For instance, powdery mildew can transfer to seeds, so don't save seeds from plants with disease.
STEP 1: WAIT FOR ZINNIA FLOWERS TO DRY ON THE PLANT
It’s very important to harvest Zinnia seeds at the right time. Waiting too long can cause the seeds to starting rotting or producing mold on the plant; but seeds harvested too early might not be fertile. Plan on harvesting Zinnia flowers when the base of the flower is completely dry and the uppermost petals are almost completely brown. When your flowers are ready; simply cut or pull each one from the plant and place them on a screen or rack to dry. (Using a screen or rack for drying allows air to circulate completely around the flowers during the drying process.)
STEP 2: REMOVE THE SEEDS
When you're ready to harvest the seeds, take a dry flower in your hands and rub it between your fingers, pull it apart, or hit it gently to release the seeds. Zinnia seeds are small, flat, and arrow-shaped and can be found at the base of the petals. If your Zinnia seeds are clinging to the petals, you can gently pull to disengage the two. Repeat this process with all of your dried flowers, keeping the seeds and discarding the petals, stems, and remains of seed heads as you go.
STEP 3: DRY DRY DRY
In order to store Zinnia seeds and to ensure they won’t go bad, they need to be completely dried out. Place seeds on an uncovered paper towel on a counter and allow to air dry. They should be ready to be stored away in about 7 days.
STEP 5: STORAGE
Once your Zinnia seeds are dried out place them in a paper envelope. Paper is ideal for storage as using plastic bags can allow the seeds to retain moisture which will ultimately make the seeds go bad. Don’t forget to label each envelope if you had multiple varieties or colors of Zinnias so you know what to expect next season. These envelopes should be stored in a cool dry place until ready to be planted
