Zinnias are among the easiest flowers to save seeds from, and they, like many annuals, produce a good number of seeds per plant. There are a few things to keep in mind before you try to save seeds, though:
Only save seeds from open-pollinated varieties. There are some hybrid zinnia varieties out there (the "Zowie" and "Profusion" lines of zinnias come to mind), and those will not grow true from seed. There are plenty of heirloom varieties, though, that you can save seed from and grow year after year.
You will have to put up with some unsightliness; spent zinnia flowers can be on the ugly side. The only way to get seeds is to let the pods dry on the plant. The good news is that a few blooms are all it takes to have enough seed for next year. You can deadhead the rest when they start to look tired. If you have a large bed, try to save seeds from plants away from the edge of the bed so the spent flowers are less noticeable.
Try to save seeds from those plants that display qualities you enjoy. Maybe the bloom color is absolutely perfect, or the height of the plant is just what you were looking for. Saving seeds from the best plants is the best way to end up with beautiful blooms next year.
How to Save Zinnia Seeds
Allow the flower head to dry completely on the plant; it will be dark brown and dry when it is ready to harvest. Trying to harvest the seedhead too early will result in immature seeds, which will not germinate.
Once your seedhead is dry, cut or pull it off of the plant. Then, simply pull it apart or rub it between your two hands to release the seeds. It is best to do this over a container of some kind to catch the seeds.
Speaking of the seeds, zinnia seeds can be difficult to see. If you look at the seedhead you've taken apart, you'll see dried petals. At the base of those petals is an arrow-shaped base; these are the seeds.
Storing Zinnia Seeds
Once you've collected your seeds, store them in a container or bag in a cool, dry place. A refrigerator is ideal. If you don't have the time or inclination to separate the seedheads into individual seeds at the time you collect them, you can even store the entire dried seedhead, then just crumple it apart and sow the seeds in the spring, after danger of frost has passed. There are plenty of old-time gardeners who do it this way.
The following zinnia varieties are open-pollinated, meaning that they will grow true (look and grow the same) from seeds saved from your garden.
- 'Green Envy'
- 'Bright Jewels'
- 'Canary Bird'
- 'Candy Cane'
- 'California Giant'
- 'Lilac Queen'
- 'Miss Wilmott'
- 'Persian Carpet'
- 'State Fair Mix'
- 'Cut n Come Again'