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 away some as gifts.
Before you begin, it's important to know whether your zinnias are open-pollinated plants or hybrids. Seeds from hybrid plants typically do not come true to the parent plant, so if you love a specific attribute of the zinnia, such as its double flowers or special colorings, you might be disappointed by the offspring of hybrid zinnias. Seeds from open-pollinated plants, though, will grow true to the parent plant, so it makes sense to harvest those seeds.
However, seed saving requires a little planning if you want to make sure that your open-pollinated seeds remain pure, since zinnias can be cross-pollinated by insects from different varieties. If you have a lot of space--like a farm--plant one variety per half-mile. For most of us, though, that's not feasible. Instead, bag or cage several flower buds before they bloom to prevent accidental cross-pollination. Leave the bag on until the flower is done blooming.
You will have to put up with some unsightliness as you wait for the flowers to dry on your plants, but that's how you allow the seeds to ripen. Make sure to select plants that are healthy--powdery mildew can transfer to seeds, so don't save seeds from plants with disease. The good news is for an average-size garden, you will generally only need a few blooms' worth of seeds to have enough to plant the next year. You can remove the rest of the flowers before they turn unsightly. Moreover, if you have a large garden bed, you can opt to save seeds from plants away from the edge of the bed, so the drying flowers are less noticeable.
Aim to save seeds from plants that display qualities you enjoy, such as an ideal bloom color or optimal plant height. The following zinnia varieties are open pollinated, meaning they will grow to look the same as the parent plants from which their seeds came:
- 'Green Envy'
- 'Cactus Bright Jewels'
- 'Canary Bird'
- 'Candy Cane'
- 'California Giant'
- 'State Fair Mix'
- 'Cut n Come Again'
- 'Red Spider'
- 'Jazzy Mix'
Equipment / Tools
- Basket or other container for harvesting flowers
- Pruners (optional)
- Writing utensil
- Zinnia plants
- Paper towels
- Glass jar with lid
Wait for the Zinnia Flowers to Dry Before Harvesting
Allow the zinnia flower heads to dry completely on the plant. Each flower will be dark brown and dry to the touch when it is ready to harvest. Trying to harvest a flower too early will result in immature seeds that won't germinate.Once the zinnia flowers are dry, cut or pull them off the plant. Make sure to keep varieties separated and labeled, unless you don't mind a mix full of surprises! Also, avoid watering the flower bed before harvesting seeds, or the seed heads will need more time to dry. Place the harvested seed heads on a screen so that they dry thoroughly on all sides. This may take up to a week, depending on the seed head and moisture level.
Release the Zinnia Seeds
Spread some paper towels over a clean, flat surface where you can work to gather the seeds. Place a paper plate on the area, and label the variety name directly on the plate with a marker.
Take a dry zinnia flower, and "flail" the seed head--hit it gently to release the seeds, or pull it apart or rub it between your fingers over the paper plate to release the seeds. The seeds are small and arrow-shaped. Some might still be attached to the base of a petal. If that’s the case, gently pull off the seed. Repeat this process with all of your dried flowers, discarding the petals and only keeping the seeds. Keep the varieties separate.
Let the Seeds Dry
Spread out the seeds and let them air dry uncovered for a few days. This will help to prevent them from rotting or molding in storage.
Store the Zinnia Seeds
After the seeds have dried, place them in a paper envelope or bag for storage. If you have multiple zinnia varieties, use separate envelopes for their seeds unless you don't mind mixing them in your garden. Label each envelope, so you remember what's in it.
Then, place the seed envelope in a lidded glass jar, and store it in a cool, dry place out of direct sun. A closet is ideal. Once the danger of frost has passed for the next growing season, you can sow your seeds outdoors. For best results, aim to use your seeds within three to five years.