Harvesting zinnia seeds is a very straightforward process. Getting the right seeds that produce predictable, true-to-color blooms is a bit more challenging.
This article covers the best tactics to get a lifetime of quality zinnia seeds.
Keep reading to learn tricks to simplify controlled zinnia pollination. In no time, you will understand how to harvest zinnia seeds that will provide vibrant, beautiful flowers for years.
Harvesting Zinnia Seeds: A Genetics Primer
Zinnia care is easy even for the most inexperienced gardeners. That is why these hardy flowers are so prevalent in backyard gardens.
If you can dedicate the time to hand-pollinating, you can grow beautiful flowers from zinnia seeds year after year.
Are you starting with many varieties of open-pollinated zinnia plants? In this case, you must carefully control reproduction if you want consistent flower production.
When you let zinnias reproduce naturally, the resulting seeds may not grow to resemble the parent plant. This is because insects don’t discriminate between different zinnia varieties when pollinating these gorgeous flowers.
If you want to keep growing your favorite zinnia flower variety, you need to control the pollination process.
Saving seeds allows you to grow beautiful zinnias from seed for free each year. Strategic pollination ensures the quality of these precious seeds.
How to Harvest Zinnia Seeds from Open-Pollinated Plants
Open-pollinated zinnias inherit genetics from two parent plants. By ensuring that the flowers that breed are of the same variety, the seeds will grow to produce true-to-color flowers.
One packet of zinnia seeds can last forever when you correctly understand how to cross-pollinate zinnias. You will have a lifetime of reliable, beautiful blooms.
Step 1: Isolate Zinnia Variety Flowers
To prevent different types of zinnia plants from cross-pollinating, you must ensure that varieties are separated.
This generally involves planting different zinnia varieties in separate greenhouses on commercial flower farms. You could also sow zinnia seeds at staggered times or in fields spaced hundreds of yards apart.
The easiest way to control pollination is by caging flowers once they start to bud. This enables you to hand-pollinate the best blooms, ensuring the right genes get passed down.
You should only harvest zinnia seeds from healthy flowers on robust plants free from obvious signs of disease. Look for strong, sturdy stems and bright, turgid foliage.
You should also consider which colors you want to continue growing. Examine each plant to see which ones are producing the most beautiful flowers.
Enclose immature flower buds on these plants in small bags. Alternatively, you can cage entire zinnia plants with pollen-blocking fabric.
Step 2: Hand-Pollinate Zinnia Flowers
Once you have your choice flowers fully enclosed, they will be unable to cross-pollinate on their own.
Zinnias usually rely on insect pollinators like bees to spread pollen motes. You must replicate this natural pollination process by hand.
Use a clean paintbrush or cotton swab to gather pollen gently from among the flower petals. Take this pollen-saturated brush and repeat the swabbing for all plants from the desired seed variety.
Keep in mind that zinnia flowers produce seeds throughout the full bloom. This is because zinnias are actually compound flowers comprised of dozens of tiny florets.
If you want to harvest zinnia seeds throughout the entire flower head, be sure to pollinate all the florets. It might take some extra time, but doing so can nearly double the seed yield per plant.
Use sterile, separate utensils to pollinate each zinnia variety. You want to minimize the risk of introducing pollen from other types as this could impact the seeds produced.
Let the pollinated flowers mature in their enclosures until they go to seed. Once the flowers fully bloom and begin to lose their bright colors, you can remove the bags.
Step 3: Allow Flower Heads to Mature
If you want viable seeds, you must wait to harvest zinnia flowers until they are fully mature. Harvesting zinnia seeds too early will leave you with sterile, underdeveloped seeds that won’t germinate.
Brown flowers are a good indicator that zinnia seeds are nearing harvest time. Still, always look for additional signs of maturity before clipping the seed heads.
When seed heads start to get dry and crunchy, they are likely ready to collect.
Check the color of visible seeds before harvesting zinnia flower heads. Mature seeds are dark brown, while immature seeds still have some green coloring.
Step 4: Deadhead Ripe Zinnia Flowers
Saving zinnia seeds from vigorous plants increases the likelihood that the offspring will be healthy as well. Trim your favorite flowers from healthy plants only.
A single zinnia flower produces a lot of seeds, so you won’t need to collect too many pods. Still, be sure to collect zinnia seeds of the same variety from a few different plants to promote genetic diversity.
You can cut as many seed pods as you want since new flowers will grow to replace the deadheaded zinnias. This makes zinnia seeds (and flowers) a fantastic option for gifting, as you will have plenty to spare.
Step 5: Dry Zinnia Flowers
Mold-causing moisture is dangerous for any seed. Powdery mildew on zinnia flowers can get passed down to offspring.
You must protect these precious seeds from high moisture levels and halt the growth of dangerous bacteria and fungi.
The flower buds should be completely dry before you remove the seeds. Allowing the dry seed heads to sit in a full-sun location reduces the risk of moisture retention.
The UV rays can also destroy some of the harmful microbes that might be clinging to the seed pods.
Lay the flower heads on a paper towel and place them in a well-ventilated spot that receives direct sunlight. Leave them for a few days or until the plant matter crumbles away when you touch it.
Step 6: Thresh Flower Heads
It doesn’t need to be a challenge to separate seeds from plants. As long as you have a solid surface and some elbow grease, you can thresh the flower stalks.
You must break up the dry plant material, so it is easier to sift out the seeds. Do this by grabbing a handful of flower stalks and striking the seed heads on a solid surface.
You might consider placing the flowers in bags before you thresh them. This makes the process cleaner, but you won’t have the benefit of a breeze to carry away the chaff.
You can leave the bran on, but this increases the risk of spoilage if the seeds are improperly stored. Remove the seed coats by rubbing them between your fingers if you want to keep the seeds for more than one season.
Step 7: Dry Zinnia Seeds
Effective seed saving comes down to minimizing the moisture your seeds get exposed to.
Even though you’ve already dried the seed heads, you’ll also want to dry the seeds. Ensuring they are bone-dry reduces the risk of mold-causing moisture retention.
Spread the seeds evenly on a paper plate or cookie sheet and set them in a sunny spot.
Once they are dry, saving zinnia seeds in paper envelopes is an ideal way to store them for a few years. Place the seed envelopes in a dark, dry location that stays cooler than 65 degrees Fahrenheit.
How to Harvest Zinnia Seeds from Hybrid Plants
Harvesting zinnia seeds from hybrid flowers involves letting the flowers die and dry. You don’t need to pollinate hybrid varieties.
Still, if you want predictable zinnia flowers, you might be disappointed by hybrids. These zinnia varieties are not true-to-parent, so they are unlikely to be as vibrant as open-pollinated types.
Where to Buy Zinnia Seeds
Zinnias are widely popular across the nation. It’s easy to find your favorite zinnia flowers in person or online. Still, you must look for open-pollinated flowers if you want to harvest zinnia seeds.
The Dreamland Zinnia produces gentle pastel-colored flowers that give your flower beds a fairytale feel
If you like brighter colors, you can’t go wrong with the vibrant Dahlia Flowered Mix.
Are you building bouquets with your zinnias? If so, you might enjoy adding some unique zinnia varieties like the Swizzle Series and Cactus Zinnia.
When can you harvest zinnia seeds?
Brown flowers are a good indicator of maturity but always check for additional signs first. The flower must be dry and crispy before you clip it.
Inspect the dried-out flower heads for green seeds before harvesting. Green zinnia seeds are immature, and they will not germinate.
Zinnia flowers with green seeds must be left to mature a bit longer on the stalk.
How do you separate zinnia seeds from the chaff?
Threshing involves simply striking the dry zinnia flower against a solid surface. This is the most straightforward method of collecting seeds from zinnias.
Historically this involved threshing the stalks against the floor of a barn. The heavy seeds then separated from the lightweight plant material and settled on the floor.
The chaff could then be swept away or carried out by drafts. Small pieces of wood called thresholds secured to the doorways of the barn kept the seeds inside.
Do zinnias come back every year?
Zinnias are true annuals, meaning they complete their life cycles in one growing season. This doesn’t mean they won’t emerge next year, though!
Growing beautiful zinnias with predictable, vibrant colors involves a bit of work. However, zinnias are prolific plants that produce many seeds.
If these annual flowers are left alone with no intervention, they will cross-pollinate and go to seed. Some of the seeds dropped will survive over the winter and spring up in spring.
The resulting flowers will not be consistent in color and might not pop up where you want them to.
If an untamed garden full of flowers is your style, you might enjoy letting these beautiful blooms run rampant.
What part of the zinnia flower is the seed?
The bristly flower centers of zinnias are packed with seeds, much like the brown center of a sunflower.
Also, like sunflowers, zinnias produce two sets of floret seeds in the inner and outer petals. Seeds that develop in both areas are viable if you pollinate them.
Still, you might have better luck with seeds collected from the center. Anecdotal evidence suggests that these inner seeds germinate more reliably.
How long do dried zinnia seeds last?
Dried zinnia seeds can last decades when stored properly. Enclose seeds in a paper envelope in a dry location, or secure them in a glass jar with a tight-fitting lid.
If you opt to store the seeds sealed, you should add a desiccant sachet to the container. Silica gel packs or ceramic disks help control humidity, extending the life of your seeds.
As with most seeds, they don’t necessarily have an expiration date. Instead, the seed germination rate decreases over time.
After five years, the germination rate begins to drop. If you plant a properly stored 20-year-old zinnia seed, there is still a small chance that the seed will sprout into a healthy plant.
Are zinnia seeds true to color?
As long as you control the pollination of zinnia flowers, the resulting seeds will produce true-to-parent blooms.
This includes passing on more than just beautiful colors. The growth habits of zinnia plants are hereditary, too, so you can ensure that your favorite double flowers keep coming back.
Harvesting Zinnia Seeds Means Years of Enjoyment
Do you want to keep your favorite zinnia flowers adorning your garden for many years? If so, you need to harvest zinnia seeds the right way.
After reading this guide, you should know how to harvest zinnia seeds that produce true-to-parent plants. Interested in more zinnia content? Visit our zinnia page for more growing tips, care guides, bouquet suggestions, and more!
Getting started on your seed growing journey? Use my seed starting guide to find care guides, helpful tips, product suggestions, and more!