How to Harvest and Save Seeds From Zinnia Flowers
Are you thinking of collecting your own zinnia seeds so you can propagate them yourself next growing season? While this is possible to do, it takes a bit of skill. In this article, gardening expert and farm owner Taylor Sievers walks through all the steps you'll need to follow to collect and save seeds from your zinnia flowers.
Contents
Who doesn’t love a colorful patch of zinnias alongside a vegetable garden? These easy-to-grow flowers have been a home garden staple for many, many years.
Most people start with a packet of zinnias in a mix of colors. These beautiful flowers come in a multitude of different colors, even in green. If this is where you’ve started, then I’ll wager there’s at least one color in that packet you’ll be dying to keep in your collection for next year.
Or maybe you’re a frugal gardener, and you’re looking to save a few bucks by saving your own seed. Whatever the case, read on to learn more about saving your own zinnia seeds for years to come!
About Zinnia Plants
Zinnias are herbaceous annuals native to Mexico. What does “annual” mean? It means that, as gardeners, we can plant the seed, the plant grows, it produces flowers. It then sets seed before dying after a hard frost in the Fall. Basically, the plant completes its life cycle in one year. This is opposed to biennials or perennials which take 2+ years to complete their life cycles.
Zinnia Flower Anatomy
Another interesting tidbit about zinnias is that the flower you see is actually multiple flowers within one giant composite flower. This is a characteristic of the plant family Asteraceae that zinnias belong to. You’ll find other popular garden flowers, like sunflowers and rudbeckias, in this family, too.
Composite flowers are made up of many disk flowers and ray flowers. Ray flowers are usually the “petals” to our eyes, while the disk flowers make up the center of the flower. Think about the giant brown centers of sunflowers—these are actually hundreds of disk flowers. Sometimes ray flowers are sterile and will not produce seeds. With zinnias, both the disk flowers (the center) and the ray flowers (the petals) will go on to produce seed if pollinated properly.
How to Save Zinnia Seed
Once the petals of your zinnia flowers have begun to die back and the flower head begins to turn brown, you’ll notice when you take your fingers and gently pull apart the flower head that there will be hundreds of thin, flat, brown seeds. These seeds are technically called achenes. An achene is actually a one-seeded fruit.
Congratulations! You’ve collected your first batch of zinnia seeds.
Guidelines for Saving Zinnia Seed
Now, there are a few rules of thumb you want to follow if you’re planning to save seeds every year. These general seed-saving guidelines can be applied to many other plants as well:
Collect Seed From Multiple Plants
The first rule is that you want to save seeds from multiple plants. This ensures that you’ll avoid inbreeding depression, or rather, the loss of vigor within your population due to breeding genetically similar plants.
In other words, the zinnia population you’re producing will have enough genetic diversity that plants and their future progeny will remain vigorous, aesthetically pleasing, and/or fairly resistant to diseases. If you’re only saving seed from one plant, sure there are lots of seeds there, but each year you’ll be decreasing the genetic diversity of your population more and more.
Collect Seed From Healthy Plants
The second rule of thumb is to collect seeds from healthy plants. If your zinnias were riddled with disease or they overall struggled throughout the season, it’s best to not collect seed from those plants. You want to store seed that is disease-free and healthy so that the seeds don’t either rot in storage. You also don’t want the disease doesn’t end up in your zinnia patch the following year.
A great example of a seed-borne disease (i.e. a disease transmitted by infected seed) that affects zinnias is powdery mildew. Powdery mildew is a fungus that appears as a whitish, powdery coating on the leaves, stems, and flowers. Serious infestations will cause the plant to become stunted in growth and may even cause the death of the plant.
Dry Your Seeds Before Storing Them
After you’ve collected your zinnia seed, it’s wise to spread the seeds out on a screen or countertop and let them air dry. Even if it’s been dry outside, you want to ensure that there’s little to no moisture in your seeds. This is critical when you store them.
After they’ve dried for a day or two in a well-ventilated space, pack up your seeds in a paper bag or coin envelope. Make sure to label them with the name of the plant and the date you collected or stored the seeds. Store seeds in a cool, dry, dark place until you’re ready to plant them the next season!
Quick Plant Breeding Facts
So, what if you’re wanting to save seed from a particularly special zinnia plant?
Let’s say you collected seed from a beautiful red flowered zinnia because you want a giant patch of red zinnias in your garden the following year. The next year comes and you plant your seed lovingly into your garden, but much to your dismay, the flower patch is filled with zinnias in a multitude of colors instead of just red. How did this happen?
Zinnias are naturally cross-pollinated by insects. This means that even though the zinnia you collected seed from was red, pollen from a nearby yellow zinnia or pink zinnia could have pollinated your red zinnia as the bees or other insects flitted around your garden.
The study of plant breeding and genetics is a little more complicated than what I’m going to portray here, but essentially just because you collected seed from a particular flower with distinct characteristics does not ensure the seed from that flower will produce plants that are similar.
So, how do you collect and save seeds to select for one color or characteristic?
You’ll need to isolate your zinnias so that you ensure that your zinnia flower will only be pollinated by other zinnias with desired characteristics. There are different types of isolation, and the three methods for isolation are distance, time, or mechanical isolation.
Isolating By Distance or Time
For the home gardener, distance and time isolation may be a little trickier to manage, and it involves careful planning of your garden. Through these methods, you’ll have to make sure that your plants are spaced appropriately to ensure there is no cross-pollination, or you’ll want to plant your zinnias at different times so that they’re not blooming together. Again, you’re likely not a commercial breeder of zinnias, so instead, I would focus on mechanical isolation.
Isolating by Bagging or Caging
Mechanical isolation involves either bagging or caging your flowers to ensure that the right pollen is pollinating your zinnia plant. To cage your zinnia plant, you can simply use a tomato cage or similar structure and place it around your zinnia plant. Cover the entire cage in a lightweight fabric, like tulle or row cover, before the zinnias begin to bloom.
As the flowers bloom, you’ll need to either introduce insects into the cage to pollinate your plant or you’ll need to hand pollinate. Once immature seeds begin to form on your plant, then it’s okay to take the fabric off.
Probably the easiest method for selectively breeding zinnias would be using the bagging technique. Select the flower buds you want to save seeds from and place a small, lightweight bag around the bloom before it opens. You can use lightweight fabric bags, paper bags, or small organza gift bags with drawstrings. Remove the bag briefly to hand pollinate, and then place the bag back on until immature seeds begin to develop.
How to Hand Pollinate Flowers
Pollination of zinnias occurs when pollen from a stamen (male part of the flower) sticks to the legs or body of an insect and is subsequently deposited onto the top of a pistil (female part) as the insect brushes across the stigma (top part of the pistil).
To hand pollinate, you’ll need to mimic this natural process. Using a Q-tip or artist’s paintbrush, wipe the brush across a few stamens, and then touch the pollen-laden paintbrush or Q-tip onto the small, thin, filament-like pistils of the ray flowers or disk flowers. If you’re successful, you’ll notice seeds developing in a few weeks. You’ll need to study the zinnia flower anatomy in order to ensure you are pollinating correctly.
Hybrids Vs. Open-Pollinated Varieties of Zinnia
But wait, there’s more!
Is the zinnia you are saving seed from a hybrid or open-pollinated variety?
You’ll notice on your seed packet that you may be planting hybrid zinnias, which means that two very genetically different individuals were crossed with each other to make this big, beautiful hybrid bloom.
Oftentimes the parents of hybrid plants are pretty sad and ugly looking (or at the very least, nothing impressive) but when they cross-pollinate with each other, their progeny is healthy, big, has some sort of desirable trait(s), and/or is more vigorous. These characteristics are attributed to the phenomenon known as “hybrid vigor.”
Hybrid plants have a vast array of genetic variations, so if you were to save seed from a hybrid plant, the offspring would be highly variable in size, shape, and color. Sure, you can save hybrid seeds, but just note that the resulting plants may not have the desirable characteristics of the parent plant.
Open-pollinated zinnia varieties are either self or cross-pollinated, and their seed will produce true-to-type. This means that most of their offspring will be plants that look relatively the same as the parent plant(s). Open-pollinated varieties are great options for the home gardener looking to save seed from year to year.
Frequently Asked Questions
Can you save zinnia seeds from cut flowers?
More than likely, no. Cut flowers are typically harvested before the seed has set because this is when the blooms are at their peak. You’ll want to wait until the flower-head has faded and begun to turn brown on the plant before harvesting seeds.
Do zinnias reseed themselves?
If you’re a forgetful gardener, or rather you’re just trying to save on time and labor, you may be able to let your zinnias reseed themselves. Keep in mind that oftentimes when plants reseed, the seedlings will not be spaced properly as they germinate.
You’ll need to thin out or transplant seedlings if you find a massive clump of zinnias growing together in the Spring. Also, zinnia seeds are held rather tightly in the seedhead. A great idea if you’re hoping for reseeding would be to crush the seedhead in your hand and gently scatter the seeds in the general area you’re wishing for your new plants to appear the following year.
Lightly raking them into the soil will also help. As always, having an excellent stand of plants through reseeding may not work out as you’d hoped. Sometimes seedlings will emerge too quickly in the Spring and be damaged by frosts.
Why won’t my zinnia seeds germinate?
Zinnias are warm-weather flowers. What’s that mean? They thrive in the heat of the Summer. Chances are if your zinnia seeds haven’t germinated, it’s probably because the soil hasn’t warmed enough to promote germination.
If you’re starting your seeds indoors, your seed tray may also be in an area that is too cool. Moisture is also key to germination. Let’s say it’s warm enough, but the soil has little to no moisture due to a lack of rainfall or hand-watering. Try watering your newly planted seeds if it’s been warm and dry. A third factor to look out for is seeding depth.
I have the best success when burying my seeds at least a ¼ inch deep. Another option is to broadcast the seeds onto the soil and then lightly rake them in to ensure good seed-to-soil contact.
Final Thoughts
After reading this article, I’m confident that you can collect and save your own zinnia seeds from year to year. These flowers are probably one of the most popular plants that gardeners save seeds from because it is so darn easy!
Zinnias are a beautiful staple summer flower for the backyard, so I encourage you to try your hand at saving zinnia seeds. And who knows, maybe you’ll create the next new zinnia variety in your very own yard!
