How to Breed Your Own Line of Zinnias

*Originally posted July 3, 2021

Traditionally zinnias have been bred to be bright, bold and punchy with saturated colors. I totally get why - zinnias have such a wide range of colors, everything from orange to red to yellow to pink to white to green to fuchsia to purple, and with their colors they stand out in the landscape and garden.

I think that my dissatisfaction with these zinnias comes not from their inherent color and appearance - personally I love those punchy colors - but because I’ve come to associate them more with casual, powdery-mildew-y, weedy plantings and arrangements they’ve fallen in favor with me over the years, especially if they’re from a mix that has a huge variety of shapes and sizes and colors that makes them clash rather than create a harmonious planting (or flower arrangement)

I’ve been happier with the soft, muted, peachy tones of zinnias like the ‘Queen’ series, ‘Zinderella’ series and the ‘Oklahoma’ series given that they come in shades of salmon, ivory, dusty purple and peach. They are great for using in designs due to their color and form, blending more harmoniously compared to the brighter saturated colors that you usually see.

And occasionally there is a particularly magical specimen that pops up here or there that is of a perfectly light peach tone, an icy lilac, or a dusty rose - a beautiful treasure that we had enjoyed in its ethereal beauty but was lost after the growing season was done.

Until now I had never thought about trying to save the seed from these zinnias - we had let them reseed from previous years, but they usually reverted into the wild-type single brightly colored zinnias that you see in mixes that we were trying to avoid.

I’ve been following Erin Benzakein’s efforts at breeding zinnias at Floret Flower Farm for many years - zinnias that have softer, subtle colorations like pale lilac, peach, buff, gold, pale peach, ivory and antique rose that are easier to blend in as colors (the more muted tones are what we call “bridge” flowers that bridge between different colors like burgundies and blushes) which would make them invaluable to flower farmers and floral designers alike.

Recently, she’s been posting her zinnia breeding efforts, with multiple hoop houses and tunnels and bumblebee and bluebottle fly pollinators dedicated to growing seed to create beautiful, magical, precious zinnia seed lines that will change the way we look at zinnias as cut flower growers. And it’s really cool to see- you’ve never seen zinnias like these before. I’m particularly interested in what she refers to as her ‘Precious Metals’ zinnia line - pale peach, buff, pink, blush and lilac fully double flowers that achieve a slight coppery-blue, almost teal coloration to the petals as they age (thus the name).

And although we don’t have hoop houses or tunnels dedicated to entire lines of zinnias, we do have the ability to breed our zinnias on a smaller scale!

Breeding zinnias is far easier compared to breeding other varieties of plants. Take for example David Austin roses - although they are seemingly introducing new varieties all the time, the reality is they are probably growing thousands and thousands of seedlings out, waiting years to see if there are any seedlings that are worth pursuing. And then it takes more time to ensure that any seedlings of interest perform well and meet the standards of growing, and then several more years to produce enough plants to market and get to the consumer (incidentally, this is the reason why plant patents are important and why patented plants cost more - so we can continue to encourage those ongoing efforts at breeding and bringing new varieties of plants to market. It wouldn’t be profitable otherwise).

Zinnias are great flowers to breed because they mature very quickly - given their annual nature, they proceed from seed to mature flower in just a few months. As opposed to a plant like a lilac or a hydrangea or a daffodil that will take several years to grow from seed into a fully mature plant (before you even decide if it’s worth keeping or not!), you’ll know the same year if your breeding efforts have produced something that you’re satisfied with by its flower and form.

Zinnia Anatomy 101

The colorful petals are what are known as “ray flowers” (or florets) since they radiate out from the center of the flower while the little star-like yellow petals are known as “disc flowers” (or florets).

The zinnia will start blooming first from the outermost petals (the ray flowers) and then the disc flowers on the outer most periphery of the disc will bloom, with each successive ring of disc flowers blooming until it reaches the center of the disc.

The interesting thing is that both the ray flowers and disc flowers can actually produce seeds - the seeds will look different, but both can grow into full-fledged plants.

How to Pollinate Zinnias

Zinnias in nature are pollinated by creatures - bees, hoverflies, butterflies and moths in particular. This is great for the zinnias, but if you’re wanting to be a bit more precise you can take control of the pollination by becoming the pollinator yourself.

To pollinate a zinnia, you’ll need the following:

• An organza bag (to isolate the flower head and prevent other pollinators from getting in)

• A paintbrush or a Q-tip

Find a zinnia that has pleasing characteristics that you like - color, shape, form, growth habit etc. - and wait until the disc florets have opened into their star-like shapes.

Once the disc florets have opened, you’ll take your paintbrush or Q-tip and collect the yellow pollen from either the ray floret anthers (the small yellow thread-like anthers at the base of the ray florets) or the disc florets (since again, both the ray and disc florets will produce seeds).

In an interesting study by zinnia flower breeders, they found that the seeds from the ray florets are more likely to produce fully double blooms (i.e. big, fluffy, mounded zinnias). And even still, the presence of fully double blooms is problematic because they are far less likely to produce viable seed since the increased layers of petals means fewer ray florets (if any) which is why even the most double-form of zinnias (like the Oklahomas) will still have singles and semi-double blooms in the mix (which are needed to continue the production of seed).

Thus in short, if you want to produce more double blooms, only pollinate and harvest the ray florets. If you just want to continue the color and general form, then pollinate and harvest the ray florets and disc florets for seed.

If you want to ensure that your zinnia self-pollinates (to allow for the increased retention of the traits you’re desiring such as color and size) you can put an organza bag over the top of it to prevent pollination from insects and ensure that 100% of the seeds are pollinated by you.

Wait Until the Seed Ripens

It will take around 7-8 weeks from the time that the zinnia is pollinated until the seeds are fully mature and dry and ready to harvest (depending upon the conditions of the growing environment). The ray petals will fade and brown and then dry up, and then the seed heads will also dry out at the base of the flower.

Personally, we like to pick our seeds earlier - after the seeds are pollinated but before they are 100% brown and dry. This allows for us to ensure that we don’t lose seeds to the birds (there are plenty of other food sources for them) as well as preventing that weird circumstance where high humidity and precipitation can cause seeds to start sprouting before the flower head is fully dried out!

Save Your Seeds

The best conditions for seeds are cool and dark and with little to no humidity.

Once they are dried, I keep our zinnia seeds preserved in a foil pouch in the freezer - away from ice or any other potential sources of moisture.