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growing zinnias from seed

Zinnias: They're Not Outta Your League

You've heard about the "hottie paradox": Nobody asks out the most gorgeous, successful, and talented people because of the misconception that popular people can have anyone they choose, and they're probably already taken. So in the end, these delightful people spend their weekends all alone.

As oversimplified as that may be, it's kind of like that with zinnias. Folks think that because the flowers are so exotic and intricate that they'd be a colossal pain to grow and maintain in the home garden, and that a lowly freshman gardener could never pull off such a coup.

The Ryan Reynolds look-alike from the Sales crew with the six-pack abs and Tesla is probably way more high-maintenance than our zinnia varieties. He's going to be whining about protein shakes and persnickety paleo diets while you're sitting on your porch sipping well, Zinfandel, of course, enjoying all your zinnia's beautiful textures, colors, and shades. If you provide zinnias with the right conditions, there's not much you need to do to keep them happy aside from weekly watering and the occasional lopping-off of dead flower heads.

Zinnia's history and ethnobotanical significance

The Zinnia genus belongs to the aster and daisy family (Asteraceae). Altogether, there are about 20 species in the genus, and only half are grown as garden ornamentals. By far the most popular is Zinnia elegans. Zinnias are New World plants, native to hot, arid climates in the American Southwest, Mexico, and South America.

"Uncle" Carl Linnaeus named the genus for anatomist and botanist Johann Gottfried Zinn (1727–1759) who lived fast and died young; Zinn was the first to map out the human eye fully, and was also well-known for his study of the orchid genus. If he'd had the same access to cutting-edge experimental medicine as, say, Deadpool, who knows what else he'd have accomplished?

We can't quite put our finger on it, but there's something strangely relevant about zinnia's common names, which include:

  • Youth-and-old-age: Ol' Gottie Zinn made all sorts of comparative studies in his career, but this one? Not so much. Bummer
  • Mal de Ojos, or Sickness of the Eye: Creepy, given Zinn's ocular obsessions. This is the name the Spaniards used when they brought it to Europe in 1753.
  • Common or garden zinnia: Boooring.
  • Elegant zinnia: That's better, thank you.

Native American cultures in the Southwest made dyes and paint pigment from zinnia plants. The Navajo included zinnia among their "sacred life medicines," and Pueblo tribes believed that zinnias symbolized wisdom. According to the non-profit cultural organization Native Languages of the Americas, the Pueblo people fed zinnias to their kids to help them grow up to be articulate and intelligent.

This is probably a good time to say that zinnias are pet and family safe. Sorry, it's going to take more than zinnia tea to keep your kids from acting like complete idiots, and your dog will still run through your screen door every time it sees a squirrel, but zinnias won't kill 'em, either.

Gardening with Zinnia elegans

There are two types of zinnia flower heads: Cactus and dahlia. The petals on the latter type curl downward from the edges and twist to form points at the ends. Broader, denser dahlia types have flatter, rounded-tip petals.

Look for single, double, and semi-double flowers, which can be as small as an inch and a half across in dwarf varieties or five inches in diameter, such as those on our State Fair zinnia mix. Native zinnias were single-layered, but French gardeners like their stuff puffy, and introduced the first multi-flowered varieties in the mid-1800s; these do look much like true dahlias.

Ease of cultivation and two hundred years of fandom have created zinnias in multiple colors and shades, with bi- and tri-colored flowers being all the rage. The only color you won't find in your zinnia garden is blue, though that doesn't apply to the beneficial insects they attract. Zinnias are among the top butterfly garden plants.

Zinnia leaves are medium-green and lance-shaped, growing in opposite pairs up the plant stems; leaf length is up to five inches. From the top-down, a zinnia plant in its growth phase resembles a scaled-up basil plant.

Quick Facts:

  • USDA Hardiness Zones: Annual, suitable for zones 2 through 11.
  • Sunlight Preferences: Full sun! Light afternoon shade is okay only to prevent fading in darker-colored flowers grown for show.
  • Moisture Requirements: Zinnias prefer about an inch of water each week, but can tolerate intermittent drought.
  • Soil Preferences: Well-drained soil high in organic matter; the ideal pH range is between 5.5 and 7.5.
  • Plant Height: Can grow between 6" and 48" tall.
  • Plant Width: 6" to 18" spread.
  • Growth Habit: Upright, branching.
  • Bloom Period: June through first fall frost with deadheading.
  • Days to Maturity: 60 to 90 days, depending on the variety; this might seem like forever, but zinnias are among the fastest-maturing ornamental flowering plants.  


Pinch young plants to cultivate fuller growth unless you're going for long-stemmed fresh cut flowers. If you decide to use mulch to maintain soil moisture and temperatures, be sure to keep it away from the root crowns; as with Mr. Reynold's character in that one movie, they die if they're buried.

Pests and diseases

Common zinnia is vulnerable to blight, crown rot, leaf spots, powdery mildew, and root fungus. Predatory bugs include aphids, caterpillars, Japanese beetles, thrips, and whiteflies. There's an upshot to the whitefly's love for zinnias: Many veggie gardeners plant zinnias around their truck gardens to draw the little stinkers away from their cash crops.

You'll avoid most diseases (and mildew is the biggest threat) if you water your zinnias at soil level, provide them with plenty of air circulation and purchase fresh zinnia seeds harvested from disease-resistant stock.

Growing zinnias from seed

Prepare your zinnia beds by digging in plenty of aged compost and manure. Some zinnia buffs will actually add a whole layer of "fresh," rich topsoil to their beds each spring, but it's not necessary as long as the soil drains well and has plenty of nutrients. Primitive native zinnias evolved to thrive in desert soils, and improved varieties will put up with a lot of neglect, but why settle for substandard bloom production?

  • Seed Treatment: None required.
  • When to Plant Outdoors: Sow after all chance of frost is in your rear-view mirror.
  • When to Plant Indoors: Start your zinnias indoors 4 to 6 weeks before your last frost. Don't jump the gun; larger zinnia root systems are more prone to transplanting failures. Use a heat mat set at 70 to 75°F and a fine mist spray or channel tray to keep the soil moist.
  • Seed Depth: Plant your zinnia seeds no more than 1/4" deep.
  • Seed Spacing: Spacing varies according to variety and size; 1/2 to 2/3 the plant's typical height is a good distance for maintaining air circulation. Err on the side of generosity.
  • Days to Germination: Zinnia seedlings should emerge 7 to 10 days.

Root shock's a problem with transplanted zinnias, so we recommend sowing them directly in your flower beds. Otherwise, use biodegradable peat pots, which you can soak, score, and plant along with your starts. Because of the plant's relatively fast maturing rate, you can plant zinnias in succession so that you have fresh blooms throughout the summer.

Harvesting zinnias for cut flowers

Zinnias are outstanding additions to vase arrangements and bouquets. Choose a variety known for its height, and take advantage of the long stems for dramatic centerpieces. Don't listen to people who complain that zinnias only last four or five days as cut flowers. The National Gardening Association recommends harvesting zinnias when they're fully open, and pollen has begun to form. Beyond that, their advice for gathering fresh flowers is the same as we typically offer:

  • Carry a bucket of water with you in which to place your zinnias immediately after harvesting.
  • Once indoors, re-cut the stems at an angle while holding them under running water or submerged in a container.
  • Add a cut-flower preservative to the vase water or, as the NGA suggests, a teaspoon each of bleach and sugar.

Sorry. Zinn didn't have the recipe for Deadpool's immortality serum, and neither do we. Try asking Wolverine for a transfusion or something.

Contact Seed Needs

Do you feel a little more confident about growing zinnias from seed? We have about a dozen mixed variety packs, plus at least six of our favorite single zinnia varieties. But all that might change since we only stock a season's supply of ornamental, herb, and vegetable seeds, and they might be gone if you wait too long before placing an order!

Did you miss the boat? Have any questions? Contact us, and we'll do whatever we can to help you out. Sometimes, when we do run out of stock, it's nice to know there's still a demand. If we can't source more seeds from our trusted suppliers right away, at least we can plan for a larger inventory next year. Seed Needs has been growing since we first started 13 years ago, and we're grateful that your support has made it all possible!
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