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5 Great Tips for Growing Dahlia Zinnias

Dahlia zinnias are round, multi-layered petal flowers that are about four and a half inches in diameter. You can find them in a wide variety of shades, including white, bright yellow, soft orange, blood orange, purple, and deep red, all with deeply saturated colors. They make gorgeous standalone flower beds as well as borders within a garden. 

Field of zinnias

These summer and fall-blooming flowers (and the bees and butterflies they attract!) make an eye-catching addition to any garden or home, so read on to learn how to take care of them!

About Dahlia Zinnias

Dahlia Zinnia

Dahlia zinnias grow to between 30 and 40 inches in height. Native to Mexico, these plants prefer dryer conditions in Southwestern gardens. They are also available as Giant Dahlia Zinnia, which averages a height of about 50 inches.

These plants have semi-double and double flowers, which means that there are two to three times more rows of petals than other types of flowers. With semi-double flowers, you can still see the center of the flower. 

Dahlia Versus Zinnia

While both dahlia and zinnia are in the sunflower group, and they have some physical similarities, they are actually completely different flower plants! Dahlias vary more widely in size, with some bigger, and some smaller, than the average zinnia. Dahlia flowers are bigger and flatter than zinnia, and zinnias have a wider array of colors. Dahlias also grow taller than zinnias do on average. 

They also prefer different zones. While dahlias are quite picky, thriving only in USDA Zones 8 to 10, zinnia are hardy and can grow in Zones 2 through 11. Both flowers are brightly colored and beautiful, and in overlapping growing zones, they can be placed side by side in the same bed for an especially mesmerizing effect. 

So, what is a dahlia zinnia? Surprisingly, it’s not some sort of cross between the plants! Dahlia zinnias are part of the zinnia group, and they got their name due to their resemblance of the flowers of dahlias, with their dome-shaped and multi-petaled blooms. Given their many differences in growing, it’s important to make this distinction. 

How To Grow

Dahlia Zinnia

Like all zinnia, dahlia zinnias are considered relatively low-maintenance. 

Ordering Seeds to Grow at Home

Dahlia zinnias are relatively easy to grow at home. You can order seeds online from True Leaf Market or pick up some packets of seeds at your local nursery. When choosing a packet size, keep in mind that there are an average of 3,400 seeds per ounce.


This plant can be grown both indoors and outdoors. If you plan on planting in a pot indoors, keep the soil at about 75 degrees Fahrenheit. Sow four to seven weeks prior to the last spring frost. Press the seeds into the soil and lightly cover the seeds with soil. After three to ten days, seedlings will emerge. 

If planting in your outdoor garden, wait until all frost has subsided. Plant seeds in one-fourth-inch furrows, with four to six seeds per foot. Keep the soil moist by covering the bed. The plants require moderate to low water and mature within sixty to seventy days. 

Creating Ideal Growing Conditions

Dahlia zinnias require full sun and dry to moderate soil. These plants grow fast and bloom throughout the season, and they are annual, which means that the plant dies in the frost and must be replanted the following year. 

Dahlia zinnias prefer rich, well-drained soil. Sandy soil, loamy soil, and clay soil are all fine for dahlia zinnias. Add fertilizer often but lightly, as this encourages growth and blooming. Use a balanced 10-10-10 fertilizer mix for best results, like this Hoss All-In-One Vegetable Fertilizer, which you can order online from Hoss



Pests common to dahlia zinnias include aphids spider mites, and white flies, particularly if the weather has been hot and dry. You can get rid of them using an insecticidal soap on the lower base of the plant, where insects feed. Hoss has a Spinosad Garden Insect Spray that should be effective. Be sure to apply in the late evening. Otherwise, you’ll prevent beneficial insects and hummingbirds, too!

Diseases common to dahlia zinnias include powdery mildew, alternaria leaf spot, bacterial leaf spot, cercospora leaf spot, and aster yellows. Watering during the evening, when the water is less likely to absorb quickly, and will therefore sit longer, is a likely cause. Water in the morning to prevent most diseases. Growing plants in shade is another likely cause of disease. At the end of the season, remove all plant debris to reduce the possibility of pathogens being spread if this year’s plants were afflicted. 

Creating Stunning Bouquets for Various Occasions

Dahlia zinnias can be used to make beautiful bouquets. They can survive in a vase for about a week, though this can be extended with flower preservatives. Their colorful array of blooms pair well with each other as well as many other plant varieties. 

For a summery pop of color for a friend of to brighten your own home, create a pink and orange dahlia zinnia bouquet. 

For a rustic wedding bouquet, pair white dahlia zinnias with white garden roses, anemones, astilbe, and eucalyptus. 

As summer draws to a close, add sunflowers to your bouquet of rust-colored and deep red dahlia zinnias for an atmospheric autumnal bouquet. 

You can make your own dahlia zinnia bouquets, but if some of the other varieties of flowers are missing from your garden, you may prefer to buy bouquets pre-made. In that case, head to your local flower shop for a consultation!

Start Growing Dahlia Zinnias Today

Now that you have learned where to buy the seeds, how to plant them, and how to care for your plants, be sure to check out my zinnia page to learn more about the similarities and differences between dahlia zinnias and the many other varieties of zinnia out there!