Are Zinnia Flowers Annuals or Perennials? Do They Reseed Themselves?
Thinking of adding some zinnias to your garden but aren't sure if you'll need to replant them every year? Many gardeners ask this basic question, as it can cause additional work each growing season. In this article, gardening and flower expert Taylor Sievers examines the zinnia flower, and whether it's an annual or perennial.
Close your eyes and think about the perfect garden flower. I’m sure a few key characteristics come to your mind when you think of this perfect plant. I’ve got a plant in mind, so let’s roll through a few of the most desirable characteristics we could expect from this garden plant here:
Easy to grow? Check. Heat and drought tolerant? Check. Big, beautiful, cheerful blooms? Check. Long bloom time? Check. Pollinator-friendly? Check, check, and check! Have you guessed what flower I’m thinking of yet? Drumroll, please… It’s the zinnia flower! These plants from the Asteraceae family (along with asters and sunflowers) have been a garden staple for many years.
Let’s say you’ve decided to plant some of these blooms because you want everlasting color in your garden. You want that patch in the backyard to be gorgeous for as long as possible! But now that you’ve got your gardening cap on, you may be thinking… Will my zinnias come back year after year, or will they only bloom for one year?
Are Zinnias Annuals or Perennials?
It depends on the species we are talking about, but regardless, zinnias are usually treated as annuals in the gardening world. There are a few perennial species that we’ll talk about below, but these species are typically not sold in plant nurseries or traditional seed companies, and therefore are mostly found growing in the wild.
Annual vs. Perennial
So, what exactly is the difference between an annual and a perennial?
Annual plants are those that complete their life cycle in one year. This means that the plant will sprout, grow, flower, and set seed usually within the Spring to Fall timeframe (depending on the plant and where you live).
Perennial plants are those that complete their life cycle over many years. Some are short-lived, while others are long-lived. Most of the time these plants are slow-growing and may even have woody growth (though not always).
Their aboveground growth (the stems and foliage) may die back during winter, but their belowground growth (roots, tubers, bulbs, or rhizomes) are still alive, and they act as storage organs for the plant. They store all the energy for the following Spring when the plants will break dormancy and begin growing topgrowth again.
Once established (which may take a few years), some perennial plants will continue to flower every year, and they may even flower within the first year of planting, but they’ll become larger and more vigorous as they age. Usually, there are early signs your zinnias won’t make it past a year, but many do and last quite a long time.
What Does It Mean to “Treat” a Plant as an Annual?
Sometimes, as creative and adventurous gardeners that like to push the limits, we may “treat” a fast-growing perennial flowering plant like an annual flowering plant. This means that instead of allowing the plant to live on into year two and beyond, we either discard it or at least clear the space for other plants in the future. Sometimes we do this because flowering takes so much energy out of the plant that it will take a few years to recover.
A great example of this is in tulip flower production by commercial cut flower growers. Tulips are perennial in nature. Every year, the foliage emerges from a bulb, and then a beautiful flower is produced. We can let the foliage die back naturally in hopes that a new flower will emerge the following year, and many home gardeners do this.
In commercial cut flower production, the grower is harvesting the flower stems so that they’re as long as possible for the end-user (usually, the florist), and this harvesting process takes away leaves from the plant. As we know from high school biology, leaves are responsible for photosynthesizing, and thus responsible for producing energy for the plant.
The following year after the tulip flower harvest, foliage may emerge from the tulip bulb, but you won’t see flowers for a year or two. The plant needs to regain energy in order to bloom once more because making such beautiful flowers consumes a lot of energy.
So, cut flower growers will often “treat” tulips like an annual. Every year they purchase new bulbs rather than worrying about whether their tulips will bloom the following year or not.
Zinnias are such easy-to-grow-from-seed plants that many gardeners will choose to collect zinnia seeds from their own plants or purchase new seeds. Also, in some cases, zinnias may reseed themselves in the garden, too.
Another reason a gardener might treat a perennial plant as an annual is that the plant may not survive the winter in that gardener’s hardiness zone. Zinnias are mostly native to the southern United States and Mexico, so in growing zones that are north of these areas, a perennial zinnia may not survive the Winter. Therefore, zinnias would need to be seeded again in the Spring, unless the gardener plans to take the plants in for the Winter (which may or may not be successful anyway).
Popular Zinnia Species and Varieties
Below are some popular varieties within each different species of zinnia. In total, there are 17 species of flowers in the Zinnia genus. This makes for a wide variety of different flower types that can suit almost any garden.
The species of zinnias that are considered annuals are most popular for the home garden and landscape. Annual zinnias are mostly used alongside a vegetable garden to attract pollinators, as a cut flower, or at the edge of a landscape bed to provide groundcover and color.
By far, this is the most popular zinnia species. If you’ve seen a zinnia before, it was most likely a variety of the species Z. elegans. This species is an annual that produces 1 to 3-foot tall plants with large blooms.
- ‘Benary’s Giant’ Series – This is the most widely grown variety series with prolific 4 to 5 inch blooms that are mostly mildew resistant. This series features 13 different colors.
- ‘Uproar Rose’ – This variety has stunning, large, rose-colored blooms and the plant is very well-branching.
- ‘Queen’ Series – This variety series has been all the rage in the cut flower world in recent years. The colors come in antique shades of rose, orange, and blush that fade gently into a lime green flower.
- ‘Zowie!’ – The blooms of this variety are unique with bicolor gold and magenta petals.
- ‘Oklahoma’ Series – These cute little blooms are much smaller in size (about 2 inches in diameter) than the large ‘Benary’s’ zinnias, but they pack a colorful punch nonetheless.
This species grows about 2 feet tall with flower blooms about 1 to 2 inches wide. Many of the flowers are two-toned.
- ‘Aztec Sunset’ – The colors of this variety range from red, orange, yellow, and even a two-toned orange and maroon.
- ‘Soleado’ – This variety has bright, cheerful colors of orange or yellow with a mahogany ring around the center.
Plants in this species are used mostly in borders, containers, and hanging baskets due to their low-growing nature, with dwarf varieties as low as 6 inches tall. Some varieties can be as tall as 3 feet, however.
- ‘Crystal’ Series – Carefree, single-petaled variety that comes in orange, white, and yellow. This series tops out at 10 inches.
- ‘Star’ Series – This series is vigorous with star-shaped flowers. The plants are known to be downy mildew resistant.
Zinnia peruviana or multiflora
Also known as “field zinnia”, this species is an annual that thrives in hot, dry climates. Because it easily reseeds, it is considered weedy in some areas. The plant will reach 1 to 3 feet in height with blooms of 1 to 3 inches across. The flowers are typically reddish-orange, though some can be goldish-yellow in color.
The species highlighted below are often found growing in the wild, with many of the species being native to the United States and Mexico. These species are usually not readily available to purchase from a plant nursery, but in some instances, the seed may be available for sale from native plant seed companies or you can collect seed yourself. Make sure to follow state laws in regards to collecting seeds or propagating wild species of plants.
This plant is a mounding perennial species (up to USDA Zone 4) known as “wild zinnia”, “Rocky Mountain zinnia”, or “golden eye”. Wild zinnias grow about 4 to 8 inches tall and spread by rhizomes, acting as a groundcover. The flowers are typically yellow, and it thrives on rugged terrain in warm, sunny areas. This plant can also be propagated by division or cuttings.
Also known as “desert zinnia” or “shrubby zinnia”, this species is a perennial (up to USDA Zone 6) with a woody base and herbaceous stems that become woody as the plant ages. Desert zinnia is low-growing and has silvery-green leaves and stems. It is found in prairies, plains, savannas, and meadows at high elevations and will go dormant during a drought. The petals are creamy-white with bright yellow centers (disk flowers).
Also known as “shortray zinnia”, this species has 5 to 8 distinctly stubby petals or no petals at all. Shortray zinnia will live as a perennial up to USDA Zone 8. It is considered a sub-shrub, or rather, a low-growing perennial with a woody base.
First off, if you haven’t already, I encourage you to try your hand at growing zinnias in your garden. You will likely be thrilled at the result! More importantly, though, I hope you’ve at least gleaned some knowledge on the difference between annuals and perennials, and how we, as gardeners, can push the limits to achieve variety and beauty in our gardens.
Whichever species or variety of zinnia you choose to grow, one thing is fairly consistent: the blooms pack a colorful punch to any landscape (well, except maybe the shortray zinnia) and each bloom is pollinator heaven, too!