For decades, zinnias have been the flower of choice for spreading glorious colors throughout the garden as well as for cutting to bring indoors.
But it wasn’t always so. When the Spanish first saw zinnia species in Mexico, they thought the flower was so unattractive they named it mal de ojos, or “sickness of the eye!” Years of breeding have brought striking new colors, shapes, sizes, and growing habits to the humble zinnia.
When seeds of zinnias were introduced to Europe in the 18th century, the plants were not much to look at.
A breeding discovery led the way to the dwarf F1 hybrid Peter Pan series introduced from 1971 to1980. Seven separate colors won the AAS Winner award. Then the F1 hybrid Ruffles series (Scarlet, Cherry, and Yellow) was introduced as cut flowers. Although still available, these early hybrids have mostly been supplanted in the market by later introductions.
Compact zinnias are now “in”–perhaps in response to home gardeners’ smaller plots and the popularity of container gardening. Dwarf selections of Zinnia haageana were introduced decades ago but then a breeding breakthrough occurred. Two distinct species, Z. angustifolia and Z. elegans, were bred to create an interspecific cross.
Zinnia Profusion Series
In 1999 the Profusion series in Cherry and Orange won AAS Gold Medals, followed by White, Red, two double-flowered colors (Deep Salmon and Hot Cherry). They represented the best traits of both species: heat and humidity tolerant, disease-resistant, easy to maintain, pretty single flowers, and compact growth (12 to 18 inches tall). Then along came Profusion Red Yellow Bicolor which won the coveted AAS Gold Medal award in 2021. It has a stunning range of colors that start as golden yellow with a red center then morphs into soft beautiful shades of apricot, salmon and dusty rose.
2021 AAS Gold Medal Winner
Then along came Profusion Red Yellow Bicolor which won the coveted AAS Gold Medal award in 2021. It has a stunning range of colors that start as golden yellow with a red center then morphs into soft beautiful shades of apricot, salmon, and dusty rose.
One of the reasons for the popularity of the zinnia is its diversity.
- Zinnias have a variety of flower forms—single, semi-double, or double.
- Zinnias also come in an amazing array of colors. Most are solid, but some are bicolored with contrasting colors on each petal. You’ll find yellow, orange, cherry, pink, purple, scarlet, and white, as well as fashionable chartreuse—just about every color, in fact, but blue.
- Zinnias have growing habits to suit every need. Tall, 3- to 4-foot varieties are best for the middle or rear of a border or in a cutting garden. Dwarf plants grow 8 to 14 inches tall and do well in pots as well as at the front of a garden.
Growing From Seed is Easy
Starting Zinnia seeds indoor
- For earlier flowers, and in colder zones, you may want to give the plants a head start by sowing indoors.
- Sow the seeds indoors about 4 to 6 weeks before the average last frost date in your area. In frost-free areas, count back from the date when you’ll be planting tomatoes, impatiens, and other warm-weather annuals in the garden.
- Fill a shallow container or individual peat pots with a commercial seed-starting mix. Moisten the mix and let it drain.
- Sow the seeds and cover lightly with a layer of mix then spritz it with enough water to moisten slightly.
- Cover the flat with a sheet of plastic to keep the mix from drying out while the seeds are germinating. Set it in a bright location or under grow lights. Keep the growing medium at about 75º – 80º F (24º – 26 ºC) by placing it on a heat mat or warm surface.
- Seedlings should emerge in about a week. Remove the plastic cover and keep the mix evenly moist—not soggy—by watering the flat from the bottom.
- When the seedlings have at least two sets of true leaves, transplant into 2¼-inch or larger pots. Provide as much sunlight as possible so the plants don’t get leggy from stretching.
Sow seeds directly in the garden
- Wait to sow until all danger of frost has passed and the air and soil are warm. Amend the soil by digging in a 2-inch layer of compost before planting for better drainage and improved fertility.
- It’s easiest to sow the seeds in rows, but you can also sow them in groups. Cover smaller seeds (of Z. angustifolia, for instance) with about ¼ inch of soil, and larger seeds with ½ inch.
- Space seeds a little more closely than you’ll want the eventual plants.
- Keep the soil moist until the seeds germinate.
- When the seedlings have two pairs of leaves, thin them to the correct spacing. If you carefully pull out the unwanted seedlings, you can transplant them to other parts of the garden. Otherwise, simply snip them at ground level.
Caring for Zinnias
- Zinnias grow best in full sun, which means six or more hours of direct sun daily. In desert locales and zones 9 to 11, choose a site that gets some shade at midday and in the late afternoon.
- They prefer moist but well-draining soil—whether planted in the ground or in containers—so it’s important to prepare the planting bed by working in organic material, such as compost, especially if the soil is sandy, or heavy clay.
- One of the nicest aspects of zinnias is that a part of their maintenance requirements is cutting the blooms frequently to keep the plants compact and bushy and producing more flowers. Otherwise, planted in the right site in good soil, they are fairly carefree.
- Water regularly if it doesn’t rain. Even though zinnias love hot weather they do need moisture. Remember to check the soil in containers daily during hot summer weather and water if it is dry to a depth of 2 inches or more. In extremely hot, dry weather, you may need to water twice a day. Water at the base of the plants, rather than sprinkling the foliage.
- Zinnias aren’t heavy feeders but fertilize plantings at least twice during the growing season. Use a balanced granular or water-soluble fertilizer—for instance, one with 20-20-20 on the label—or mix a slow-release or organic fertilizer into the soil when you plant. Always follow label directions for amounts. Mix a timed-release or organic fertilizer into the soilless mix when you plant zinnias in containers or feed them once a month with a water-soluble fertilizer or diluted fish emulsion. Be sure to dilute to the strength recommended on the label for containers.
Tops as Cut Flowers
Zinnias are also wonderful grown for cutting. With good reason, zinnias have been referred to for years as “cut and come again” flowers: Cut one flower stem above a pair of leaves and, within days, two new stems with flower buds will have taken its place. All Zinnia elegans varieties make excellent cut flowers. Use the taller kinds in large arrangements; the shorter, dwarf ones in miniature designs. Properly handled, zinnias will last at least a week in a vase before they begin to look “tired.”
Zinnias in Containers
Choose a window box, wooden half-barrel, rectangular or round pot, or hanging basket—the bigger the better. Because zinnias are available in so many colors and sizes, they lend themselves to striking displays, whether alone or in combination with other annuals. Low-growing zinnias are best for containers.
Fill the container with a lightweight, soilless mix, rather than garden soil. Arrange plants until you have a pleasing design. Aim for a combination of taller plants in the center, medium and bushy plants around the middle, and a selection of trailing plants along the edge. Because zinnias, especially Zinnia elegans, can suffer without good air circulation, don’t crowd the plants. When you’re satisfied with the placement, remove the plants from their pots and set them in the mix at the same level they were growing originally.
Water the container well and keep the soil evenly moist through the season. Zinnias in containers perform best if you fertilize them at least monthly with a water-soluble fertilizer or save yourself the task and incorporate a controlled-release fertilizer in the mix before planting.
Pests and Diseases
Zinnias are often pest-free but can be impacted by two fungal diseases: powdery mildew and alternaria blight. Alternaria blight causes reddish-brown spots on both foliage and flowers and is a problem in the south more than in any other area. Powdery mildew can cause Z. elegans varieties to look terrible by late summer or early fall, covering their leaves with a light gray mold. To camouflage the lower foliage of affected varieties of zinnias, plant them with shorter annuals in front.
The best offense against fungal diseases is prevention: Don’t wet the leaves and do space the plants so they have good air circulation. Newer plants, especially the interspecific crosses of Z. elegans and Z. angustifolia, such as Profusion and Zahara, are very resistant to powdery mildew.
“This post is provided as an education/inspirational service of All-America Selections. Please credit and link to All-America Selections when using all or parts of this article.”