Zinnias: Garden Stalwarts That Need A Comeback

It’s been more than a decade since I’ve written about zinnias. And I think it’s about time to pay attention to this stalwart flower.

Like marigolds, impatiens and petunias, zinnias have become somewhat lost in our gardens as we seek the newer, better and more exotic colors and forms to fill our horticultural fancies. It’s a shame because zinnias come in so many forms and colors with uses in containers, hanging baskets, the cutting garden and the blooming border.

Zinnias are incredibly easy to grow because the seed is easy to handle and germinates fairly quickly. They can be started indoors or out. And once in bloom, many varieties will continue to flower, with a little care, for five months or more. Depending on the varieties you choose, they will grow from only a few inches tall to a few feet tall and they just adore the heat of the summer.

There are more than a dozen species of zinnias, which are in the daisy family, but only three species are usually grown in the garden. All three are annuals and bloom from early summer through the first frosts of autumn.

Zinnia elegans

, the common zinnia, is very familiar to gardeners. Varieties—tall, medium and dwarf—have been in the garden for decades and the flowers are available in just about every color except blue.

Z. angustifolia

is less known but is currently gaining in popularity. This plant has narrower foliage and smaller single flowers. The species has golden-orange flowers but the Crystal White variety has pure white blooms with yellow centers. Crystal White is also more compact than the species, which can spread to 2 feet.

Probably the least known zinnia is

Z. haageana,

or the Mexican zinnia. It has remarkable disease resistance; grows to 15 inches; and has small, bicolored flowers. It’s an excellent cut flower because of its long and sturdy stems.

Even after seeds of zinnias were sent back to Europe in the 18th century, the plants were not much to look at. It wasn’t until the 19th century that breeding gave zinnias a touch of class. The breeding was done in Germany, Holland and Italy where two strains—Mammoth and Striata—were developed, as well as the popular Pumila Mixed, which led to the “cut-and-come-again” types that are still available.

From the late 19th century through the late 20th century, zinnias were the flowering annuals of choice for spreading glorious colors throughout the garden, as well as for cutting to bring indoors. The plant is especially welcome during periods of drought as it’s native from parts of the world where water is often scarce.

But the zinnia was not always prized for its beauty. When the Spanish first saw zinnia species in Mexico, they thought the flower was so unattractive they named it “mal de ojos,” which roughly translates to “sickness of the eye.” Needless to say, things have changed and the flower’s colors, plant sizes and disease resistance have also come of age.

Zinnias didn’t become popular in this country until the 1920s when Bodger Seeds introduced the giant dahlia types. Shortly thereafter, the flat-flowered California Giant type was offered and for the first time a flower was sold in separate colors, which at the time was considered a new and important trend in American gardening.

Then, in the 1950s, State Fair, the first tetraploid zinnia—which has four sets of chromosomes rather than the usual two, resulting in larger flowers, more ray florets, stronger stems, vigorous growth and increased disease resistance—came from Ferry-Morse Seed Company. That type ushered in the reign of larger plants with stronger stems, more vigorous growth and better disease resistance.

F1 hybrids, considered to be the cream of the crop, were harder to come by, though, because of the difficulty in manipulating the reproductive parts of the plant, which had to be hand-pollinated to produce seed. Then, quite by accident, a grower at Burpee found a plant in the field that had a flower with no petals and all female reproductive parts. This plant led to the dwarf F1 hybrid Peter Pan, introduced in the 1970s, which is still a popular variety today.

The most recent zinnia introductions are a result of the interspecific crosses of

Z. angustifolia

and

Z. elegans

. These introductions represent the best of both species—heat and humidity tolerance, disease resistance, easy maintenance (no deadheading) of the 2- to 3-inch flowers and compact growth of 12 to 18 inches.

One of the reasons for the popularity of the zinnia is the diversity of its forms. Like dahlias and chrysanthemums, zinnias have a variety of flower forms and petals may be single, semi-double, double or cactus.

Single-flowered zinnias have just one row of petals and the center of the flower is exposed. Semi-double has numerous rows of petals, but the center is still exposed. Double-flowered zinnias, which have so many rows of petals that the center is hidden, have several shapes. And the edges of each petal on cactus-shaped flowers roll under and the petal twists and bends.

When it comes to size, the petals on dahlia-flowered zinnias are large and flat and usually semi-double, which means that the flowers have many rows of petals but the center can be seen. These are great to use as cut flowers.

Zinnias also have an amazing range of colors. In fact, flowers come in almost every shade but blue. Most are solid but some, in particular

Z. haageana

, are bicolored with a contrasting color at the tip of each petal. You’ll find yellow, orange, cherry, pink, purple, scarlet and white as well as one unique chartreuse variety called “Envy.”

Height is an important consideration when planning a garden and zinnias have growth habits to suit every need. The tall 3- to 4-foot varieties are best for the middle and rear of the garden or border and in a cutting garden. Dwarf plants grow 8 to 14 inches tall and do well in pots and in the front of the garden.

Z. angustifolia

plants reach 8 to 15 inches in height with an equal spread and they are excellent in the ground, in pots or hanging containers and as flowering ground covers.

Next week, how to grow your zinnias from seed, the varieties that are resistant to the dreaded powdery mildew and how to control it if it shows up. Keep growing.