Cosmos is famous for growing tall, and many people love it that way, waving in the wind. However, if you'd prefer the plants lower, choose this strain. Tall or not so tall, cosmos is one of the finest colormakers in any wildflower meadow and a big favorite for roadside plantings since these large flowers make such a colorful show. It's also one of the best flowers for cutting. Heavy bloom begins in midsummer and plants and flowers constantly increase until killed by frost.
The Cosmos Craze: New rage for an old favorite. When it comes to annuals, probably no plant adds more color than cosmos. Your grandmother grew it, today states plant masses along roadsides, and everybody loves it. (Birds love it too, especially goldfinches.) But there's always been one big problem--it's tall, sometimes very tall--up to 6 or 7 feet.
In the right setting, say a wildflower meadow in late summer, nothing's more beautiful than a sea of these big ferny plants waving in the wind, loaded with big blooms in pink, white and maroon. But in gardens, most people prefer shorter flowers. So for awhile, some relegated the "tall" cosmos to the group that's usually called "old fashioned flowers"--beautiful, surely, but a bit tall and rangy for our more sophisticated flower borders today.
Enter the hybridizers. With all that color and such ease of care to work with, they have had a heyday with cosmos. Today, there are all sorts of variations on the originals, some with new-style flowers, and others with simply the classic blooms on shorter plants. All require full sun, and are among the simplest plants on the planet to grow from seed. By the way, even the seeds of cosmos are distinctive; they look like miniature pine needles.
The originals are wildflowers, of course, and are native to our own southwest and more commonly, Mexico. This tells you cosmos don't mind hot dry, conditions. In fact, some consider cosmos desert plants. But they're incredibly adaptable. And ever since some plant explorer gathered seeds from the rocky wilds of Mexico and transplanted them into "good garden soil," the world has known that they not only thrive, but enjoy our loamy, well-watered gardens. And if they're not fertilized too much, they rapidly develop into large branching plants with deep green fern-like leaves. If you have a dry season, cosmos plants don't care, and revert to their drought-tolerant roots. Best of all, no matter where they're growing, they cover themselves with more and more wide (up to 4") daisy-like blooms from midsummer on. Only a hard frost stops the cosmos parade. They're fantastic as a blooming screen, or a background for shorter plants. And the big bonus: a grand stand of this garden classic in late summer can provide months of long-stemmed cut flowers for a whole neighborhood.
The Originals. There are scores of native cosmos species, most all native to the Americas, but there are only two that have entered our gardens in a big way:
1. Cosmos bipinnatus, the big one. This is the granddaddy of them all. Hailing from Mexico, it's one of the few wildflowers that is so beautiful it was taken into gardens long ago just as it is in the wild. The old name for this garden classic is simply "Wild Cosmos", "Cosmos Sensation," or "Sensation Mix," since the seeds always produce plants blooming in pastel pink, white, and deep red or maroon, all with bright yellow centers. These are the tall, (to 6 or 7 ft.) graceful cosmos plants of your grandmother's garden.
2. Cosmos sulphureus, the other cosmos. This one's shorter, with more bushy plants and somewhat smaller yellow (to orange) semi-double flowers. It's often called "Sulphur Cosmos" or "Orange Cosmos," and an old variety with particularly glowing orange blooms is called "Bright Lights." The flowers of these often remind me of open-style marigolds on larger plants.
The New Cosmos. Today, the old standard "mixture" flowers of C. bipinnatus have been segregated, and the plants grow from only 3 to 5 feet. So if you particularly like the old pastel pinks, there's "Pinkie," for the pure white, "Purity," and for the old deep rose or maroon, "Radiance." Even though the plants are shorter, all the flowers are still big and beautiful with the familiar bright yellow centers. And this new group doesn't stop with the old basic colors. "Gloria" is a beauty in pink with red-flared centers. And "Daydream" gives you the old pastel pink, but with a darker center flare and darker pink veins all through the petals.
If 3-5 feet is still too tall for you, choose the "Short Cosmos Mix" which gives you all three of the old mixture colors at just 2 to 4 ft. And yes, the flowers are still full size.
Want more variety? Pick "Dazzler" and enjoy unique blunt-tipped daisies in true red, still with the dazzling yellow center, on plants to 5 ft. Then there's the most unusual of all, "Seashells," a big hit with cosmos lovers--its hot pink petals are curled upward at the edges, giving the blooms a frilly look.
And here's my favorite: "Picotee." It gives you full-size daisy blooms in white with the end of each petal looking as though it's been dipped into a rich red paint--and all that jazz is on plants never over 4 feet. This one, like all the others, creates spectacular color in the garden, and even more in a vase.
More! More! If you'd like to read more about growing cosmos, read what well-known garden writer Deb Lambert has to say: Click here. She's a good writer and a big cosmos lover.