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Orange Cosmos are colorful fall beacons
By Norman Winter
Central Mississippi Research & Extension Center
As you drive around neighborhoods and see gardens, the old-fashioned cosmos stands out like a beacon. I am not talking about the pastel pink and burgundy ones but the brilliant orange and yellow Cosmos sulphureus. This drought-tolerant member of the aster family hails from Mexico and Central America and loves Mississippi, too.
These awesome double or semi-double orange and yellow flowers produce prolifically most of the growing season. They attract bees, butterflies and the passers-by who gaze at the blossoms. It is not uncommon to see the old-fashioned strains reach 6 to 7 feet by fall.
With a little planning next spring, you can be envied by people throughout the summer. Sow seeds or set out nursery grown transplants in late spring in a weed-free, loose, well-drained bed. Seeds germinate quickly and will be blooming in eight weeks. Thin seedlings or transplants to 12 to 36 inches depending on variety. Add a good layer of mulch around young plants to help retain moisture and reduce weeds.
Deadheading old flowers will pay dividends with this plant as it gives the impression of wanting to bloom itself to death. Water the plant deeply during long, dry periods and give a mid- to late-summer pick-me-up with a light application of a slow-release, 12-6-6 fertilizer. You also can plant a mid-summer crop in front of or around the current bloomer.
Although the Cosmos bipinnatus is considered the taller of the two species, it is the Cosmos sulphureus that is at the 6- or 7-foot level in September. If you are growing a tall variety, you will want to plant them to the back of the border.
Blue or violet flowers make the best companions. To make the flower border sizzle, grow with salvias like the Indigo Spires, Victoria Blue, the Mexican Bush sage and the new Angelmist angelonias.
Another good, tall flower border partner would be the purple ironweed you see growing along the roadside. I just recently saw these in the landscape at the Gardens of Callaway in Pine Mountain, Ga. If they can use them in the landscape, we can, too.
Blue Daze evolvulus, New Wonder scaevola and Biloxi Blue verbena -- all three Mississippi Medallion winners -- would make excellent lower level companions planted in front. Try also Homestead Purple verbena.
There are a lot more varieties of cosmos than most gardeners realize. Planting by seed gives an option on variety selection. Bright Lights, a taller form in orange and yellow, is highly recommended. Cosmic Orange, a 2000 All-America Selection winner, and its counterpart, Cosmic Yellow, are shorter selections. Sunny Red, an All-America Selection winner from 1988, and the yellow version, Sunny Gold, are excellent dwarf forms, but getting harder to find. The Lady Bird series is also dwarf.
When you think about fall, colors like orange and yellow are the first to come to mind. The Cosmos sulphureus is among the best at providing these warm colors. Add a pumpkin or two, a bale of hay and a scarecrow for an unbeatable decoration.