Purple coneflowers are quintessential prairie plants. They are hardy, drought-tolerant, long-blooming, and are being cultivated in an ever-widening range of colors. It's hard to find a garden without at least one variety. They are a variety of echinacea, a native North American genus with about 10 species.
Not all make great garden plants, but purple coneflowers, or Echinacea purpurea, are by far the most popular coneflower. It has a more fibrous root system, rather than the long tap root and woody crown found in other wilder species, and is more adaptable to garden conditions and more forgiving of dividing and transplanting.
The common name "coneflower" refers to the way the petals angle backward, away from the center, forming a cone.
Features of the Purple Coneflower
Coneflower's daisy-like flower is actually made up of several small flowers. The petals are sterile and are there to lure insects toward the many fertile flowers in the central disk or cone. These flowers are rich in nectar and very popular with both bees and butterflies.
Flowers used to only be a shade of purple or lavender, with a dark center cone, but with all the hybridization that has taken place, petal colors now include white, green yellow, orange and deep reds.
Growing Purple Coneflowers
Most coneflowers will grow well just about anywhere and are labeled USDA Hardiness Zones 3 - 9. You may want to give them a little winter protection their first year, but once established, they are rugged and hardy.
To get the most blooms and the sturdiest plants, plant purple coneflowers in a spot that gets at least five hours of full sun a day. They will tolerate partial shade, but plants may flop or strain to reach the sun.
Coneflowers start blooming in early to mid-summer and repeat bloom through frost. They may take a break after their initial bloom period, but they will quickly set more flower buds.
Most coneflowers grown in gardens prefer a neutral soil pH of about 6.5 to 7.0. Although they thrive best in a soil high in organic matter, too much supplemental fertilizer can cause them to become leggy. The new hybrids need more TLC than the species.
Growing Purple Coneflowers from Seed
Coneflower hybrids tend to be sterile, but the species are relatively easy to grow from seed. If you'd like to save the seed, wait until the cone has fully dried. It will be darker in color and stiff to the touch. The seeds are attached to the sharp spines. You don't need to separate them, before storing or planting. You could plant the whole cone if you like, although you'll want to divide the many seedlings you'll wind up with.
Different varieties of coneflower will cross-pollinate. If you grow multiple varieties and collect the seed yourself, you may well wind up with some interesting crosses.
The seeds germinate best with some cold stratification. The easiest route would be to sow them outdoors in the fall, either in the ground or winter sown in pots. If you are going to start seed indoors, simulate the chilling period by soaking the seeds in water and then placing the slightly damp seed in a sealed container in the refrigerator for 8 to 10 weeks. Then take them out and plant as you normally would. They should germinate within 10 to 14 days.
Planting Purple Coneflowers
If you don't want to start your own seeds, there are plenty of varieties available for purchase as plants, especially through mail order. Plants can also be divided or grown from stem cuttings.
Coneflowers can be planted in either spring or fall. It is recommended you plant the new cultivars in the spring, to give them time to become established.
Be sure to allow for good air circulation to prevent fungal diseases.
Caring for Your Coneflower Plants
Coneflowers are often listed as drought tolerant, but they will do much better with regular water.
You can leave the plants standing through winter, to feed the birds. Shearing them back in the spring will result in bushier plants that bloom longer into the season.
Deadheading is the primary maintenance required with coneflowers. They are prolific bloomers and keeping them deadheaded (removing the dead flowers from living plants) will keep them in bloom all summer. Luckily each flower remains in bloom for several weeks.
Flowers start blooming from the top of the stem. As the initial flower fades, more side shoots and buds will form along the stem. Keep the plants deadheaded and you'll keep getting more flowers.
The newer cultivars seem to do best if you allow them to grow and flower without much deadheading or pruning the first year. Do not cut them back in the spring until new growth appears.
Pests and Problems of Coneflowers
For the most part, coneflowers have very few problems. As long as the plants are given plenty of room for good air circulation, they should not be bothered by fungal diseases. If you should see mildew or spots on the leaves, simply cut them back and let them fill back in.
Keep an eye out for aster yellows, a systemic plant disease that causes growth deformities in the flowers. It can affect hundreds of different flowers, not just those in the aster family. There is no known cure and it is spread by a leafhopper, so affected plants should be removed and destroyed as soon as possible, to protect other nearby plants.
Garden Design Tips for Coneflowers
Coneflowers tend to spread rapidly, forming large, wonderful swathes. They combine especially well with other native prairie type plants such as ornamental grasses, yarrow (Achillea), butterfly weed (Asclepias) and Joe Pye Weed (Eupatorium), but probably the best combination is with Black-eyed Susans (Rudbeckia). Both tend to bloom throughout the summer, creating an easy-care carpet of blooms.
Since coneflowers are so hardy, they are also good choices for containers. You will probably need to divide them at least annually, or they will start to die out in their centers.