Although purple coneflower, more commonly known as echinacea, is a popular treatment for the common cold, the plant is also a welcome addition to the home landscape. Purple coneflower is an especially good choice if you're attempting to attract wildlife to your garden, as the purple daisy-like petals will attract honeybees and butterflies, and birds will enjoy the seeds in the large cones after the plant is finished blooming in autumn.
Fill a celled planting container with commercial potting mixture. Set the container in a tray with about an inch of water and leave the container in the water until the potting mixture is damp clear through, but not soggy.
Plant two or three purple coneflower seeds in each cell. Although each cells will accommodate only one plant, it's best to plant extra seeds per cell in case some seeds don't germinate. Cover the seeds with a dusting of potting mix, no more than 1/8 inch.
Place the container in moderate light where the room temperature will be maintained between 65 and 70 degrees Fahrenheit. Cover the cell tray with clear plastic wrap to keep moisture in. Mist the potting soil regularly with warm water. The soil should be damp but never soggy, as too much moisture will rot the seeds. The coneflower seeds should germinate in 10 to 21 days.
Move the container into bright sunlight as soon as the purple coneflower seeds germinate. If your windows don't provide bright sunlight, place the seedlings under a grow light. Keep the soil just barely moist.
Pinch extra seedlings, leaving only one seedling per cell.
Feed the purple coneflower seedlings three to four weeks after the seeds germinate. Use a water-soluble fertilizer for houseplants, diluted to half of the mixture recommended on the label.
Prepare the seedlings for transplant outdoors--about a month after planting and after all danger of frost has passed--by hardening off the seedlings for approximately two weeks. Move the seedlings outdoors to a shady, protected place for the first two to three days. After that, the seedlings can be exposed to sunlight for 1 to 2 hours each day. Gradually increase their time outdoors until the seedlings are in sunlight for the entire day.
Prepare a sunny, well-drained spot for the seedlings. Use a tiller or garden fork to cultivate the soil to a depth of 6 to 8 inches. Work in 3 to 4 inches of compost or manure along with 1 pound of time-release granular fertilizer for every 50 square feet of planting area.
Use a trowel to dig a hole for each seedling. The hole should be no larger than the seedling's root system. Plant the seedling in the hole and tamp the soil gently around the roots.
Keep the soil moist until the plants are established and you see healthy new growth. After that time, purple coneflower is drought tolerant and should be irrigated only during hot, dry weather.