Answer: Purple coneflower (Echinacea pupurea) is a hardy perennial; perennials are traditionally started in mid summer but you can certainly start them in the spring. As with all perennials, the timing is a bit less predictable than for annuals, however. Purple coneflower seeds usually germinate within a week or two at normal household temperatures, but if nothing happens after a month, you can try chilling them to between about 24 and -39?F for a few weeks and then try germinating them again.
It's always better in my experience to set transplants out on the small side or wait a week or two if needed to let them catch up rather than to set out overly large (and consequently stressed) plants, so I would estimate about a ten week time frame. The ultimate growth rate however will really depend on the growing conditions you can provide them. If you have optimum conditions and plenty of space then a twelve or fourteen week schedule might do.
Once they are in individual pots and the weather is moderating, you'll want to move them outdoors gradually so they can become acclimated or "hardened off". Sometimes this plant will bloom moderately the first year from seed, but not always. Most gardeners will plant their first year perennials in a nursery bed where they can be watched over and weeded and watered as needed until they reach a more garden-worthy size and display. Good luck with your flowers!
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