Answer: I wonder if you're trying to grow Catharanthus, which is commonly called "vinca"? True vinca is very difficult to propagate from seed (I can find no references for how to germinate it). Catharanthus is grown in an annual in Ohio, but is perennial in zones 9 and 10. Start seeds 12-16 weeks prior to planting out to ensure bloom for most of the season. You can transplant seedlings to outdoor beds when temperatures remain above 40F. Seeds should germinate within 2 to 3 weeks if kept in darkness and soil remains around 70F. Enjoy!
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