Days to Germination: 10-21 days
Hibiscus sabdariffa. Roselle plants love heat and sun, and they need a long season to produce flowers and calyxes. The farther north you live, the earlier you should start seeds indoors. In New England, for example, begin in late January or February. Nick or soak seeds before sowing. Provide warmth and even moisture. As the seedlings grow, transplant them into larger pots.
After all threat of frost has passed, slowly introduce the seedlings to the outdoors over a span of a week. Traansplant seedlings into the garden or into large containers only when the soil is reliably above 70°F. Water regularly and fertilize sparingly. Plants will begin flowering and forming calyzes in late summer or early fall, as they require shorter days to do so.