Planting Instructions for Hibiscus Flower Seeds Planters Flower Pots + Garden Planters Terrain Campania Series 1 Planter P 812 Travertine 42" x 36" Cascading Plants That Spill Over Pots, Beds, Walls & Borders Gardening Know How Nigella is one of those flowers that actually prefers the cool soil of early spring. In Zone 6b, I start sowing my nigella seeds in late winter and continue sowing through early