Zinnia haageana. Planting Soleado zinnia seeds in the spring results in a jubilant display of single flowers with two-tone orange petals surrounding concentric circles of mahogany and yellow. The plants are tougher than other Zinnias and will stand up to nearly any weather conditions, blooming right into fall. Plant height to 45cm (18″). Direct sow after last frost, in April and May on the coast. Zinnias don’t transplant well, but you can try starting some indoors in peat or coir pots 6-8 weeks before planting out. Maintain a soil temperature of 21-26°C (70-80°F). Seeds should germinate in 5-24 days.