Sow directly in the garden after the last spring frost when night temperatures stay above 10 C, or start seeds indoors 4 weeks before last frost. Sow 1/2 inch deep in fertile, well-drained soil, spacing seeds 3-4 inches apart. Thin seedlings to 10-12 inches apart for healthy growth. Water regularly to maintain soil moisture keeping water off the leaves to prevent disease. Remove old flowers to promote reblooming.