100-200 seed/gram. Sow directly where you want them to grow. Select a sunny site with well drained, organic soil. Sow in late May when the soil has warmed. Cool, damp soil causes seed to rot. Barely cover the seed with soil. Under ideal conditions, germination will occur within a few days. When the seedlings are 7.5 cm (3") tall, thin smaller varieties to 25 cm (10") apart and larger varieties to 35 cm (14") apart. Thinning enhances blooming and improves the overall sturdiness of mature plants. Zinnias make excellent cut flowers. Plant several varieties in successive sowings to provide a steady supply of cut flowers.