Zinnias can be direct seeded or transplanted. If transplanting, sow seeds in containers ¼” deep in late April, and transplant outside after 5/21 with 9-12” spacing. Alternatively, direct sow outside after 5/21, ¼” deep, about 2” apart. After first true leaves appear, thin plants to 9-12” spacing.
For best cut flowers, harvest before flowers are completely open. Deadheading will increase number of blooms.
Wait for seed head to dry completely on the plant, it will be brown. Harvest seed heads into paper bag, dry further inside, then rub to release seeds.