Garden zinnias are tough, fast-growing summer annuals known for blooming in a vibrant rainbow of forms and colors except true blue. There’s even a pure-green cultivar, which is a horticultural rarity.
Zinnias made history as the first flower grown in space on the International Space Station (ISS). A bright orange zinnia bloomed on January 16, 2016, inside its veggie plant growth system. The zinnia test was a vital step for learning how to cultivate flowering, fruiting crops like tomatoes on long missions.