Zinnia California Giants Mixture Nice Garden Flower 1,200 SeedsCategory: Zinnia CollectionAnnual. Zinnia California Giant that produces HUGE flowers that can measure up to 5” in diameter. This is an annual flowering plant that establishes quickly, blooms within 6-8 weeks after sowing seeds and is a stunning addition to your garden. Like most zinnia, the California Giant variety will bloom in early May and grace your garden until first frost. With exciting Mixture of cherry, orange, pink, purple, scarlet, and yellow, this flowering plant will grow to a height of 3 - 4 feet, loves full sun and is very low maintenance, although they do need to be watered regularly.