The main part of Florida crosses three USDA hardiness zones: zones 8 to 10. The Florida Keys are in zone 11. That adds up to a wide differential among the lowest average temperatures that the zone system is based on. Gardeners in the different sections of Florida may have different choices when it come to flowers, and the flowers may look very different, but each one is just as spectacular as the next.
Hollyhock (Alcea rosea) is a biennial member of the mallow family producing leaves that grow from 1 to 2 inches long and about the same in width the first year and an abundance of yellow, red, pink, purple or white funnel-shaped flowers that grow from 2 to 4 inches across in the second. The plant then dies and a new one grows from the seeds the following year. The plant grows to a height of 6 to 8 feet. Plant hollyhocks in full sun in soil that is moist and well drained. The flower is hardy in North and Central Florida.
Frikart's aster (Aster x frikartii) grows about 2 to 3 feet tall and the same in width producing dark-green hairy leaves and an abundance of daisylike flowers that grow about 2 1/2 inches in diameter with lavender-blue petals and a yellow center. Plant Frikart's aster in full sun and a moist, well-drained soil. The flower is hardy in North and Central Florida.
Golden canna (Canna flaccida) grows up to 4 feet tall with thick, succulent leaves that reach up to 2 feet long and 6 inches wide. The bright yellow flowers measure about 3 inches across and grow in clusters at the ends of the branches. Plant golden canna in full sun or partial shade in moist, organically rich soil. The flower is hardy throughout Florida including the Florida Keys.
Crown vetch (Coronilla varia) is a member of the bean family that spreads out far and wide. The flower can quickly take over a garden if it is not kept in check. The plant produces leaves that grow to about 1 foot long and tiny white, pink or purple flowers that grow in clusters from summer through fall. The flowers are followed by thin, 2- to 4-inch long seed pods. Plant crown vetch in full sun and a moist soil. The flower is hardy in North and Central Florida.
Turk’s cap (Malvaviscus penduliflorus) is also known as sleeping hibiscus and cardinal's hat and is a member of the mallow family. It grows up to 10 feet tall and blooms all year long. Its 8-inch green leaves are oval shaped, and the flowers are 2 inches long, red and tube shaped. Plant Turk’s cap in full sun and a moist to dry soil for the best results. The plant is hardy in Central and South Florida and the Florida Keys. In North Florida, it will die back to the ground in the winter and reappear in the spring.