The U.S. Department of Agriculture climate zone 9 includes regions where the average minimum temperature ranges between 20 and 30 degrees Fahrenheit. These locations are ideal for certain types of plants such as flowering perennials that thrive in warmer climates. Because zone 9 does not experience the harsh, freezing temperatures some of the other climate zones experience, flowering perennials come back year after year rather than dying off each winter.
Conditions in Climate Zone 9
Because the temperature in this zone rarely falls below 20 degrees Fahrenheit, plants growing here do not need to be cold-hardy. Temperatures in this zone can get very high, however, and humidity levels may vary. Desert portions of zone 9, for example, may experience high heat and low humidity, while coastal areas may have higher humidity. USDA climate zone 9 is divided into two different subsections -- zone 9a and 9b. The areas included in zone 9a have an average extreme minimum temperature of between 20 and 25 degrees Fahrenheit, and zone 9b has an average extreme minimum temperature between 25 and 30 degrees. Though both of these zones may occasionally experience freezing temperatures, winters are generally mild.
Growing Flowering Perennials
Under the right conditions, flowering perennials can last for three years or longer. Because perennials will grow back in the same location year after year, it is important to select the right location. While the ideal conditions for light and soil may vary from one plant to another, perennials generally do best in well-drained soil and they should be watered steadily throughout the growing season. In USDA hardiness zone 9, the temperature generally does not drop low enough that these plants need to be dug up and stored indoors over the winter. To prepare your flowering perennials for the winter, spread a layer of mulch around the plant in the fall and prune the plants back near the end of the winter to make room for new growth in the spring.
Canna, or canna lily, is a genus of flowering perennials that produce large, showy blooms. These perennials are hardy in USDA zones 8 through 11 and are available in several different varieties. Canna "Centenaire de Rozain-Bourcharlat," or Indian shot, typically grows to a height around 3 feet and produces large pink flowers. Canna "Madame Paul Caseneuve" grows a little bit larger and is known for its elegant beauty and soft pink flowers. Canna "Sémaphore" plants are the tallest of these three species, growing to a height of 6 or 7 feet. These perennials produce yellow-orange flowers. Members of the Canna genus only grow in full sun, and because they cannot withstand cold temperatures, climate zone 9 is perfect for them.
While many species belonging to the genus Cosmos are annual, Chocolate cosmos (Cosmos atrosanguineus) is a perennial flowering plant particularly well suited to the conditions in USDA hardiness zone 9. These plants are known for their chocolate-like fragrance and dark flowers, which work well for cuttings. Chocolate cosmos plants grow best in full sun and can be used in gardens as a border plant or grown in containers for decoration. In zone 9, you can simply mulch these plants in the fall and wait for them to grow back the next spring.
Dahlia is a genus of flowering perennial plants, many of which thrive in USDA hardiness zones 9 through 11. These plants typically produce colorful blooms that vary in size and range in color from light pink to deep purple. Dahlia "Bashful" is a relatively short plant, growing only 1 to 3 feet high, so it should be placed near the front of a flower bed. Dahlia "Bed Head" grows up to 4 feet tall and produces salmon-colored flowers that have a tangled appearance. Dahlia "David Howard" is a fairly large plant that produces apricot-colored blooms that contrast nicely when planted with dark-colored companion plants. Most dahlias thrive in full sunlight and prefer moderately moist, well-drained soil.
Your Planting Articles
- U.S. Department of Agriculture: USDA Plant Hardiness Zone Map
- Fine Gardening: Canna 'Centenaire de Rozain-Bourcharlat'
- Fine Gardening: Cosmos atrosanguineus
- Home and Garden Ideas: All About USDA Hardiness Zone 9
- University of California, Davis, Extension: http://ucce.ucdavis.edu/files/datastore/268-54.pdf
- Purdue University Cooperative Extension Service: Growing Perennial Flowers
- Fine Gardening: Dahlia 'Bashful'
- Jupiterimages/Photos.com/Getty Images