Dahlia pinnata Cav.
Bidens variabilis, Coreopsis crassifolia, Coreopsis georgina, Dahlia astrantiaeflora, Dahlia nana, Dahlia pinnata var. pinnata, Dahlia purpurea, Dahlia pusilla, Dahlia rosea, Dahlia royleana, Dahlia sambucifolia, Dahlia sphondyliifolia, Dahlia superflua, Dahlia variabilis, Georgia superflua, Georgia variabilis, Georgina astrantiaeflota, Georgina purpurea, Georgina rosea, Georgina variabilis
Color: Pink to deep purple
Bloom Time: July to October
Dahlia pinnata is a perennial herbaceous plant with rhizome and tuberous roots and an erect stem being branched only in the inflorescence. It grows up to 4 feet (1.2 m) tall, and it is the national flower of Mexico. Leaves are usually simple, with ovate, up to 4 inches (10 cm) long leaflets. The 2 to 8 flower heads have a diameter of up to 4 inches (10 cm) and appear on up to 6 inches (15 cm) long stems. The eight florets are ovate, pink to deep purple, and up to 2 inches (5 cm) long. The flowering period extends from July to October.
USDA hardiness zone 8a to 11b: from 10 °F (−12.2 °C) to 50 °F (+10 °C).
How to Grow and Care
Feed Dahlias about once a month with an organic fertilizer lower in nitrogen and higher in phosphorus and potassium, such as a 1-2-2 ratio. With enough compost, your Dahlias will do fine without fertilizer. Make sure your Dahlias get an inch of water per week. Keep track of rainfall so that the water is consistent.
Clip off spent blossoms to encourage more blooming. While optional, some gardeners remove many flower buds to focus the plant's energy on fewer, larger, and showier blooms with long stems. The flower buds come in clusters of three. If desired, remove the two side buds, allow the middle one to grow, and keep pinching off any more side buds that form along the end of the stem.
For a more natural look, pinch back Dahlia plants when small to encourage branching. Dahlias can be divided in fall or spring. Dig up the tubers and use a sharp knife to cut them into sections, ensuring each section has at least one eye. Allow tubers to dry overnight before replanting.
If Dahlias are hardy in your zone, simply cut them back after the first heavy frost and apply an extra layer of mulch to protect them from the cold. Remove the extra mulch in spring. In colder climates, dig up and store the tubers in a basement or garage, then divide and replant them in the spring.
See more at How to Grow and Care for Dahlia.
This species is native to Mexico.
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