Dahlia 'Mystery Day' is a hybrid perennial grown from tuberous roots. Dahlias in general are native to Mexico, where they are the national flower. The tubers have been used as food by the Aztecs, and the flowers have remained popular for decoration. All Dahlias offered today are hybrids, literally hundreds of them. They have been hybridized for centuries. ‘Mystery Day’ has dark green leaves and will reach a height of 2.5-3 feet (0.76-0.91 m) tall with an equal spread. Plants are very showy when in bloom. Dahlias are hardy in the landscape in USDA zones 8-11. In zones 3-7, the tubers need to be lifted in the fall. As container plants in the greenhouse, they make outstanding cut flower material. They are very easy to grow.
Blooming: In the greenhouse, plants in containers bloom from mid May until late fall. The 6-9 inch (15-22.5 cm) flowers are very showy.
Culture: Dahlia 'Mystery Day' needs full sun to light shade with rich moist soil. We use a soil mix consisting of 2 parts peat moss to 2 parts loam to 1 part coarse sand. Originally, the tubers were placed in 5 gallon containers with tuber planted to a depth of 3 inches. The plants are kept moist but not overly wet. During the growing season, we fertilize the plants on a monthly basis with a 15-30-15 fertilizer diluted to ˝ the strength recommended on the label. During the winter months we move the plants to the cool rooms where the nighttime temperatures run about 48°F (9°C). Water is restricted during this period. In the landscape, Dahlias should be planted in a sunny location. When I plant mine I start with a hole that is at least 12 inches (30 cm) deep by at least 18 inches (45 cm) wide. To the hole, I add bone meal and mix it thoroughly into the soil. Tubers are then planted at a depth of 3 inches from the top of the hole. I drive a stake beside the tubers to help support the plants. Water well. As new growth starts and the plant reaches the top of the hole, it is gradually filled the rest of the way up. I keep the soil moist to a depth of 12 inches (30 cm). If you have a fairly rich soil, fertilizer is not needed if you use bone when the tubers are planted. In the fall as plants are going dormant, I lift the tubers and let them air dry after being washed off. The tubers are placed in slightly moist peat moss for winter storage.
Propagation: Dahlia 'Mystery Day' is propagated by cuttings and division of large clumps of tubers.
Dahlia 'Mystery Day' was featured as Plant of the Week June 22-28, 2007.
Guide to Past Plants-of-the-Week:
Cal's Plant of the Week was provided as a service by the University of Oklahoma Department of Microbiology & Plant Biology and specifically the late Cal Lemke, who used to be OU's botany greenhouse grower and an avid gardener at home as well. If the above links don't work, then try the overview site. You may also like to look at the thumbnail index. ©1998-2012 All rights reserved.