Dahlia hybrid 'Mystic Illusion' flaunts showy, star-shaped, yellow flowers that practically leap out from its dark foliage. Dahlias form tubers which can be stored for replanting in the spring. To dig and store tubers, allow frost to kill the top of the plant then cut back the stems and dig the tubers. Wash off any soil and allow the tubers to dry. Wrap dry tubers in newspapers or pack in peat moss.. Store in a cool (35 to 45 F), dark place. Deadheading encourages additional blooming.