A tender plant, an unexpected spring frost can damage or kill the dahlia if it is planted too early. Plant dahlias after all danger of frost in the area has passed.
Dahlias grow from a bulblike tuberous root system. The plant can also be started from seeds sowed directly into the flower bed each spring after the last frost. Dahlias can be started indoors in pots six to eight weeks prior to the last expected frost in the area to give the plants a head start and gain earlier blossoms in the garden.
Dahlias thrive in full sunlight but can tolerate a moderate amount of shade but blossom production may be reduced. A heavy feeder, the plant benefits from having a general purpose fertiliser worked into the soil two weeks prior to planting the dahlias in the spring. Choose a fertiliser with low nitrogen so the plant does not produce an abundance of foliage with few blossoms.
Harsh winter time weather will kill the dahlia tubers. Consider lifting the tubers in the autumn after the first hard frost for winter storage. Properly stored dahlia tubers can be replanted the following spring after all danger for frost has passed. Autumn is also the ideal time to divide dahlia tubers in preparation for springtime planting.