Cacti Dahlias are vibrant flowers perfect for adding a bit of spunk to your garden! The narrow petals are layered upon each other creating a lovely, spiky round bloom. Cacti Dahlias come in a huge range of colours. Cacti Dahlias tubers take around eight weeks from planting to flowering. Plant your Cacti Dahlia tuber in a sunny spot into moist, humus rich, well drained soil. Water in well then keep moist during active growth.