Blooming from summer to late autumn, dahlias make fabulous cut flowers and provide drama in borders with flamboyant shapes and colours. But how do you distinguish between spent flower heads and the new blooms? What do you snip off? Pointed buds are the old flowers going to seed, while round heads are new blooms. Take a sharp pair of snips and deadhead your dahlia, cutting pointed buds back above a pair of leaves. This will keep your plant producing flowers for weeks.