10 to 15 days. Acacia flowers are open in the late spring and early summer season, the flowering period for the annual April and May, flowering time of 10 to 15 days, about the morning that will open. Sophora is also known as acacia flowers, broadly speaking, acacia flowers refer to the flowers and buds of the legume family, more open flowers are called acacia flowers, also known as acacia stamens, and the buds are called acacia rice.