Q Can I help my healthy mimosa to flower? MRS S DRAPER, SHROPSHIRE A Mimosa (Acacia dealbata) is a fast-growing tree that’s best suited to milder areas. It flowers in early spring (usually February and March) from buds produced the previous summer. The buds remain on the tree throughout autumn and winter and if the winter is cold or the plant’s in a cold spot, the buds might be damaged and not open at all. If it’s still small, try moving it against a sunny wall to protect the plant from a cold snap.