to be in full bloom; to blossom in full glory; to be in fullness of bloom
桜が見事に咲き誇った。
The cherry blossoms bloomed in full glory.
庭のバラが今年も咲き誇っている。
The roses in the garden are in full bloom again this year.
初夏になると各地の薔薇園で花が一斉に咲き誇る。
When early summer comes, flowers burst into full bloom in rose gardens across the country.