I heard a story that 28 years ago, the last time Birchas Hachammah was recited, Rav Chaim Kanievsky went outside to say Birchas HaChama and saw a tree in blossom for the first time that season.
He had to decide which comes first, Birchas Ha’Ilanos or Birchas Ha’Chama. You might think that Birchas Ha’Illanos is more tadir because we say it each year, as opposed to Birchas Hachammah, which we only say once every 28 years. On the other hand, Birchas Ha’Chammah is confined to a very limited time-frame – the first three hours of the day – whereas Birchas Ha’Illanos may be said at any point during the month of Nissan.