You are not just restricted to Yeouiseo-ro, but also the Hangang River Park is a must see while visiting the island. The date of the Yeouido Spring Flower Festival changes every year, as it is totally dependent on the blooming of the flowers. The best predictions for when the blossoms will be at their best are found on Korean news and weather reports, so be sure to check TV broadcasts and online news postings as April approaches.
This is my very first Cherry Blossom experience and I totally fall for it. I'm going to go for the Japan's one for sure and the picnic is a must! I can't wait for the Sakura petals blowing in the wind while sitting under the cherry trees - like a dream!