Ashikaga Flower Park (https://www.ashikaga.co.jp/english/index.html) is my favorite place in springtime. In my experience, the best period to visit is between the end of April and the beginning of May.
I took the pic attached last year, and I will try to update this year, of course!!
CNN was introducing the park as one of the dream destinations for 2014.
Have a great journey. 🙂