Iwate's Takamatsu Park features on the list of Japan's Top 100 Cherry Blossom viewing spots, and it's a popular destination during the spring season. The park grounds are home to over 1000 sakura trees that line the Takamatsu-no-ike pond, and boats are available for rent so that visitors can enjoy the blooms from a unique vantage point.
The best time to catch the trees at their best is typically the late April period, and admission to the park is free of charge.
Feasibly, if you visit Takamatsu Park you could also fit in Kitakami Tenshochi Park into your visit - it's another of the prefecture's top cherry blossom spots and is around an hour's drive away.