1. Hydrangea: blooms in summer from June to July. Blue flowers will bloom when the soil is alkaline.
2. Blue Snowflake: A typical blue flower with elegant color and flowering period from May to October.
3. Cornflower: highly adaptable, sun-loving, cold-tolerant, heat-intolerant, with blue flowers.
4. Gentian flower: Most of the flowers are in clusters. The flowers are not purely blue, but blue-purple to be precise.
5. Morning glory: an annual twining herb with blue, pink, white or purple flowers.