Hydrangea Blooms

Question

My hydrangea blooms, but not fully. It has plenty of heads, but they only partially flower. It is in a pot. This is the second year this has occurred.

Answer 1

It is likely lacking a good phosphorus/nitrogen balance in the soil. Too much nitrogen or too little phosphorus will cause it to fail to bloom. This article will have some other suggestions as well:
https://www.gardeningknowhow.com/ornamental/shrubs/hydrangea/hydrangea-not-blooming.htm