On one of the hydrangea plants the flower is blooming as expected whereas with the other plant only some of the buds are blooming or not blooming at the same time to give it a nice pretty look. I have attached both pictures. What is wrong with the one that is not blooming simultaneously?
Hello: I have lots of hydrangea in my gardens and this issue was fascinating to me. The bottom photo is absolutely a lacecap flower, not a mophead, so I did some research and found this on ask.extension.org
Hydrangeas are usually propagated by cuttings so the only way they would change from mophead would be via mutation and it would be unusual for several bushes to change at the same time and all of the bushes to completely change. If you had a grafted plant that would be more likely to revert if the top were killed by cold/disease etc. then the understock could be lacecap. Soil pH and fertility shouldn't affect bloom formation but without seeing the blooms it wouldn't hurt to have a soil test done and see how you can improve the health of your plants.
These are two different varieties of Hydrangea - they're both H. macrophylla, but the second picture shows a lacecap variety, whereas the first shows a 'mophead' type. Lacecaps flower exactly as shown in your picture, and don't develop the full head of open flowers you see in the first picture. Guidance and images on types of hydrangea here http://www.hydrangeashydrangeas.com/identify.html
J. Storage, you need to check the pH. Pink means more alkaline. Blues and purples mean the correct amount of acidity this plant loves. If pH is off then you will see deficiencies in chemicals/nutrients the plant needs for normal functions. Looks like the pH is way off by the color of the flowers...pretty amazing huh! Not to mention the leaves are showing deficiency. If the pH is off some chemicals will not be available to the plant loving a different pH. Check the pH and tell us what you've used for fertilizer. Too high nitrogen coming in from possibly your lawn fertilizing could be a culprit in low reproductive growth. The leaves are saying they are unable to take up proper chemistry. When plants gets stressed? Plants will put all of their energy into reproductive growth. Lots of flowers, sickly vegetative growth. changing pink to blue Don't take the entire article as gospel okay?
And those flowers are not on the same shrub as Bamboo indicated. Those are two different hydrangeas both needing a more acidic soil. No way could they be from the same shrub, yes??