It is an older one that usually makes very large 3 lobed flowers. It seems to be wilting and dying one small part at a time. I've asked at our nursery here and followed their suggestions about pulling mulch father away and cutting down on the watering. But it seems to keep wilting and dying one stem at a time.
I've attached 3 pictures which I've taken over time since the beginning of August. I'm hoping they show the progression of the problem.
Tuscola County Michigan hydrangeas
Hydrangeas prefer moist soil. Their large leaves and flower clusters require large amounts of water on a daily basis. Letting the roots stand in soggy soil can result in root rot. Adequate drainage should be provided so that the plant is not overly watered.
If a hydrangea does not have enough light, it can wilt and have pale, unhealthy foliage. Lack of sunlight can also reduce the number of blooms. Too much sunlight causes sunburn and results in the foliage drying out quickly. Bright, indirect sunlight for 6 hours each day is the hydrangea's preferred environment.
If the hydrangea is subjected to extreme heat, the foliage begins to wilt, and the flowers begin to lose their petals. A temperature between 65 and 75 degrees Fahrenheit is ideal, with temperatures that do not fall below 50 degrees Fahrenheit at night.Too much nitrogen can cause a lack of blooms. Nitrogen fertilizers will encourage vegetative growth of this plant, but excess nitrogen can actually inhibit blooms. Hydrangeas generally prefer slightly acidic soils in the pH range of 4.5-6.5, If you have not done so, I recommend you conduct a soil test to ascertain if any amendments are needed to successfully grow hydrangeas. You can obtain a self-mailer soil test kit from Michigan State University Extension here:
The amount of chemical fertilizer used per plant will vary with the size of the plant and it's root system. Over-fertilization can be much more detrimental than under-fertilization. "Fertilizer burn" can occur when too much fertilizer is applied, resulting in a drying out of the roots and damage or even death of the hydrangea. It is much, much better to err on the side of too little fertilizer than too much. If a liquid fertilizer is used, it should be applied every month. Do not apply fertilizer next to the trunk or stems emerging from the ground.
When you prune your hydrangeas can also impact whether or not they bloom. You did not specify if your plant is an Annabelle, which blooms on new wood each year, or a mophead, which blooms on old wood. Since you've had this plant for several years, I will assume you know what kind of hydrangea you have and when to prune it. If I am wrong, please write back and I can help with that.