No photos attached so hard to say if this is normal behavior or out of the ordinary. The blooms will only last a few weeks and fade to brown eventually so it may be completely normal. Deadhead them if they are ugly. Endless Summer is supposed to rebloom on new wood and a good haircut may encourage new growth and blooms.

The blooms are spent. If you don't like the look of spent blooms, get rid of them.

Spent blooms come in a few forms. Yours is actually preferable, because in other cases the blooms will get moldy, or otherwise rot off - or, the sun can scorch the blooms to the point where they just shrivel up to nothing.

And be patient with the plant "holding its color" *and* rebloom potential. Unless you are in a southern or maritime climate, it can take 3-5 years for an ES to become properly established in the soil, where it will be more capable of pumping nutrients to the flower heads, and working up enough energy to create a second round of blooms.

Below is link to a picture of a typical look for the ES blooms after they mature or dry out (leave them on for winter interest or cut the petiole that connects the bloom to the stem and use the bloom as mulch... if the shrub does not have any fungal diseases). Deadheading promotes new blooms in ES.

Hydrangea blooms usually stay the same way they look for several weeks (maybe a month tops) before they start a color change progression that ends in browned out blooms. Each hydrangea does it like that but the colors progression varies from one variety to another say from pink to pink with some green, etc. Sometimes the shade of color changes and becomes more vibrant or darker, etc.

Soil pH impact: I would expect the original bloom color that you saw when it was potted for sale (the deep purple) will change as the roots grow into the ground and adjust to the soil pH in your garden soil. By next year, the blooms could be a shade of pink, blue or maybe still purple-ish if your soil is like the one in the pot.

http://3.bp.blogspot.com/-OQe0XzMwDrw/TllhVP2OYuI/AAAAAAAAApw/zCDgWj9q8Qo/s1600/Hydrangea+endless+summer+13AUG11.JPG

Luis

That is about as long as you can expect a bloom to last in the heat of summer. A month is a good length of time for a bloom to last. They age to a tan/brown color and get crispy as the blooms are spent. You deadhead behind the flower to the next set of buds for a rebloom later in the summer and fall. There doesn't seem to be anything abnormally wrong with your hydrangea that I can tell without pictures. My Endless Summer blooms a light purple, ranging to a deeper purple, and then a light blue at times. It seems to bloom in the middle of the pink/blue spectrum in our soil. Neither really pink, or blue, but in between as varying shades of purple. As the blooms age they begin to take on a dusty rose/red hue, and then slowly turn to tan/brown. I think they are quite lovely as they age. =]

This is a bloom after about 3 weeks. It began a light purple. Another week or so and the tips start turning brown, and then the whole bloom turns tan/brown as it dries.

Also, exposure to a lot of sunlight, especially mid day and evening sun will reduce the bloom life and cause it to age and dry out faster. Your hydrangeas should have limited amount of sun during the hottest parts of the day, preferably only morning sun. I do have a few that get a couple of hours of evening sun and light shade the rest of the day and the blooms last quite a while on them. They just can't tolerate full mid day/evening sun. =]

Thank yall so much! I think yall have explained it perfectly. I think I figured out how to attach he photos just in case they prove to show any other problems or further explaination.

Before:

I am not sure if your hydrangea is endless summer. The leaves look to be thicker than ES.

The color change suggests that the bloom is getting old. The browning suggests that the sun and moisture are problems. Common with newly planted shrubs not used to being out in the open. When stressed by "transplant shock" from the nursery to your garden, the blooms are the first ones to go. Deadhead them if you do not like them. Rebloomers will respond by producing new blooms in several weeks or a month if conditions are ok. Make sure you have 3-4" of mulch so you do not loose moisture to evaporation in the summer. If the leaves brown out from the edges inwards then moisture issues start to get more serious.

could it be prezoia or bloomstruck?

Bloomstruck has red stems and petioles. Definitely not bloomstruck.