Several years ago we bought an Endless Summer Hydrangea. We needed something for the east side of our house along the foundation. We were told that if you have alkaline soil the blooms will be pink
and if you have acidic soil the blooms will be blue.
The above pictures were from our hydrangea. From this year. And, I took the pictures on the same day, June 26th.
These were taken just last week:
Somehow, we have ended up with both pink and blue blooms on the same plant this year.
According to several sites that I have looked at, you can change the color of the hydrangea yourself by adjusting the pH of the soil. First, have your soil tested to see what the pH of your soil is. Go to the local extension service and they will give you a small bag and instructions on how to test your soil. Essentially, you get a bucket, take some samples of soil from several areas of the space you want tested, mix it together and then put a certain amount in the bag and send it to Iowa State University at the address provided on or with the bag. You will get a letter back with the results and then you can adjust accordingly. You should recheck the pH of your soil every 2 to 5 years.
According to this site, you can raise the pH of the soil by adding dolomitic lime several times a year and turn the blooms pink.
You want the pH to be 6.0 to 6.2, but if it goes above 6.4 the plant may suffer from an iron deficiency. If you add a fertilizer with high levels of phosphorous, that helps to prevent aluminum from being taken up into the plants system and turning the blooms blue.
If you want those blue blooms,
you want a pH of 5.2 to 5.5. Check to see what the pH of your water is, too. If the water is too hard, it will be difficult to turn the flowers blue. The article also mentions that concrete foundations and walkways can leach lime raising the pH in that area, but our blue blooms are closer to the foundation than the pink ones, so that may not always apply. In our area, the Iowa State Extension service recommends using aluminum sulphate to lower the pH of the soil.
Another thing you want to be aware of, hydrangeas are very, very thirsty. We found this out the first year we had it. We would water it one day and the next, or even that afternoon, it would be wilted. We got into the habit of filling a five gallon bucket of water and dumping it on the plant each day, especially when it was hot. And the plant isn’t even in the hot afternoon sun! We found the solution in a handy little device that a friend of ours told us about. The self-retracting hose reel.
I love this thing. Not only does it save on my back while trying to reel in 100 feet of hose, it ends up watering the hydrangea. Win-win.
The other thing about Endless Summer Hydrangea is that it blooms on both new and old wood. Ours dies back every fall. We leave the old leaves on to give a little shelter for the winter. In the spring, we pull the dead leaves off and there is usually some growth already starting in April. It grows pretty quickly and the flower heads are huge! Since we brought ours home, there are some other hydrangea varieites that have been developed. All are beautiful and all would look great in your garden.