I read just before the buds begin to form, and I did but my endless summer is still pink. If you add too much it will burn the plant. I read 2 tablespoons dissolved in water at least one gallon and well watered.

I have a question to add...if you get the AS and water mixture on the leaves of the plant, will that hurt the plant?

The effect is not immediate (altering soil pH takes time), so you want to apply a dilute solution throughout the growing season, beginning as soon as the plant emerges from dormancy. For those varieties that bloom on old growth, you will need to continue this process into late summer and early fall, when the flower buds are set.

And you need to make sure your water is of appropriate pH as well. Irrigation water that is naturally alkaline will cancel whatever effects the aluminum sulfate may have.

It shouldn't hurt to get it on the foliage if you are using an appropriate dosage but it always best to try and keep any water off the foliage anyway to reduce the chance of disease. And the AS only has effect if it comes into contact with soils and roots, not foliage.