You mentioned the pines, so is it actually being blocked from the sun? That would be my first thought. They need a lot of sunlight and if the blossoms are 'weak' looking, that may be the case. I have also never heard of the pH affecting an Echinacea (coneflower) like it will a hydrangea, though I guess if it is way out of the norm, that would be a possibility. My next step would be to go back to where you got it and ask them, especially if it is a garden center, since they specialize in plants. The site at the link (an article on Echinacea) also has the option to Ask A Gardener. It's free! Just click on the blog tab and scroll down to the Ask a Gardener banner.

Here is a link that might be useful: About Echinacea