Answer: You have a challenging site indeed! Don't worry, there is hope for your plantings. If you replaced the excavated soil with topsoil, it probably is pH adjusted already. Though most perennials prefer a pH close to neutral, the ones you've chosen may be somewhat acid-tolerant. I am a little concerned about the excavation you did and how it may affect your pine trees. If you had to cut a lot of roots out of the soil this might affect the health of the pine trees over time. That, or the trees will grow roots into the new soil very soon and within a few years, compete with your plantings for moisture and nutrients. Unfortunately, they are very competitive, but you sound like you're committed to keeping your flower beds going, so I'm sure your plants will get plenty of moisture and rich nutrients.
You can call your state agricultural extension office (ph# 860-486-2739) to obtain a soil sample kit that you can send in for testing for a small fee, or you can buy simple soil pH test kits at most garden centers. The nice part about having a lab test the soil is that they provide specific recommendations about how to correct any nutrient and pH imbalances. Annual applications of garden limestone may be in order to maintain you soil's pH level.
If you find you need to make a relatively quick pH adjustment, see if you can find a source of Agrand Brand liquid lime (here's one: http://www.oilshop.com/fertilizer/fertilizer.3.htm). I hope this helps!
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