Answer: A pH of 6.8 would do for most plants, however, it is not acidic enough for azaleas or rhododendrons or blueberries.
Azaleas absolutely must have an acidic soil with a pH of 5.5 or preferably lower. Azaleas also need an organic and humusy soil that is evenly moist and yet well drained.
Also, I should mention that your zip code places you in zone 5A or the coldest part of zone 5. Depending on your microclimate it could be as cold as USDA winter hardiness zone 4. Most azaleas will not be winter hardy in your area.
I would also caution you to select roses that are rated winter hardy to zone 4, and preferably grown on their own roots rather than grafted, for best results.
Most plants will benefit from the addition of organic matter to the soil such as compost, old rotted autumn leaves, well aged stable manure/bedding and so on. This helps improve both clay based and sandy soils.
Using an organic mulch year round will also help to feed the soil on an ongoing basis as it breaks down over time.
With a pH that high you would not need to add lime to your soil. (Lime raises pH.)
Ideally you would fertilize based on soil test results, but in general you could use a general purpose or slow release granular form such as 10-10-10 or similar analysis. Read and follow the label directions for how much to use.
Your local Cornell cooperative extension should be able to help you with soil testing and interpreting the results, and may have suggestions for plants that do especially well in your local soil and growing conditions.
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