I live halfway between Baltimore and D.C. Over the past 10 years I have tried unsuccessfully to grow hydrangeas of different kinds and I need more info on how to find the right site--my neighbor across the street has gorgeous, healthy hydrangeas. We have a black walnut tree in our backyard, and I think my first two attempts failed b/c I didn't site far away enough from the tree. Our front yard would seem like a better choice, but it's very sunny. This year, I purchased two very healthy potted plants on impulse at the grocery store that came with no species/genus names(pix attached), one with blue flowers and one with pink; so far have kept in pots but would really like to establish in the ground. Can you advise what to look for on a site, and how to amend soil?
It might not be the black walnut. Read through this page about walnut toxicity: http://extension.umd.edu/hgic/walnut-wilt-juglone-trees-and-shrubs If toxicity is the problem, you should plant in the front yard. Hydrangeas need sun to flower and can grow in full sun. However, before you do, review good planting techniques for planting shrubs, just in case they were planted too deeply or have some other issue: http://extension.umd.edu/sites/extension.umd.edu/files/_images/programs/hgic/Publications/HG24_Plant...
Keep in mind that these are acid-loving plants, so avoid lime. Hydrangeas react very quickly to dry soil. Keep them well watered for at least the first two years while they get their roots established. A