I live in NYC and would like to plant aome flowering shrubs/plants in front of my home. What are the best types for our climate? The soil very dark and rich. I am considering hydrangea .
Frost tolerance or hardiness is a major factor. According to the USDA Plant Hardiness Zones, your zip code is in Zone 6b. You can review the following article and plant list for some possibilities. Hydrangeas are really nice and on the list for your zone.
A local garden center will carry plants that are suitable for your area.