Probably not bedrock - clay! Soooo many choices though - just not things that can't take the summer heat and humidity or are really too fussy about drainage. Are you interested in veggies or flowers?

George we're in the same zone, but we get furnace heat sooner in the spring/summer and it stays longer than NYC. We get a lot of temperature swing from day to day and during the day in the fall and winter.

Thanks for the response. Mostly I have flower seeds to give to my sis. Realizing we are in the same zone is a big help (guess I could have checked the USDA map before I posted-- but always great to have it from those who know!)
I will look into the kinds of flowers that do OK in heat and don't mind the clay soil.
I talked to my sis the other day, and she described putting in a tree in the back that she needed to take a pick-axe to the ground to make a hole deep enough for the tree. It that impacted clay? She seemed to think it was a kind of sandstone. The plot thickens!

In Greensboro (which is 7B by the old maps), it's probably clay. I live ten minutes east of city limits and there's nothing but clay anywhere near me. I do a lot of amending and use a mattock to chop into the soil. One tip I got that has been a real winner for me is to make sure to use a sharp spade to penetrate the bottom of planting holes for better drainage and a place for the roots to work into the subsoil more easily. I've has less problems with rot since I started doing that.

She'll love it here!...and Greensboro is a beautiful town.

Hi George, your sis may want to come to the local seed swap Saturday the 30th... 2:00 at Panera Bread on Hwy 68. She can meet some local gardeners and we always have plenty to share. Tell her to not worry about bringing anything since she's new to the area. She can talk to the locals about the soil/weather, etc... and find out what does/doesn't do well here. We also have plant swaps in the spring and fall which is a great way to try some new things or old favs.