Which one is correct:
1. A house surrounded by green.
2. A house surrounded by greenery.
Depending on the context, both might be correct.
"A house surrounded by green" might be correct in the context of a house set among green fields or forests [perhaps at some distance from the house], whereas "a house surrounded by greenery" is a house surrounded by bushes or trees, or anything else with green leaves. "Greenery" implies something cultivated for decoration.
I'm not a teacher of English, but I have spoken it for (almost) all of my life....
"My parents live in a small cottage in the countryside. It's surrounded by green and it's got a well-kept garden"
So both 'green' and 'greenery' are possible here but with a difference in meaning?
I can't imagine ever saying a house was surrounded by green.
Maybe if I was talking about a painting.