breeding ground
fertile ground

This was a breeding ground for him and nothing more.

So why has it been such a successful breeding ground?

Suddenly she saw her life as a breeding ground, a community under a rock.

The creek is an important breeding ground for both salt and fresh water fish.

What better way to create a breeding ground for envy?

They also say the area is the primary breeding ground for the area's mosquitoes.

Standing water, as in a pond or lake, is the main breeding ground.

"The university has been a real breeding ground for many an American artist."

They are the breeding ground for the future of music.

That has made the region a natural breeding ground for Communists.