The South Milwaukee gardens of Paul Berens and T.J. Kester were once a dull sea of grass accented with lots of red lava rock. But with ... I edged the pond with Lannon stone and planted some ...

Exposed to the oxygen present in air and sparked by lava, the sulfur burns readily, and its flames are bright blue. There’s so much sulfur, Grunewald says, that at times it flows down the rock ...