DOES YOUR YARD have a problem location? Take a leaf from Beth and Robert Cummings Neville, who have turned a bad site into a good garden. Their Milton home is on a slanting rocky lot 20 feet above a busy street corner. “This place was just shale dust and crab grass when we moved in,” says Beth with a laugh. “We could have fracked it and made natural gas out of it.” Instead they’ve embraced problems as opportunities. Little by little, since 1988, they have built small terraces to control erosion while colonizing each rocky outcropping with improved soil and suitable plantings.Milton couple transform their third of an acre into a series of themed outdoor spaces.