Apple cider vinegar can be diluted half-and-half with water for external application, and, when stronger measures are needed, it can be used full-strength.
1 Just the stone for a flagstone patio can cost $3 -$5 a square foot or more, depending on location and the type and quality of stone, or about $600 -$1,000 for an average patio up to 10'x20,' and $1,200 -$2,000 for a larger 20'x20' area.
Shopping for a flagstone patio: 1  If possible, get several estimates. Be somewhat wary of a flat per-square-foot price quoted over the telephone; there are so many factors that can affect the cost, a contractor typically needs to see the site before giving a firm quote.