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.
The cost estimate includes: 1  Costs for local material / equipment delivery to and service provider transportation to and from the job site. 2  Costs to prepare the worksite for Flagstone Patio Installation, including costs to protect existing structure(s), finishes, materials and components.