How to Build a Cornish Hedge

Mark out the lines of the hedge with string. A Cornish hedge is 5 feet high, and the width of the base must be at least the same as the height, so the enclosed area must be at least 5 feet wide. Prepare the ground by removing debris and loose material. Dig out all the grass; creating sods at least 6-inches thick. Remove any remaining topsoil and all tree roots throughout the entire base area of the hedge. Store the sods and the topsoil nearby; you will need them later.

Sort the stones by size, laying the largest ones about 3 feet from the edge of the hedgeline, and grading toward smaller stones further away. Dress any stones with unwanted protrusions, and use a sledgehammer to break any that are too large. The result is a collection of stones laid out in parallel lines in the order in which they will be needed. Keep small chips and wedge-shape stones in a convenient pile nearby.

Lay the "grounders," the largest stones that form the foundations of the hedge. Place them with the roughest surface facing downward into the soil, and the smoothest side facing outwards. Scrape out the ground, if necessary, to fit the stones snugly to the ground. Alternate the size of the grounders so short and tall ones alternate.

The tops of the grounders should slope inward at about 35 degrees.

Fill the space between the two rows of grounders with tightly compacted subsoil. Ram the soil down as hard as possible to form a solid core to the hedge, making sure to ram the soil tight against the grounders. Fill to the top of the lowest grounders and avoid leaving soil on top of them.

Place the hedge profile former against the end of the hedge and note the way the face curves inwards. Position the larger stones in rows, on top of the grounders. The outer edges of the stones are flush with the outer face of the grounders and the stones are tight against each other. Pack the center of the hedge as explained in the previous step.

Add further rows of inward slanting, progressively smaller, stones. When the hedge is a quarter of the intended height, the width should be three-quarters of the base width. At three-quarters of the full height, the width should be one-quarter of the base width. Build the rest of the hedge vertically. Keep checking the hedge profile against the profile former to ensure that it remains symmetrical and follows the correct curve.

Top the hedge with good topsoil and the sods rescued while initially preparing the ground. Firm the soil by ramming it down. Push wooden pegs through the sods to hold them in place if necessary.