Beyond concrete blocks: Granite offers stronger, better-looking garden walls

Concrete blocks remain a common choice for garden retaining walls because they are relatively cheap, strong and capable of lasting for decades. But granite offers a more natural appearance and high durability, making it an alternative for homeowners willing to pay more.

Granite formed over millions of years as magma cooled and crystallized. Its density and strength allow it to withstand outdoor conditions. The stone also offers a broad range of colors, including gray, blue-gray, yellow, brown, pink and red, depending on the quarry and its mineral composition.

The United States has several granite-producing areas. Georgia Gray, quarried in Elberton, Georgia, ranges from gray to blue-gray. Quarries in Vermont and Massachusetts offer other variations in color, grain size and texture. Granite can be cut into blocks of different sizes or used in irregular pieces, allowing builders to change the wall’s final appearance.

One construction method joins the stones with mortar. Another creates a dry-stone wall by carefully placing each piece without mortar, producing the look of old rural walls. House Digest recommends hiring a professional for retaining walls that must hold back substantial amounts of soil, because stability depends on more than the stone itself. Wall height, soil type, foundations and especially drainage all matter. Water trapped behind the wall increases pressure and can cause movement or collapse.

For a lower-cost solution, a wall can be built from concrete blocks and then covered with natural-granite slabs. The coverings are about one inch, or 2.5 centimeters, thick and attach with mortar. Because they use far less stone, they can create an appearance similar to solid granite at a reduced cost.