Boulder Walls Landscaping | Ideas & How To

We've seen a ton of buzz and questions around using boulders as walls in landscaping, so we thought we'd tackle the conversation head on. At our house in Colorado, we actually have garden boxes (they also serve as seating) about 2-3ft high made of rocks and boulders from Lyons, Colorado - these things were chiseled by hand to form a dry stack wall and they look great, especially as moss and lichen start to add color and character.

But that's not to say your boulder wall has to be that painstaking! 

(This is ours - see above)

Ten ideas for boulder wall applications:

Retaining walls: Boulder walls can be used to create terraces on sloped properties, prevent soil erosion, and provide additional usable space in a garden or yard.

Garden boxes: Boulder walls can be used to create raised garden beds for flowers, vegetables, or herbs, providing a natural and attractive border that helps with drainage and soil retention.

Seating areas: Use boulder walls to create a natural seating area in your garden or patio by building a low wall around the perimeter and topping it with flat boulders or flagstones.

Water features: Boulder walls can be incorporated into waterfalls, ponds, or streams, creating a natural-looking and visually appealing landscape feature.
Fire pits: Enclose a fire pit area with a boulder wall to provide a cozy, natural seating area and windbreak for outdoor gatherings.

Property borders: Boulder walls can be used to define property boundaries or separate different areas within a landscape, providing a natural and aesthetically pleasing alternative to fences.

Outdoor kitchens: Integrate a boulder wall into an outdoor kitchen design as a decorative and functional element, such as a countertop or bar.
Wildlife habitat: Create a boulder wall in your garden to provide a habitat for small animals, insects, and birds, promoting local biodiversity.

Pathways and steps: Use boulder walls to create natural-looking borders or supports for garden pathways and steps.

Decorative accents: Boulder walls can be built as standalone features in a garden or yard to add visual interest, texture, and dimension to the landscape.

Materials list for building a boulder wall:

• Boulders of various sizes, shapes, and colors
• Gravel or crushed stone
• Landscape fabric (optional)
• Perforated drain pipe (for retaining walls)
• Shovel and/or excavator
• Level
• Wheelbarrow
• Gloves and safety gear
• Rubber mallet
• PVC pipes or wooden stakes (for marking the wall layout)

Detailed steps for building a boulder wall:

• Determine the purpose, location, and dimensions of the boulder wall.
• Sketch a design or create a detailed plan, including the wall's layout, height, and desired boulder arrangement.
• Obtain necessary permits and call 811 to locate underground utilities.
• Choose boulders that match your design requirements, ensuring a mix of sizes, shapes, and colors.
• Pro tip: When designing the wall, consider the natural shape of the boulders and aim for a balanced composition that mimics how boulders would appear in nature.

• Use wooden stakes or PVC pipes to mark the wall's layout, including its width and height.
• Remove any vegetation, rocks, or debris from the area.
• Excavate a trench for the wall's foundation, making it 6-12 inches deep and wide enough to accommodate the largest boulders.
• Pro tip: If building on a slope, consider creating a stepped foundation, which allows for easier leveling and better stability.

• Fill the trench with a 4-6 inch layer of gravel or crushed stone, compacting it to create a stable base.
• Level the gravel using a straightedge or pipes, ensuring a consistent and stable surface for the boulders.
• Pro tip: If building a retaining wall, consider using a layer of landscape fabric beneath the gravel to help prevent soil migration and improve drainage.

• Start with the largest, flattest boulders and position them in the trench, ensuring they are firmly seated and level.
• Use a rubber mallet to gently tap the boulders into place, adjusting them as needed for a secure fit.
• Check each boulder for level, both side-to-side and front-to-back, before moving on to the next one.
• Fill any gaps between the boulders with gravel or crushed stone.
• Pro tip: Arrange the boulders so that the edges and corners are touching, creating a stronger bond and more stable wall.

• Continue placing boulders on top of the base layer, interlocking them with the layer below for added stability.
• Use smaller rocks or shims to fill gaps between boulders, ensuring a snug and secure fit.
• Step the wall back slightly as it gets higher, creating a slight angle to help resist pressure from behind (especially important for retaining walls).
• Pro tip: Stagger the boulders' vertical joints, similar to a brick wall pattern, to improve the wall's structural integrity and visual appeal.

• Place a perforated drain pipe behind the base of the wall, ensuring it slopes away from the wall to divert water.
• Cover the drain pipe with a layer of gravel or crushed stone, which aids in drainage and prevents clogging.
• Backfill the area behind the wall with a mix of soil and gravel, compacting it in layers as you go to provide additional support.
• Pro tip: Use landscape fabric behind the boulders to prevent soil from washing through the gaps and maintain proper drainage.

Frequently Asked Questions:

Q: How high can a boulder wall be built?
A: The maximum height of a boulder wall depends on factors such as the size and weight of the boulders, the purpose of the wall, and local regulations. Generally, boulder walls under 3-4 feet in height are considered safe for DIY projects. Taller walls or retaining walls on steep slopes may require professional engineering and construction.

Q: Can I use a boulder wall to support a driveway or parking area?
A: Yes, but it's important to consult with a professional engineer to ensure the wall is designed and built to withstand the additional load and pressure from vehicles.

Q: How do I maintain a boulder wall?
A: Boulder walls require minimal maintenance. Periodically inspect the wall for signs of movement, shifting, or erosion, and address any issues promptly. Remove any debris or vegetation that accumulates around the wall to prevent damage and maintain proper drainage.

Q: How much does it cost to build a boulder wall?
A: The cost of building a boulder wall depends on factors such as the size of the wall, the type and quantity of boulders, and the complexity of the project. Costs can range from $25 to $60 per square foot or more, depending on these variables and local labor rates.

Q: How do I choose the right boulders for my wall?
A: Select boulders that are large and heavy enough to support the weight of the wall, have flat surfaces for easier stacking and stability, and offer a mix of sizes, shapes, and colors for visual appeal.

Q: Can I build a boulder wall on a slope?
A: Yes, but it may require additional planning and engineering, such as creating a stepped foundation, to ensure the wall is stable and functional.

Q: What types of plants can be incorporated into a boulder wall?
A: Consider using creeping or trailing plants, groundcovers, and drought-tolerant species that complement the natural look of the boulder wall. Alpine plants, succulents, and native grasses are all excellent choices.

Q: How can I make my boulder wall more visually interesting?
A: Use boulders with a variety of shapes, sizes, and colors to create texture and visual interest. Incorporate plants, water features, or lighting to add dimension and ambiance.

Q: Can I build a boulder wall myself, or should I hire a professional?
A: Building a small, decorative boulder wall can be a manageable DIY project, but larger walls or those that serve a structural purpose, such as retaining walls, may require professional design and construction. If you're unsure, you can always use the chat feature in the bottom right of the screen or schedule a free consult with one of us from LessLawn! 

Q: Are there any safety concerns when building a boulder wall?
A: Building a boulder wall can be physically demanding and may require heavy lifting, so use proper lifting techniques and safety equipment. Be mindful of potential hazards, such as falling rocks or unstable ground, and take necessary precautions to ensure a safe work environment.