raised bed garden | landscape blocks

How to Build a Raised Bed Garden with Landscape Blocks

landscape blocks

annual flowers

layout of the raised bed garden

Building a garden with landscape blocks is a rewarding DIY project that will enhance and beautify your home. The featured project was designed to solve problems with silver maple roots as well as creating an easy to maintain raised bed garden.

Choose a spot that has sufficient sun for the plants you want to grow. While vegetables require full sun, perennials (plants that go dormant for winter but return in spring) and annuals (one season flowers) can be chosen for any light conditions.

Lay out the design with a flexible hose or rope. Landscape blocks can easily create casual curves or formal geometric shapes. I had tree roots to navigate so my garden has a curvy, casual shape. A typical gardener can comfortably reach about 2 feet, installing a path through the middle will make it easy to tend the garden. The featured garden is approximately 18 feet by 12 feet, allowing room for four rows of flowers: tall in the back, medium flanking the path, and short annuals in the front.

Estimate the circumference (distance around) in feet by measuring the hose or rope with a tape measure. Decide on a height for your garden. This garden was planned at chair height to allow comfortable seating on the edge (4 courses + cap stone) A raised bed also helps keep the bunnies out.

Bring your measurements to the home store when you choose your landscape blocks. There are many colors and textures to choose from. The smaller sizes are easier to work with and weigh about 25 pounds each. Look for the ones with trapezoid shapes and guide bumps on top (like lego bricks) for easy assembly. The matching cap stones on top will give a finished look to your project.

trapezoid cap stones

When choosing a color, consider that some colors choices work better in different areas of the country - try to blend with your natural surroundings. Living in woodsy Minnesota, I chose a nice tree bark gray color to accentuate the garden plantings instead of emphasizing the planter.

Have the landscape bricks delivered and placed as close to your garden as possible. The home store can help estimate your order as there will likely be broken blocks on the pallet. The material cost for the blocks, trellis posts and delivery for the featured garden was about $700.00 in 2005.

Level the ground as best you can for the first course of blocks by laying a level on a 2x4. It is not necessary to lay a course underground for a project of this type. (Note: Retaining walls have different rules) Draw a chalk line from a squirt bottle to guide the original design. Lay them on the ground before digging, as you will likely need some adjusting as you go.

corner of raised bed garden

Landscape cloth keeps the soil in

addition to the garden

Alternating the trapezoid shapes creates curves or straight lines.  Blocks can be cut with a chisel and hammer for corners or ends.

Install fence posts if a trellis is desired.  Remember to sink below the frost line and account for the height of the raised bed.

Lay landscape cloth along the sides to keep the soil from filtering through the cracks. Due to the depth of this garden, there was no need to dig out the ground level sod before filling with soil. The cloth was rolled sideways on the wall and held in place with rocks as the soil was installed. Landscape cloth cuts easily with scissors to neatly trim the top.

Purchase good garden soil from a local contractor or landscape center. It costs more for garden soil (with peat or compost mixed in), but it will be worth it. The contractor can help guide you with estimating the cubic yards required (27 cubic feet per yard: cubic feet are L x H x W). The estimate for this 340 cubic foot project included the contractor wheelbarrowing it into the garden using wooden ramps. The total cost for soil and labor was about $600.00.

Add stairs and stepping-stones to make getting around the garden easier.

Finally, the fun part!  After adding more composted manure to the beds, plant your flowers.  Due to winter frost/thaw concerns, perennials are placed in the middle and the more susceptible garden edges are reserved for annuals. A climbing rose was added later using ground level pavers.

Tips:

Tree roots grow in the top 18 inches of soil and extend as far as the crown of the tree. Do not plan a tall landscape block garden around a tree as it would suffocate the roots.

The featured project took about 6 week-ends to complete. Take your time and take breaks.

Soil settles over time. In the beginning, completely fill the space with soil and hump it up a little in the middle. After two seasons it will be fully settled. Add amendments (peat, compost or manure) each spring around the base of the perennials and in the annual sections.

A raised bed garden requires more water than a ground level garden. Consider it to be a super sized pot.

Share|