DIY Concrete Landscaping and Garden Borders

Concrete landscaping is made easy with these simple, clear instructions.

June 2014

Guide to Concrete (Creative Publishing International, 2008) takes readers through some of the most popular home concrete and masonry projects. Endorsed by Quikrete, this book includes tips and expert advice that can help readers save hundreds or thousands of dollars in their DIY home projects. In this excerpt from "Outdoor Home and Landscaping," concrete landscaping is the focus project, with an emphasis on creating great garden borders.

You can purchase this book from the MOTHER EARTH NEWS store: Guide to Concrete.

Book Cover

garden borders
You can cast garden borders just like these or change the mold dimensions to suit your own design. For stability, make sure the borders are at least 4 inches wide at the bottom.

Tools
• Saw
• Drill
• Concrete mixing tools
• Rubber mallet
• Concrete trowel
• 3/4 inch exterior-grade plywood or melamine-covered particleboard
• 2 inch coarse thread drywall screws

Materials
• Silicone caulk
• Vegetable oil or other release agent
• Crack-resistant concrete
• Plastic sheeting

Decorative and durable edging can have any number of uses in an outdoor home. It makes great garden borders, turf edges, driveway and parking curbs, decorative tree surrounds, and barriers for loose ground covers — just to list its most popular applications. You can buy factory-made edging in masonry and other materials, but few prefab products can match the stability and longevity of poured concrete, and none can have the personal touch of a custom casting.

In this project, you’ll learn how to cast your own border sections with poured concrete and a reusable wood mold. The process is so simple and the materials so inexpensive that you’ll feel free to experiment with different shapes and surface treatments. Coloring the concrete is an even easier option for a personal decorative effect (see QUIK-TIP, below).

The best all-around concrete to use for small casting projects like this is crack-resistant concrete, which contains small fibers to add strength to the finished product without the use of metal reinforcement. However, for any casting that’s less than 2 inch thick, use sand mix. This special concrete mix has no large aggregates, allowing it to form easily into smaller areas. Either type of concrete must cure for 48 hours before you can remove the mold; to speed your productivity, you may want to build more than one mold.

QUIK-TIP: For a personal touch, add liquid cement color to your concrete mix before pouring it into the mold. One 10 ounce bottle can color two 60 pound or 80 pound bags of concrete mix. Experiment with different proportions to find the right amount of color for your project.

building a mold for cast conrete

How to Build Cast Concrete Borders

cut the pieces for the mold
fasten the end panels
add trim or other elements 
1. Cut the pieces for the mold. Fasten the end blocking pieces flush with the ends of the side panels using pairs of 2 inch drywall screws driven through pilot holes. Fasten the bottom blocking to the side panels, flush along the bottom edges. 2. Fasten the end panels to the end blocking with 2 inch screws. Install the bottom panel with screws driven through the panel and into the bottom blocking. Make sure all panels and blocking are flush along the top and bottom edges. Note: You may need to leave one end open in order to work, as we have done here.
3. Add trim or other elements as desired for custom shaping effects. Here, we used crown molding, which we fastened to the blocking with finish nails using a nail set. Cover the screw heads on the inside of the mold with silicone caulk; then flatten to create a smooth, flat surface.
coat the inside of the mold
fill the mold with concrete
4. Coat the inside of the mold (all non-melamine parts) with clean vegetable oil or another release agent. Mix a batch of concrete following the product directions. An 80 pound bag of crack-resistant concrete will fill two of the molds. 5. Fill the mold with concrete. Settle the pour into the mold by pounding the work surface with a mallet or lifting the corners of the mold and tapping it onto the work surface.
screed or trowel the concrete
carefully disassemble the mold
6. Screed or trowel the concrete so it is flat and flush with the top of the mold. Cover the mold with plastic sheeting and let it cure undisturbed for 48 hours. 7. Carefully disassemble the mold by unscrewing the ends and bottom from the sides, as needed. Scrape, file, or grind any ragged edges for clean detailing in the finished piece. For maximum strength, set the casting in a shaded area and moist-cure it for three to five days, keeping it damp under plastic sheeting.

More Concrete Projects:

How to Make a Concrete Ramp
How to Mix Concrete
Setting Posts in Concrete


Reprinted with permission from Guide to Concrete: Masonry and Stucco Projects published by Creative Publishing International, 2008. Buy this book from our store: Guide to Concrete.

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