Cairns are usually made from rocks or smooth stones. I have access to more branches than rocks or stones so I adapted. You may have seen what I am calling a branch cairn in a magazine. The idea is not mine but I thought I would share how I made mine. The original assembly method proved to have drawbacks so I rebuilt the cairn. This is why there is a blend of photos.
24-36 fairly straight branches about 24"-36" long x 1" diameter
PVC pipe 24"-36" long 3/4" diameter
Rebar 36"-48" long x 3/8" diameter
Flat rocks or stones
Rope or twine (optional)
Paint, black or dark brown
Lopper or tree saw (for cutting branches)
Measuring tape or yardstick
Saw (for cutting the branches to length)
Hot melt glue gun and glue sticks
Sledge or heavy hammer
Step 1: Preparing the Branches
The branches need to be fairly straight. While you are doing some heavy pruning of overgrown shrubs, save the straight pieces that are about 1" in diameter. My branches are from dogwoods but water sprouts from apple trees can also work well.
Assuming your branch cairn will be 24" tall, cut a piece to length and use it as your master. Use the master and mark all your branches for cutting. Also mark the PVC pipe for cutting. It should be about 2" longer than the branches. The extra length will extend from the bottom of the finished bundle to keep the wood off the ground to help prevent rot. Cut all the branches and the PVC to length. A power saw will speed up the process but a hand saw will work just fine. Paint the PVC pipe and let the paint dry. This will help the PVC blend in with the color of the branches.
Step 2: Assembly
The original assembly method was to simply make a bundle of branches with the PVC roughly centered. They were held together, top and bottom, with copper wire. Over time, wind and gravity caused some shifting so I decided to try another approach. The bundle was disassembled and rebuilt in a more secure manner.
Position the PVC and a branch so that the tops align and you have at least two places where they touch. Apply a 1" glue strip near the top to join the branch and PVC. When the glue hardens add another bead of glue to join the branch and PVC near the bottom. Continue to add branches, making sure the tops align and rotating the bundle as you add branches. Keep the PVC roughly centered. To add interest, wrap a 2-3" section with twine, thin rope or cord.
Pick a location for the structure in your garden. Drive the rebar into the soil at least a foot and deep enough so that the bundle will hide it. Slide the PVC in the bundle over the rebar. Add some rocks or flat stones to the top to complete your cairn.