How to Anchor Posts in the Ground for an Arbor
The post anchoring procedure for arbor construction mirrors that of fences and basic post-and-beam structures. Although there are several options for anchoring posts, the simplest and most common method involves plunging the post directly into a post-hole filled with concrete. However, because this method leaves the post's butt exposed to ground moisture and pests, builders use decay-resistant lumber to build arbor posts, such as pressure-treated lumber or redwood. With posts properly set, the primary, load-bearing component of the arbor is complete.
Use a shovel or post-hole digger to dig the hole for your arbor's posts. Although hole size varies according to project, standard post holes for 4-inch posts are approximately 10 inches in diameter and approximately 2 feet deep, or deep enough to engulf one-third of the post. Pound stakes around the perimeter of the holes with a mallet. Add an approximately 6-inch thick layer of gravel to each post hole.
Place a post into one of the holes and have a helper hold the post upright. Place a post level against the side of the post and adjust the post's position until it stands plumb. Attach one side of a piece of scrap lumber to each stake with a hammer and nails. Attach the opposite side of each piece of scrap lumber to the post to brace the post in a plumb position. Level and brace the second arbor post.
Pour dry post-hole cement into each post hole. Post-hole cement is specially formulated to absorb moisture from the air and the ground; add the dry mixture to the hole and lightly agitate the mix with a piece of scrap lumber to eliminate air pockets. Add a sprinkling of water to the top of the post-hole mix; do not fully wet the mix. Leave the concrete to set for at least 24 hours to 48 hours before removing the braces.
Things You Will Need
- Shovel or post-hole digger
- Post level
- Scrap lumber
- Post-hole cement
- If you prefer to use regular concrete mix, simply mix the concrete with water in a wheelbarrow prior to pouring around the braced post.
- Post-hole cement does not require mixing.
- University of Florida Extension; Arbor, Trellis, or Pergola? What's in Your Garden? Dictionary of Garden Structures and Plant Forms; Gail Hansen
- University of Minnesota Extension; Building Overhead Structures, Pergolas and Arbors; Joanie Somerville, Stephanie Jutila and Michael Sonnek
- University of Minnesota Extension; Deck and Outdoor Structure Footings; Jeff Fahrenholz