When installing a new fence or deck, you’ll likely need to dig holes for the posts. This task is much easier with a post-hole digger, which helps to create accurate and deep holes for secure installation. In the video above, This Old House landscaping contractor Roger Cook explains how to use a manual post-hole digger to create a strong foundation for your outdoor builds.
Types of Post-Hole Diggers
Post-hole diggers are specialized tools designed to create narrow, deep holes for setting posts. They come in manual and powered varieties, each with its advantages and specific uses.
Why Not Just Use a Shovel? A lot of people reach for a regular pointed shovel to dig a post hole, and while you can get started that way near the top, it quickly becomes counterproductive. As the hole deepens, you have to widen it significantly just to keep digging — creating far more work for yourself. Post-hole diggers solve this by removing soil from a narrow column, keeping the hole tight and minimizing the amount of dirt you move and the concrete you’ll need to fill around the post.
Clamshell vs. Gibbs Digger: The standard clamshell post-hole digger has twin blades and two handles — you drive it into the ground, spread the handles apart, and lift out the soil. But as This Old House landscape contractor Roger Cook has noted, once you get down deep with a clamshell digger, there isn’t enough room to spread the blades wide enough, and “the dirt just slips right out between the clam.” For deep, narrow holes, a Gibbs-style digger with a swiveling head scoops out soil without widening the opening. As Roger explains, the single-blade design is “the choice of the professional fence guys. This is what they use.”
Manual Post-Hole Diggers
Manual post-hole diggers are suitable for most residential use cases. They consist of two long handles connected to a pair of curved blades that close together to grab and lift soil. These tools are good for smaller jobs and allow the user to control the digging process.
Pro Tip: Roger Cook, This Old House landscape contractor, prefers a lesser-known alternative called a Boston digger: “After watching it in action for a few minutes, people quickly realize how much easier it is to use than a typical post-hole digger with scissored handles.” Roger notes that while standard clamshell diggers lose their grip on soil as the hole gets deeper—because there isn’t enough room to spread the handles wide—a Boston digger can cut straight-sided holes nearly 4 feet deep.
Powered Post-Hole Diggers
For larger projects or harder soil, powered post-hole diggers can save time. These tools use a motor to drive an auger into the ground, quickly creating deep holes without the physical effort required by manual diggers. They’re particularly useful for professional landscapers or contractors who need to dig multiple holes quickly. They also work well for extensive fencing or deck installations.
For this guide, we’ll focus on manual post-hole diggers. Ensure the blades of your post-hole digger are sharp and designed for the soil type you’ll be working in. Narrow blades are good for digging in hard or rocky soil, while wider blades are better for soft or loamy soil. Longer handles provide better leverage, making it easier to dig deep holes with less effort.
Prepare to Dig Your Post
First, get your materials ready. In addition to your post-hole digger, you’ll need these tools:
- Bucket for removing loose soil
- Level
- Shovel
- String line
- Tape measure
Mark the Holes
Use stakes and string to outline the fence or deck perimeter to ensure straight lines and consistent spacing. Mark each post location with spray paint or a small flag. Proper marking helps avoid mistakes during digging. Double-check measurements for proper spacing between posts to maintain structural integrity.
Safety Precautions
Before you start digging, take the following precautions:
- Check for underground utilities before digging to avoid damaging pipes or cables.
- Use safety glasses to shield your eyes from flying debris.
- Wear closed-toe shoes with good traction.
- Wear sturdy work gloves to protect your hands.
- Keep children and pets away from where you’re working.
Pro Tip: Roger Cook, This Old House landscape contractor, cautions: “Never, ever dig without knowing what’s in the ground. I’ve seen people do some serious damage to themselves and their property.” Before breaking ground, call 811 or your local one-call center so utility companies can send representatives to mark the locations of underground phone, cable, and gas lines.
Using a Manual Post-Hole Digger
First, remove any rocks or debris where you’ll be digging to avoid damaging your tools or having objects fly up. Then, use these tips when operating the manual post-hole digger to make the process easier and more accurate.
Proper Stance and Grip
Stand with your feet shoulder-width apart, straddling the marked hole location. Grip the handles on the outside to avoid pinching your hands. Keep your back straight, and use your legs for power.
Maintaining this stance and grip reduces strain on your back and arms, allowing you to work more efficiently.
Digging Technique
The following techniques guarantee that the hole remains narrow, preventing unnecessary work and saving you time and effort:
- Raise the digger above your head.
- Drive the blades straight down into the soil.
- Spread the handles apart to close the blades around the soil.
- Lift the digger and deposit the soil on one side of the hole.
- Repeat the process, gradually working your way deeper.
Let your body weight assist in pushing the blades into the ground, especially in hard soil. This reduces strain on your arms and shoulders.
Tips for Efficient Digging
- Start with shallow scoops and gradually go deeper as the hole forms.
- Rotate the digger slightly between plunges to break up the soil.
- If you hit a rock or root, turn the blades to work around the obstruction. Persistent clogs can be resolved with a digging bar.
- Keep the hole as narrow as possible to minimize unnecessary digging. Narrow holes require less concrete and provide better post stability.
Achieve the Proper Depth
As Cook mentions, a general rule is to dig to half the height of the fence above ground.
Measuring Hole Depth
Use these methods to maintain consistent depth, which is essential for structural integrity:
- Mark your desired depth on the post-hole digger handle.
- Use a tape measure to check the hole depth periodically.
- Consider using a post-hole digger with depth markings on the handles.
Adjusting for Different Soil Types
Different soil conditions may require adjustments to your digging technique:
- In sandy soil, you may need to dig deeper for stability.
- Clay soil can be challenging and may require clearing blades frequently.
- Rocky soil might require using a digging bar or powered auger.
Post Hole Finishing Touches
Once you’ve reached the desired depth, follow the below steps to finalize the project.
Clean Out the Hole
Remove any loose soil from the bottom of the hole. This creates a solid base for your post or concrete footing. You can use a trowel or small shovel for this task.
Make It Level
Use a level to make sure the sides of the hole are plumb, maintaining the vertical alignment of your posts.
Prepare for Post Installation
If you’re setting posts in concrete, take these steps:
- Add a thin layer of gravel at the bottom of the hole for drainage. This prevents water from pooling around the base, which can cause rot.
- Center the post in the hole.
- Use temporary braces to hold the post in place while the concrete sets. Bracing prevents the post from shifting as the concrete hardens.
Tips for Concrete Setting
When working with concrete, follow these tips:
- Mix your concrete to a thick, consistent texture. This helps it cure properly and provides a strong hold.
- Pour concrete slowly to avoid air pockets, which can weaken the base.
- Allow the concrete to set for at least 24 hours before attaching any fence panels or structure.
