Law, permission and conduct
How to Fill a Metal Detecting Hole Properly: Plugs, Turf and Leaving No Trace
Quick answer
Cut a three sided hinged plug with a serrated digger, fold it back on the hinge, put every crumb of loose soil on a mat rather than the grass, recover the target with a pinpointer, refill in the order the soil came out, fold the plug back and tread it flat. Done properly nothing is visible from standing height.
Hole filling is the single skill that decides whether detecting stays legal in your local parks. Wardens do not measure how many coins you found. They look at the grass. One visible scar on a sports field, one brown circle on a lawn, one plug that died because it dried out, and the ordinance changes for everybody. This is the least glamorous page on this site and the most important one after the law.
The technique is the plug: a three sided cut that leaves a hinge of living root, folded back like a lid and folded down again afterwards. It takes about twenty seconds longer than digging a hole and it is the difference between a site that closes and one that does not. The code of conduct treats it as non-negotiable, and so does every club worth joining.
Top pick
Lesche Digging Tool (right handed)
A serrated blade cuts the root mat cleanly instead of tearing it, which is the whole reason a plug survives being put back.
Price was accurate when this page was compiled and changes often.
On this page
What does a proper plug look like?
- Pinpoint before you cut. Narrow the target down with the detector and then with a pinpointer, so the plug can be small. A four inch plug that lands on the target beats an eight inch plug that misses it.
- Cut three sides, not four. Drive the digger in vertically to the full blade depth and cut a U or a square with one side left uncut. That uncut side is the hinge, and it is what keeps the turf alive.
- Angle the blade slightly inwards. A plug with slightly undercut edges drops back into its own socket and sits flush rather than proud.
- Fold the plug back on the hinge. Lift and fold it over like a lid, grass side up, and leave it attached. Never lift a plug out and set it upside down on the grass.
- Put loose soil on a mat or in the pouch. Every crumb that lands on the surrounding grass is a brown patch in a week. A small mat, a cloth or the lid of the pouch is enough.
- Recover the target from the side wall. Probe the hole and the plug with the pinpointer rather than widening the hole blindly. Most missed targets are in the plug itself.
- Refill in reverse order. Subsoil back first, then topsoil, then fold the plug down. Soil layers put back in the wrong order kill the grass more often than the cut does.
- Tread it and check from standing height. Press it down firmly with a boot, water it if the ground is dry and you can, and then stand up and look. If you can see it, fix it now.
Which tool suits which ground?
Tool choice is mostly about the root mat and the soil. Turf needs a blade that cuts roots rather than tearing them, hard ground needs leverage, and beaches need something that sifts rather than cuts.
Manicured turf needs a serrated hand digger cutting a small hinged plug, hard pasture and relic ground justify a serrated T-handle shovel, and sand needs a scoop rather than any kind of blade.
| Ground | Tool | Typical plug | Notes |
|---|---|---|---|
| Municipal park lawn and sports turf | Serrated hand digger | Small hinged plug, blade depth only | Many parks ban anything larger, and some ban digging outright |
| Garden and flower bed | Stiff serrated trowel | Small plug or a simple slot | Soft soil, so the risk is soil on the surrounding surface |
| Pasture and rough grass | Hand digger with a sheath | Hinged plug | The sheath matters because these blades are genuinely sharp |
| Hard or stony ground | 31 inch serrated T-handle shovel | Larger plug, cut square | Leverage does the work, so you are not levering a hand tool to failure |
| Ploughed field | Full size serrated shovel | Loose soil, no plug to preserve | Still backfill and tread, because a tractor tyre finds every hole |
| Long walk in to a site | 18 inch T-handle | Hinged plug | Straps to a pack, which is why it gets carried rather than left in the car |
| Dry and wet sand | Stainless sand scoop | No plug, sift and refill | A blade in sand is slow and pointless, and a scoop drains |
| Salt water and surf | Titanium scoop | No plug | Titanium does not corrode in salt and does not sound off on the detector |
Tool descriptions are taken from the manufacturer listings for each product. Which tools a given site permits is a local rule, so check before you arrive.
Why do plugs die, and how do you stop it?
Three causes, in order. The first is drying: a plug left folded back in the sun for ten minutes while you hunt for the target loses moisture from the exposed roots, and it browns a week later. Work quickly, and fold the plug back down while you check the target rather than leaving it open. The second is soil in the wrong order, which buries the topsoil and puts subsoil against the root mat where nothing grows. The third is a plug that is not trodden back down, so air sits under the roots and dries them from beneath.
The fix for all three is speed and a pinpointer. A Garrett Pro-Pointer AT turns a two minute excavation into a twenty second one, which is the single biggest improvement you can make to how your holes look, and the Minelab PRO-FIND 40 does the same job with a ferrous tone. The beginner guide puts a pinpointer above almost every other accessory for exactly this reason.
What about ground where a plug is not possible?
Sand takes a scoop, not a blade: you sift the target out and the hole collapses behind you, though on a dry beach you should still kick the mound flat because an ankle goes into an open scoop hole very easily. Gravel and stony ground will not hold a plug, so cut square, keep the spoil on a mat and repack it firmly. Ploughed fields have no turf to preserve, but they still need backfilling, because an open hole is a hazard to livestock and to machinery.
Frozen ground is the case where the honest answer is to go home. You cannot cut a clean plug in frozen turf, the root mat shatters rather than folds, and the scar will still be there in spring. Beach hunting is the usual alternative when inland ground is frozen or baked hard, which is part of why beaches carry the winter for so many detectorists.
How do you check your own work honestly?
Stand up straight and look at where you dug from normal walking height, not from your knees. That is the angle a warden or a groundsman sees. Then look back across the site into the light before you leave, because low sun shows every raised plug edge that you will not see from directly above. If a plug is proud, tread it again. If soil is on the grass, brush it into the plug.
Carry a light so that the last hour of a session is not the one that produces the bad plug. A LHKNL Rechargeable LED Headlamp keeps both hands free for exactly this, and NoCry Professional Gel Knee Pads are the accessory most people buy second and wish they had bought first, because you kneel for every single target. The number of holes a session actually involves is worth putting a figure on with the dig time budget calculator before you promise a landowner you will be finished by lunch.
Sources
- Published codes of practice from national detecting associations
- Lesche, CKG and RTG manufacturer product listings for the tools named above
- Garrett Pro-Pointer AT product specifications
Frequently asked questions
What is a plug and why does it matter?
A plug is a three sided cut in turf that leaves one side uncut as a hinge, so the turf folds back like a lid and never separates from its own roots. It matters because a plug put back the same day usually survives, while turf cut free on all four sides frequently dies and leaves a brown patch. That patch is what closes parks to detecting.
How big should a detecting hole be?
As small as the target allows, which in practice means as small as your pinpointing allows. Narrow the signal with the detector, narrow it again with a pinpointer, and cut a plug a little larger than the blade rather than a spade width. On manicured turf many park rules set a maximum size, so check the local ordinance before you arrive rather than after somebody complains.
Do I need a pinpointer just to fill holes better?
It is the accessory that improves your holes most, which is a strange thing to say about a detecting tool. A pinpointer cuts recovery time sharply, and shorter recovery means the plug spends less time folded back and drying out. It also stops you widening a hole blindly while hunting for a target that is usually sitting in the plug you already lifted.
What do I do with the soil I take out?
Put it on a small mat, a cloth or the lid of your pouch, never on the surrounding grass. Loose soil scattered around the hole smothers the grass and leaves a ring that is visible long after the plug itself has healed. Refill in the order the soil came out, subsoil first and topsoil last, so the root mat sits against soil it can actually grow in.
Can I dig on a beach the same way?
No, and you should not try. Sand will not hold a plug, so you use a scoop, sift the target out and let the hole collapse. On dry sand still kick the mound flat before you move on, because an open scoop hole is an easy way for somebody to turn an ankle. In wet sand and the surf the tide does the tidying, but the same habit is worth keeping.
Researched, not professional advice. This page is compiled from published specifications, manuals and owner-review consensus, not hands-on testing. Target ID numbers, depth figures and settings vary with soil chemistry, moisture, target size, depth, orientation and firmware version, so treat every figure here as a starting point and verify it against your own machine's manual and your own ground. As an Amazon Associate we earn from qualifying purchases.