Drain spade vs post hole digger
Updated: October 2026
You are hoping one tool will both cut the hole and carry the soil out. A drain spade cuts a slot. A clamshell post-hole digger lifts loosened spoil. In ordinary garden soil or clay, a hole deeper than the blade needs that sequence, not a winner. Buy the blade to cut, the clamshell to lift, and both for a few fence posts in ordinary or clay soil. Buy the blade alone when you can still clean the channel. Buy the clamshell alone only in soil that is already soft, sandy or peaty. Prices sit on the [hole spade comparison](/hub/digging-tools/hole-spade). Peter F. compared the listings and public UK sources in October 2026. There was no lab test. A qualifying purchase can earn a commission at no extra cost to you.
You are hoping one tool will both cut the hole and carry the soil out. A drain spade cuts a slot. A clamshell post-hole digger lifts loosened spoil.
You are hoping one tool will both cut the hole and carry the soil out. A drain spade cuts a slot. A clamshell post-hole digger lifts loosened spoil. In ordinary garden soil or clay, a hole deeper than the blade needs that sequence, not a winner. Buy the blade to cut, the clamshell to lift, and both for a few fence posts in ordinary or clay soil. Buy the blade alone when you can still clean the channel. Buy the clamshell alone only in soil that is already soft, sandy or peaty. Prices sit on the hole spade comparison. Peter F. compared the listings and public UK sources in October 2026. There was no lab test. A qualifying purchase can earn a commission at no extra cost to you.
Our top picks
| Badge | Product | Job | Weight | Shaft | Note | Price | Offer |
|---|---|---|---|---|---|---|---|
| Best overall |  Spear & Jackson Spear & Jackson 2154HK draining shovel | Cuts a slot | 2.79 kg | Tubular steel, 711 mm | 9.4 | about £16.20 | View offer |
 Roughneck Roughneck drainage and post hole shovel | Cuts a slot | 1.98 kg | Fibreglass, 1070 mm | 9.4 | about £21.54 | View offer | |
 Roughneck Roughneck ROU68250 post hole digger | Lifts loose spoil | 5.2 kg | Fibreglass, 1500 mm | 9.4 | about £39.99 | View offer |
On this page
What each tool is for
A drain spade, trenching spade or grafting spade is one narrow blade. You drive it, pare the sides and scrape spoil while you can still reach. B&Q’s planting guide calls the drain spade the slim channel tool, next to a digging spade for beds and a border spade for edges. In this comparison the blades are the Roughneck drainage shovel, the Spear & Jackson 2154HK, the JCB Drain Master, the JCB fencing graft and the sectional Jardineer. They differ in forging and weight. They are still one family: a single edge that cuts.
A post-hole digger, as a shuv-holer, is two hinged blades. You drive them into soil that will give, open them to bite, and lift a plug. The clamshells here are the Neilsen CT1148, the Roughneck 68-250, the Spear & Jackson PHD-WH and the OLLIDOT. Reviews praise the PHD-WH and the Roughneck clamshell for lifting, and criticise both on hard ground and on dry spoil that falls out of the jaws. An auger is neither. If the picture is a helix, you are not in this pair. Steps sit on the how to use a post hole digger page.
When the drain spade is enough
A drain spade is enough for a shallow channel you can still empty with the blade: a land-drain slot, a cable route across a bed, the first part of a post hole you have not taken deep. Reviewers use these shovels because a full-width spade opens too much ground. Stay with the blade while each bite still comes out on the blade. You run out of enough when you are raking soil with the shaft, or when loose dry spoil falls off before you can lift it clear. A fence hole around the publisher figure of about 600 mm is usually past that point. Width and depth live on the hole spade for fence posts page.
When the clamshell is enough
The clamshell is enough in soft soil, sand, peat, or a hole a spade has already broken. Reviews of the ash PHD-WH and the heavy Roughneck often describe that second stage, around 600–900 mm or 40–90 cm, after the soil is loose. You bend less than with a short spade, at 4.13 kg or 5.2 kg before the spoil is in the jaws. It is not enough in unbroken clay, rubble or stones. The blades skid, twist or bend, and dry crumbs fall back in. A bar is the handbook answer. The Neilsen, 3.32 kg, still draws reviews that say it warps if you rotate it. The conservation handbooks say the clamshell is not strong enough to make the hole except in very soft soil, sand or peat. The OLLIDOT reviews include bending or breaking on early holes. That is a weak example of the type, not every clamshell.
The usual fence kit
A few fence posts in ordinary or clay soil are the both case. Cut with the drain or graft blade, break stones with a bar, and lift with the clamshell once the spade is fumbling. That is one weekend kit. The blade might be the lighter fibreglass drain shovel or the forged drainer. The lifter might be the Neilsen, the heavy Roughneck or the ash PHD-WH. Weight and price for that choice sit on the hole spade buying guide. The order does not change: blade first, jaws second. A long compacted run is an auger job, after a services check. Neither tool is a cable locator, and neither is insulated. A grafting spade replaces, or upgrades, the cutting blade. It does not replace the clamshell.
Common questions
What does each tool actually do?
The drain or grafting spade cuts a narrow slot and lifts soil only while the blade still reaches. The clamshell grabs loosened spoil from a deeper hole. UK handbook practice treats the clamshell as the second tool, except in soft soil, sand or peat. An auger is a drill, not either of these. A screw filed under post hole digger is a third tool, and it is not this pair.
Can I finish a post hole with only a drain spade?
You can finish a shallow hole or a trench you can still clean with the blade. A typical garden fence hole around 600 mm is usually deeper than that comfortable reach, so you end up dragging spoil with the shaft. People do it. It is slower, and it is why the clamshell exists. If the sides collapse because you are levering a wide bite, the hole is getting bigger than the post needs.
Can I start a clay hole with only a clamshell?
You can try, and the reviews and the handbooks say you should not. The jaws are for soil that is already loose. In clay they twist, stall or bend. Break the ground with a drain spade or a bar, then lift. The OLLIDOT’s early bend reports are the sharp version of starting with the lifter, not a verdict on every clamshell.
When is one tool enough?
The drain spade is enough for a channel or a hole the blade can still empty. The clamshell is enough when the ground is soft, sandy, peaty or already broken. A short run of fence posts in ordinary or clay soil is the two-tool job. A grafting spade replaces, or upgrades, the cutting blade. It does not replace the clamshell. Two lifters still leave you with nothing that cuts dry clay.
Where does a grafting spade sit in this pair?
On the blade side. A Newcastle-style graft such as the JCB Drain Master is a narrow forged spade with a tread, for trenches and stony clay. It cuts. It does not hinge. If you only buy the graft, you still want a lifter once the hole is deep. A bolted root shovel is a blade as well, and a weaker joint.
What about an auger?
An auger drills a post hole and it is the hire tool for a long compacted run. It is not a drain spade and not a clamshell. Retail pages sometimes file it under post hole digger, which is why the search feels muddled. Locate services before you switch it on. A powered auger has no business near a suspected cable route.
Do I need both for a short fence?
For a few posts in ordinary or clay soil, yes: the blade to start and the clamshell to lift, with a bar if you hit stone. For one shallow hole in a soft bed, the single tool that matches the soil is enough. Buy the pair before you buy a second pattern of the same tool. Two lifters still leave you with nothing that cuts dry clay.
Related pages
Sources
Public UK sources from the research digest. Prices, stars and review counts are the amazon.co.uk listing lines used in this comparison. We did not run a lab test.
- HSE — excavation and underground services (retrieved October 2026)
- HSE HSG47 — avoiding danger from underground services (retrieved October 2026)
- HSE CIS65 — excavating near underground services (retrieved October 2026)
- Energy Networks Association — Think before you dig (retrieved October 2026)
- BSI BS 3388:2004 — forks, shovels and spades (retrieved October 2026)
- Conservation Handbooks — hole digging for a post and wire fence (retrieved October 2026)
- Jacksons Fencing — how deep to dig fence posts (retrieved October 2026)
- Consumer Rights Act 2015 (retrieved October 2026)