What each one actually does
Grinding. A rotating carbide-toothed wheel sweeps across the stump, taking a few millimetres per pass, working down and out until the stump and the upper root plate are wood chip. Typical depth is 200 to 300 millimetres below grade, more if asked for. Nothing is pulled out of the ground. The lateral roots remain and decay in place over several years.
Removal. An excavator or bobcat digs a ring around the stump, exposing and cutting the major lateral roots, then levers the whole root plate out. It is cut down, loaded and carted away, and the void is backfilled with clean fill in compacted layers.
They are different machines, different day rates and different outcomes.
The decision, in one question
Is anything structural going over that spot?
A concrete slab, a pool shell, a retaining wall footing, a driveway, a new fence footing, a sewer or stormwater trench. If yes, you need removal. Decaying roots under a structure lose volume and take the surface down with them, and no builder will pour over them.
If the ground is going back to lawn, mulch, garden bed or plain dirt, grinding is enough, costs a fraction as much, and disturbs a far smaller area.
Where grinding wins
Cheaper, faster, tidier. One machine, one operator, often less than an hour per stump. Narrow-access machines fold to around 750 millimetres and walk through a standard side gate, which matters enormously on the tight blocks at Umina Beach and Woy Woy.
It also leaves the surrounding ground largely intact — no excavator tracking across the lawn, no spoil heap, no truck.
And on a steep block it is often the safer engineering choice. A large root plate on a terraced site at Green Point may be helping hold a bank together, and ripping it out can undermine a retaining wall.
Where removal wins
Anywhere a structure is going over the top, and in three other cases.
Persistent suckering species. Camphor laurel, privet, willow and coral tree can regenerate from surviving lateral roots after grinding. On the Central Coast camphor laurel is the common offender in older gardens.
Root disease. Where Armillaria root rot is present, infected stumps left in the ground can pass it to neighbouring trees through root contact. Full removal breaks that chain.
Bushfire asset protection work, where stump and root material is part of the specified clearing.
The cost gap
Grinding is priced by stump diameter, number of stumps, depth and access. Removal is priced by machine time, spoil volume, cartage and imported fill, and it climbs steeply where a machine cannot reach and the work has to be done by hand.
On a tight Central Coast block with no machine access, hand excavation of a mature root plate can cost several times the grinding price for the same stump.
Whichever you choose, book it early
The cheapest version of either job is on the same mobilisation as the tree removal, while the crew is on site and the gates are open. A second visit months later is a second mobilisation.
Full detail on each is on the stump grinding and stump removal service pages, with local soil notes in the regional grinding guide.
Frequently asked questions
Which is cheaper, grinding or full removal?
Grinding, substantially, and it is the right answer for most residential situations. Grinding uses one machine and one operator and is often finished in under an hour per stump. Full removal needs an excavator or bobcat, somewhere to stockpile spoil, a truck to cart the root ball away and clean fill to backfill the void, and it disturbs a much wider area.
Does grinding remove the roots?
No, and this is the key difference. Grinding removes the stump and the top of the root plate. The lateral roots stay in the ground and decompose over the following years. For turf, mulch or a garden bed that is entirely adequate. Under a slab, a footing, a driveway or a trench it is not, because decaying roots lose volume and the surface follows them down.
How long do the roots take to rot after grinding?
Several years, depending on species, soil moisture and root diameter. Small feeder roots break down within a year or two. Large laterals from a mature eucalypt can take five years or more, and in the dry sandy soils on the Peninsula it takes longer than in the damp lake-edge flats. It is not a reason to avoid grinding unless you are building over the spot.
Can I plant a new tree in the same hole?
Not directly into the grindings. Decomposing wood chip ties up soil nitrogen and a new tree planted into it will struggle. Either excavate the chip and replace it with soil in the planting hole, or plant nearby and leave the ground a season or two to settle. Turf will establish over topsoil laid on settled chip without trouble.