What makes a stump hard to grind? There are three main factors that contribute to stump toughness:
- size
- hardness (species and greenness)
- access to the stump
As you’d expect, the sheer volume of the stump is going to be a big factor. It helps to think of this in terms of cubic volume: you’ve got surface area, and you’ve got depth.
Because stumps are roughly circular, a stump that’s only a couple inches wider increases the surface area (SA) significantly.
For instance, a stump that’s two feet in diameter has a SA of 452”.
A stump with a diameter of 2’-6”, though, has a SA of 706.86. That’s a difference of 254” square inches for a stump that seems only slightly bigger.
Then you factor in the depth: for every inch you go down, you have to multiply that surface area by 1. That’s why, in general, we recommend a conservative grind depth of 4-8”. This works for most situations, like planting grass or a garden over the grind site.
Hardness of the stump
That’s why you should make good and certain your stumps are dead if you’re not going to get them removed immediately. Softening them up will save us time and save you money when it comes to grinding. You can see this article on five ways to make sure your stump is dead.
The other factor that determines hardness is the species itself.
Hardness by common species in the Snohomish area
That’s why you should make good and certain your stumps are dead if you’re not going to get them removed immediately. Softening them up will save us time and save you money when it comes to grinding. You can see this article for five ways to make sure your stump is dead.
The other factor that determines hardness is the species itself.
Hardness by common species in the Snohomish area
The hardest woods you’re likely to ever come across are oak, mahogany, and hickory. The good news for homeowners in North America is that oak is the only one of the three that’s common on the continent. Here in Western Washington, the hardest woods you’re going to see a lot of are maple, oak, or walnut.
This list ranks common trees in the Puget Sound region from softest to hardest, according to the Janka scale:
- Black cottonwood
- Western Red cedar
- Pine
- Sitka
- Western Hemlock
- Alder
- Douglas fir
- Bigleaf maple
- Black walnut
- Oak
A notoriously hard tree that grows in our area is the Black walnut, sought after for it’s hardness and interesting aesthetics (this is probably the most valuable lumber tree in the area).
The cottonwood is both extremely common in the Puget Sound lowlands, and notoriously soft. Soft enough, in fact, to earn our rating of most dangerous tree.
