Stump grinding is the mechanical process of shredding a tree stump into small fragments, typically several inches below the soil surface. This action effectively removes the visible obstruction. However, it leaves behind a substantial volume of wood chips mixed with soil, along with a significant depression in the ground. The resulting messy, uneven area requires immediate attention before the space can be properly reclaimed. These cleanup and preparation steps are necessary to ensure the long-term health and stability of the landscape.
Managing the Wood Chip Debris
The grinder produces a large pile of wood chips and sawdust that must be managed immediately. A majority of the material should be removed from the immediate area to prevent future landscaping problems. This material is rich in carbon, which is an excellent addition to a compost pile when balanced with nitrogen-rich “green” materials like grass clippings or kitchen scraps.
The wood chips also serve well as a natural mulch for garden beds, helping to retain soil moisture and suppress weed growth. When using them as mulch, spread them in a layer no more than three to six inches deep, keeping them several inches away from the base of living plants. The chips should not be used as the primary fill material for the hole.
Preparing the Cavity for Refill
Once the bulk of the wood chips has been cleared, the cavity left by the grinding must be prepared for new material. The depth of the depression usually ranges from six to twelve inches below the surrounding grade. Use a shovel or rake to remove any remaining loose chunks of wood, sawdust, or large roots from the hole.
Any visible roots extending from the sides of the cavity should be removed to prevent them from sprouting new growth. It is important to check the area for proper water drainage, as the grinding process can sometimes compact the soil below the grinding depth. If water pools excessively, the compacted layer may need to be carefully loosened before filling.
Selecting and Applying Fill Material
The most important step for site recovery is filling the hole with a proper mix of materials to restore soil fertility and prevent settling. Using raw wood chips to fill the cavity is discouraged, especially if you intend to plant vegetation. Wood chips have a high carbon-to-nitrogen (C:N) ratio, and as they decompose underground, soil microbes rapidly consume nitrogen from the surrounding soil.
This microbial activity creates a temporary nitrogen deficiency, called “nitrogen robbing,” which leaves the area sterile for new plants. Instead, the cavity should be filled primarily with high-quality topsoil, or a mixture of topsoil and compost. The compost provides beneficial organic matter and nutrients, helping to counteract residual effects of wood decomposition.
The fill material must be added in layers and lightly compacted to remove air pockets and reduce future settling. After filling the hole, mound the new soil slightly higher than the surrounding grade, by one to two inches. This slight mounding accounts for the inevitable settling that will happen as the material consolidates.
Next Steps for Site Utilization
The final steps depend on the intended use of the reclaimed area.
Planting Grass
If the goal is to plant grass, the area should be leveled with the surrounding lawn after the initial settling period, typically a few weeks. New grass will benefit from a slow-release, nitrogen-rich starter fertilizer mixed into the top layer of new soil to combat localized nitrogen depletion.
Planting a New Tree
If the intention is to plant a new tree in the same spot, the preparation needs to be more thorough. This often requires excavating a larger hole to ensure the new tree’s roots do not immediately encounter residual wood chips or compacted soil. Dig the hole at least twice as wide as the root ball to encourage root growth into the native soil.
Hardscaping
For areas intended for hardscaping, such as a patio or walkway, the fill material must be compacted thoroughly to create a stable base that will not shift or sink over time.