Stump grinding removes the visible portion of a tree, reducing the stump to wood chips a few inches below the soil line. While this creates a clean surface for landscaping or construction, the extensive underground root system remains intact. Roots can stretch many feet beyond the original trunk, and their physical presence can interfere with future planting or hardscaping. Removing this remaining root mass is a separate, often labor-intensive task necessary for complete site reclamation.
Evaluating the Root System
Before attempting removal, assess the remaining root system to determine the most effective strategy. Tree roots spread far beyond the drip line; the largest lateral roots can extend 4 to 12 feet or more from the former trunk. Using a probe or shovel, determine the depth and radius of the major roots to inform whether manual extraction or a decay-accelerating method is appropriate.
The composition of the wood also influences the removal method, as different tree species decay at varying rates. Hardwood species like oak and maple take significantly longer to break down naturally than softer woods, such as pine. This assessment is important near underground utilities or paved areas, where physical extraction poses a risk, making a slower, decay-based approach preferable.
Manual Methods for Extracting Remaining Roots
Physical removal is the quickest way to eliminate the root mass, though it requires significant effort and specialized tools. Begin by using a pointed shovel to clear the soil and wood chips from around the primary lateral roots, exposing them. A strong flow of water can also wash away the soil, revealing the full extent of the buried root structure.
The exposed roots must then be cut into manageable segments for removal. A mattock or an iron digging bar is effective for chopping through smaller roots, while a root saw or a reciprocating saw works well for thicker sections. Once cut, use a shovel or pry bar to lever the segments out of the ground, working outwards from the original stump location. Always wear safety gear, including eye protection, and confirm the location of any underground utility lines before beginning deep digging or cutting.
Using Chemical and Natural Aids for Decay
For large or deep root systems where manual labor is impractical, the natural decomposition process can be accelerated using chemical or natural aids. Wood naturally has a high carbon-to-nitrogen ratio, which slows decay; introducing nitrogen-rich substances helps feed the fungi and bacteria that break down the wood fibers. High-nitrogen fertilizer, blood meal, or composted manure can be applied to holes drilled deep into the remaining root fragments to stimulate microbial activity.
Commercial stump removal products often contain potassium nitrate, which increases the nitrogen content and speeds up the decomposition timeline, resulting in decay within several months. Alternatively, rock salt or Epsom salt (magnesium sulfate) can be used, which draw moisture out of the wood, causing dehydration and making it susceptible to microbial attack. After applying these agents, keep the area moist and covered with a tarp or mulch to retain warmth and humidity, creating an optimal environment for decay. While these methods require patience, often taking six months to a year, they are less disruptive to the surrounding landscape.
Preventing Sprouting and Future Regrowth
A problem following grinding is the potential for remaining living roots to generate new shoots or suckers, known as regrowth. Species like willow, poplar, and certain fruit trees are prone to this because their root systems retain significant energy reserves. The most effective control involves the immediate application of a systemic herbicide, such as glyphosate or triclopyr, directly to the freshly cut surface of the remaining roots.
The herbicide must be applied quickly, ideally within an hour of grinding, to the exposed cambium layer. This allows the chemicals to be translocated throughout the root system before the wound seals. For roots that sprout later, cut back the new shoots and paint the concentrated herbicide onto the fresh cut surface. Consistent monitoring and prompt treatment of emerging sprouts are necessary to exhaust the root’s stored energy and ensure complete termination.