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Removing a tree stump with potassium nitrate

Grinding is fast but expensive. If you can wait a few weeks, the drill-and-fill method lets you break down a stump yourself for the cost of a bag of powder.

By the Blue Grove team · 6 min read

How it works

Potassium nitrate is a source of nitrogen. Packed into a stump with water, it speeds up the natural decay of the wood, so the stump softens and breaks apart much sooner than it would on its own. It is the same active ingredient used in many store-bought stump removers.

What you need

  • Potassium nitrate powder
  • A drill with a large spade or auger bit (about 1 inch)
  • A chainsaw or handsaw (optional, to cut the stump low)
  • Water, a tarp and safety glasses
  • An axe or mattock for the final step

Step by step

  1. Cut the stump as close to the ground as you safely can.
  2. Drill holes about 8 to 12 inches deep across the top, spaced 3 to 4 inches apart and set in about 3 inches from the edge.
  3. Drill a few angled holes into the sides so they meet the vertical holes.
  4. Fill each hole with potassium nitrate, then slowly add water until the powder dissolves.
  5. Cover the stump with a tarp to hold in moisture, and keep it damp.
  6. Check every couple of weeks. When the wood turns soft and spongy, usually after 4 to 6 weeks, break it apart with an axe or mattock.
Good Batch Potassium Nitrate
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Safety basics

Potassium nitrate is an oxidizer, so it makes things burn more intensely. Never light a treated stump, and keep it away from open flames, grills and fire pits. Wear gloves and safety glasses, keep children and pets away from the treated stump, and store the bag sealed in a cool, dry place away from fuels and other chemicals. Follow all directions on the package.

Tips for faster results

  • Fresh stumps take longer, while older, weathered stumps break down faster.
  • Keep the wood moist the whole time. Dry wood barely changes.
  • Reapply powder and water if the holes empty out.