Effectiveness

• Horseradish prevents insect infestation by repelling bugs. It also is believed to have antimicrobial properties, preventing plant problems caused by bacteria and fungi.
  
  

Correct Use

• Since horseradish repels rather than kills insects, neighboring plants still are vulnerable to insect infestation if not sprayed. Horseradish must be applied to all plants in an area to prevent infestation. It must be re-applied weekly and after rainfall.
  
  

Use as a Spray

• Make a spray by boiling the horseradish root in water, strain it, and then combine with an unscented soap to facilitate adherence to plant leaves.
  
  

Companion Planting

• The insect repellent and disease prevention benefits of the root also can be achieved by utilizing it as a companion planting.
  
  

Considerations

• To plant horseradish alongside vulnerable plants, make sure the plant's requirements are compatible with those of horseradish. Horseradish requires full sun to partial shade with well-drained soil. It can grow alongside plants that require similar environments.