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Palace Theatre

Project type: 
Community Initiatives Green Funds

Fall 2006

ReForest London, the Old East Village Business Improvement Area, the City of London Parks Planning and Design Division, and Ron Koudys Landscape Architect partnered to install four trees at the Palace Theatre using “structural soil”. The trees were planted in a hand-dug pit approximately 20” deep that will be filled with a “structural soil” mixture of 80% crushed rock (3/4”) and 20% clay loam.

This planting technique is promoted by Ron Koudys Landscape Architects, who has provided technical design support. The method is one of the recommendations of a 2006 London Downtown Tree Management Report.

Why Structural Soil?

Soil Compaction

  • when roots encounter dense soil they change direction, stop growing, or adapt by growing abnormally close to the surface
  • this superficial rooting makes urban trees more vulnerable to drought and can cause sidewalk heaving
    macropores are the relatively large spaces between the soil aggregates


  • macropores are the relatively large spaces between the soil aggregates
  • provide aeration, water drainage, and rooting space
  • water drains quickly through macropores
  • air diffuses through macropores
  • roots navigate through macropores

Structural Soil

  • provides permanent macropore structure that will not compact
  • tree roots have the space to grow, to breathe, to find water, and to obtain nutrients