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Assessing your soil’s drainage

Bergenia 'Eden's Dark Margin' adapts well to poor drainage conditions
Photo: Jardin botanique de Montréal (Gilles Murray)

Soil structure refers to the way in which the sand, silt and clay particles are arranged relative to each other.

Here is a simple drainage test:

  • dig a hole 30 to 60 cm deep, fill it with water and allow it drain;
  • refill it with water, then time how long it takes to drain completely;
  • if the hole takes 3 to 4 hours to drain, you have good drainage. If it takes 5 to 12 hours to drain, you have moderate drainage. If there is any water left in the hole after 12 hours, you have poor drainage.

Solutions to drainage problems

  • Choose plants suited to your growing conditions. Examples:
    • Trees and shrubs: European black alder (Alnus glutinosa), swamp oak (Quercus palustris), redtwig dogwood (Cornus alba), false indigo (Amorpha fruticosa), hackberry (Celtis occidentalis), weeping willow (Salix alba 'Tristis'), creeping willow (Salix repens), etc.
    • Perennials: bergenia (Bergenia sp.), goatsbeard (Aruncus sp.), turtlehead (Chelone sp.), darmera (Darmera peltata), Siberian iris (Iris sibirica), ligularia (Ligularia sp.), butterbur (Petasites sp.), rodgersia (Rodgersia sp.), globeflower (Trollius sp.), etc.
  • Improve the soil structure.
  • Build raised beds.

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