Landscape Plants of the Upper Midwest

Kalm St. Johnswort

{Picture of Kalm St. Johnswort}

Plant Information

  • Plant Type: Shrub: Small
  • Scientific Name: Hypericum kalmianum Play audio of plant name
  • Family: St. Johnswort
  • Zone: 4
  • Plant Size: 2-3'
  • Bloom Time: Summer
  • Bloom Color: Yellow
  • Habit: Mounded: spreading
  • Culture:

    Adaptable. Tolerates poor dry soils. Full sun.

  • Notes:

    Has yellow flowers that are present from July into September and red-brown exfoliating bark. A good plant for difficult sites. Does not respond well to renewal pruning.

  • Pruning:Pruning animation

    Heading back is done to shape and reduce the size of the plant. Cut prominent shoots back inside the body of the plant to where they meet another branch.

    Heading back may be done from late fall to mid-July.

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Landscape Plants of the Upper Midwest

Bill Hoch, Associate Professor
Montana State University

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