To propagate brunnera, the most common method is to divide established clumps in early spring or fall; carefully dig up the plant, separate it into smaller sections with healthy roots and shoots, and replant each division in a new location with similar soil conditions and shade levels. 

Key points about propagating brunnera:

Best time to divide: Early spring when new growth is just emerging, or early fall. 

Division method: Use a garden fork to lift the clump, then carefully split it apart with a sharp knife or spade, ensuring each section has roots and at least one growing point. 

Planting new divisions: Place the divided sections in their new homes at the same depth as the original plant and water thoroughly to establish them. 

Important considerations:

Soil conditions: Brunnera prefers moist, well-drained soil and partial to full shade. 

Spacing: When replanting divisions, space them appropriately to allow for future growth.