To propagate Three Way Sedge (also known as “Dulichium arundinaceum”), the most common method is division, which is best done in early spring by carefully separating a clump of the plant into smaller sections, ensuring each section has roots attached, and then replanting them in moist soil; you can also try propagating it from seeds, though germination may be inconsistent. 

Key points about propagating Three Way Sedge:

Division is preferred: Most gardeners recommend dividing established plants as the easiest way to propagate sedges, including Three Way Sedge. 

Timing: Early spring is the ideal time to divide the plant. 

Process: Dig up a clump of the plant. 

Carefully separate the clump into smaller sections with roots attached.  Replant the divided sections in moist soil. 

Other points to consider:

Seed propagation: While possible, seed germination can be erratic, so division is usually the more reliable method. 

Planting location: Three Way Sedge thrives in moist soil and can be planted in areas with partial shade. 

Check local regulations: Before planting Three Way Sedge, ensure it is not considered invasive in your region.