To propagate an Interrupted Fern (Osmunda claytoniana), the most common method is division by rhizome cuttings – simply take a section of the underground rhizome with at least one frond attached, plant it horizontally in a moist, well-draining medium, and keep it humid until new growth appears; you can also try propagating it from spores, though this method is more complex and takes longer. 

Key points about propagating Interrupted Fern:

Best time to divide: Early spring when new growth is just emerging. 

How to take a rhizome cutting: Carefully dig around the established plant to expose the rhizomes. Use a sharp knife to cut a section of the rhizome with at least one healthy frond attached.  Ensure each cutting has a few roots. 

Planting the cutting: Prepare a pot with a well-draining potting mix, like a mix of peat moss and perlite. Plant the rhizome cutting horizontally just below the soil surface.  Firmly press the soil around the cutting and water thoroughly. 

Care after planting: Place the pot in a shaded area with high humidity. 

Keep the soil moist but not soggy.  Monitor for new frond development. 

Propagating from spores (more advanced): 

Collect spores: Gather mature fronds with visible spore clusters (sori) on the underside. 

Prepare the medium: Use a sterile, fine-grained potting mix or a specialized fern spore-growing mix. 

Sow spores: Gently sprinkle the spores onto the surface of the prepared medium. 

Create a humid environment: Cover the container with plastic wrap or a glass lid to maintain high humidity. 

Light conditions: Place the container in bright, indirect light. 

Important considerations:

Check local regulations: In some regions, collecting Interrupted Fern from the wild may be restricted. 

Choose healthy plants: Select a vigorous, well-established plant for division. 

Sterilize tools: To prevent disease spread, always sanitize your cutting tools before propagating.