Japanese painted ferns can be propagated by division or by growing from spores

Division

  1. Prepare the soil: Loosen the soil around the fern with water. 
  2. Dig up the fern: Carefully dig around the fern and lift the root ball out of the soil. 
  3. Separate the root ball: Use sharp gardening shears to divide the root ball into sections. Each section should have a few fronds and a good amount of roots. 
  4. Replant the sections: Plant each section in a new location at the same depth. You can plant them in pots or in the ground. 
  5. Water: Water the sections thoroughly to settle the soil. 
  6. Provide shade: For the first few weeks, provide partial shade to help the ferns establish. 

Spores

  1. Collect spores: Cut a frond and place it spore-side down on a sheet of waxed paper. 
  2. Prepare the potting mix: Heat some slightly moist potting mix in a microwave until it steams. 
  3. Plant the spores: Put the potting mix in a container and sprinkle the spores on top. 
  4. Provide moisture: Keep the potting mix moist. 
  5. Wait for new growth: Small green plants should appear in a month or two. 

You can also propagate Japanese painted ferns by tissue culture, but this requires sterile conditions.