Ferns naturally propagate from spores, but the easiest way to acquire more of the plant is to divide its rhizomes, which are stemlike fingers that may hide under the soil like a bulb. Roots grow downward from the rhizome, and the fronds of the fern grow up. If the fern is healthy, it will need to be divided every few years to prevent overcrowding. Ferns in the garden require less frequent dividing because they typically have more room to spread. Indoor ferns can be divided anytime, but dig up outdoor ferns early in the spring before new leaves start to flourish.
Prepare a work surface by spreading newspapers or a plastic cloth on your table or counter if you are working with an indoor plant.
Remove the fern from its pot. Tap the sides and bottom of the pot to loosen the soil and roots, then turn it upside down while securely holding the base of the plant. Guide the fern from the pot without pulling directly on it or you may tear fronds from the plant. Remove garden ferns by carefully digging them up with a shovel.
Lay the plant on your work surface and cut it in half, or in smaller sections, with your knife. Cut between the fleshy roots and not through them.
Repot the divided sections. A soilless medium with 50 per cent peat moss is recommended for indoor ferns. Replant garden ferns as needed.
Water the fern lightly the day before you plan to divide it. Moisture will help the plant slip from the pot and may prevent excess stress on the root system for both house and garden ferns.