This can sometimes be tricky, as the root structure inside the pot may be dense and unwieldy. Next, as much soil as possible must be removed to allow access to the root ball.
Using a sharp, long bladed knife to cut the root ball into equal pieces, depending on the number of plants desired. Each part should then be replanted into a separate container.
Dividing ferns is unlike dividing other perennials in that ferns can take quite a bit of abuse when dividing.
The root ball is usually extremely tight, so it may take considerable force to cut when dividing ferns.
Many other perennials are more delicate and should be handled slightly differently than when dividing ferns.
More information about dividing ferns can be found from several locations. Internet sites focusing on gardens and landscaping will likely have information about dividing ferns.
There will be books in a local library about growing ferns, and dividing ferns is a big part of growing them. Ask a garden specialist for any other information needed when it comes to dividing ferns.