Fern plants have root structures known as rhizomes, which are reproductive plant parts consisting of a horizontal stem that has shoots growing up and roots on the underside. Although ferns are attractive indoor or hanging plants, they eventually become root bound and outgrow their container. When this happens, the plant must be separated or repotted in a larger container. If this is not done soon enough, the original pot may have to be broken or cut in two if it's made of plastic. However, with careful handling, this can be done without harming the fern.
Remove the plant from its pot carefully. Gently shake off excess potting soil and lay the fern on its side.
Divide the root ball gently by hand as far as possible without tearing the roots or the upper foliage. Cut through the desired dividing line with a razor knife fitted with a new blade to minimise damage to the roots.
Separate the upper fronds as gently as possible without ripping them apart. Be patient -- this process might take some time before you have two healthy separate plants.
Add about an inch of perlite pellets to the bottom of two suitably large pots to promote drainage. Place each plant in its pot and pack a rich blend of potting soil around their root structures, but do not use ordinary topsoil from the garden. Both perlite and potting soil are available from reputable nurseries or gardening outlets.
Tamp the soil down and give each plant a good watering. Hang the pots, or place them in a brightly lit area away from direct sunlight before misting the foliage with a spray bottle.
Add indoor plant food two to three weeks after repotting. This will allow enough time for the severed roots to heal without being burnt by fertilisers.
Water regularly, without allowing the soil to become soggy. Do not let the potting soil dry out completely while the ferns are becoming established. Mist the foliage daily during hot weather.
Do not use scissors or pruning shears to separate the root ball; this will bruise the roots and the fern may not survive the repotting process.