Asparagus fern, known botanically as Asparagus densiflorus Sprengeri, is an evergreen perennial plant that belongs to the lily family and is not actually a fern. Its long, round, thick and tapered fronds grow from a basal clump that propagates itself vegetatively by developing young plants along the perimeter of the clump. According to Texas A&M University, the plants can cope with fairly harsh handling to divide the clumps entirely or remove the perimeter bulblets for transplanting or simply to control the size of the parent plant.
Remove the plant from its growing container or excavate a few inches of soil around the bulblets for ground planted ferns. This will expose where the bulblet meets the parent clump.
Break off the small undesired bulblets from the parent plant with your hands, by snapping and pulling down and then out away from the plant.
Excise large bulblets or those attached to a very large clump with a garden knife with a long and sharp blade. Run the blade between the offset plant and the parent clump cutting cleanly through the tissues. Taking a bit of the parent clump along with the offset will not harm the parent plant.
Replant the parent asparagus fern immediately, firming the soil around the cut sites and watering the surrounding soil in well to keep it evenly moist. Do not allow the soil around the excision sites to dry out for several weeks after the separation. Plant the bulblets into soil and water or simply discard them.