The fronds of a fern, or the leafy stems extending from the fern's trunk, can grow quickly and in just about any direction. Old growth tends to be deprived of nutrients and sunlight due to aggressive new growth. For this reason, pruning is necessary to maintain a healthy plant. The process for pruning ferns essentially consists of removing dead growth and pruning back for size.
Cut yellow or brown fronds at any point in the year. Usually, yellow or brown fronds occur because new growth shades old growth and causes it to die. Use a pair of pruning shears and cut the frond off at the base of the plant.
Look for leafless strands of fronds extending from the fern. If you locate any, cut them off at the base of the plant with the shears.
Trim the fern to maintain your desired shape during the spring or summer months. Ferns respond well to aggressive pruning and will grow back healthier and larger. Focus on shaping the sides of the fern and not the top of the fern. Cut back the leaves to a manageable length.
Remove undergrowth and dead leaves from around the trunk of the plant when you aggressively prune. This will allow air to flow through the stem system of the plant.