Elegant and exotic, if not prehistoric-looking as well, tree ferns grow nicely in mild regions high in humidity, and they rarely endure frosts. Two types of tree ferns, Cyathea and Dicksonia, predominate the use in gardens and greenhouses around the world. These ferns with tall, upright stems carry a circular whorl of fronds from the plant's only growing tip. As with other healthy plants with few leaves, use restraint when pruning.
Inspect the tree fern to determine exactly what needs pruning. Look for dead, diseased or yellowing fronds and note if any fronds are partially broken.
Wear eye protection, long sleeves and gloves before working around the trunk and fronds of the tree fern as numerous skin-irritating hairs and scales line the fronds and stem trunk.
Remove all dead fronds by making a crisp, one motion cut of the hand pruner blades 2 to 4 inches above where the frond stem attaches to the crown of the growing tip. Take care to not accidentally cut or damage any emerging, unrolling frond stems in this area. Allow the frond to drop after cutting or grasp the frond with your free hand and pull it away from the crown. Reach higher fronds with an extension pole or ladder.
Prune away any diseased fronds, such as those that are rotting or heavily infested with pests such as mealybugs or spidermites. Make pruning cuts 2 to 4 inches above the base connection to the growing crown at the top of the tree fern stem.
Step back and re-examine the tree fern. Look to see if the fronds are evenly and attractively distributed around the entire growing tip. Avoid lop-sided, over-pruning of the crown.
Consider partial removal of fronds that have broken regions or are partially diseased or yellowing. Clip off the frond stem that removes substantial diseased, yellowed or tattered areas, particularly in the fall.
Wait until spring to prune when there is no further threat of frosts if the fronds are damaged or killed from winter frosts.