Sword fern is all-around favorite

Last Updated: 
January 11, 2010

fern photo by Linda McMahan

CORVALLIS, Ore.—If you were allowed to grow only one plant in the entire world (other than for food), what would you choose? OSU Extension horticulturist Linda McMahan doesn't hesitate to claim that for gardeners the first choice could be the Western sword fern, known botanically as Polystichum munitum.

The reasons are many, McMahan points out. First, they're "tough." They can grow in poor or rich soil—it doesn't matter, she said, and although they prefer shade, they can grow in full sun. Once established, they are drought resistant and usually don't need to be watered.

"One of the finest features of the sword fern is its fibrous root system," McMahan said. When planted on a slope, its spreading roots stabilize the bank and prevent erosion. The ferns can grow three-to-five feet tall and act as an excellent ground cover.

In the spring, new fronds of this beautiful perennial evergreen start tightly coiled and then uncurl as they stretch out in long fingers. Shade from the dense foliage helps control weeds. Old foliage is retained over the winter and can be trimmed back each spring to keep the fern smaller.

"If you leave the old foliage, however, you'll provide habitat for salamanders and other beneficial creatures," McMahan said.

In the wild, sword ferns grow next to streams but also rock outcroppings. Their name comes from the divisions on the end of each leaf that look like tiny swords. On the backside of the leaves, spores that appear to be brown spots are clustered together in groups. Sword fern spores can travel long distances on wind currents, and when they reach suitable habitats, reproduce more sword fern plants.

"The ferns grow wild and well in western Oregon and also can live in gardens on the east side of the Cascades," McMahan said, "but they may need additional water to thrive in eastern Oregon."

The giant chain fern, Woodwardia fimbriata, native to the southwestern quarter of Oregon, is another option for Oregon gardeners. "It's in Zone 8, which means it can grow only in western valleys or on the coast," McMahan said. "The giant chain fern requires watering, so it's not as tough as the sword fern, but can grow up to 6 to 8 feet, and its large stature makes it a desirable native accent plant in a shady garden."

Author: Judy Scott
Source: Linda McMahan