Native to eastern North America, eastern Asia, and Europe, the ostrich fern is one of the most common native ferns, hardy in USDA Zones 3 through 7. The plants are hardy to -4 degrees Fahrenheit. Mass plantings do well naturalized in moist, shady woodland sites, wild gardens, rain gardens, and wet borders by streams or ponds. Though not ideal, they can also grow in containers. Offering attractive texture and form, they make good cut accents for bouquets. Ostrich ferns have no serious common pests and diseases and are resistant to rabbits and deer.
Light
This fern grows in part to full shade. Generally, open shade is best. Leaves may turn yellow and burn if exposed to full sun. Only if planted in an especially cool, moist location will it tolerate full sun.
Soil
Give the ostrich fern heavy clay soil that is humus-rich and moist. Maintain a neutral pH between 5 and 6.5. Native to marshes and creekbeds, they will tolerate some erosion and a lot of moisture.
Water
Water throughout the summer to maintain medium to wet conditions. Without enough moisture, the foliage may go dormant too early.
Fertilizer
While it is not necessary to fertilize an ostrich fern, if you are fertilizing other plants nearby, lightly fertilize the ferns, making sure not to overfertilize them as these plants are sensitive to fertilizer.
Ostrich Ferns vs. Cinnamon or Interrupted Ferns
There are two other types of ferns that look similar to the ostrich fern and are commonly mistaken for this plant. They are the Cinnamon Fern (Osmundastrum cinnamomea) and the Interrupted Fern (Osmunda claytoniana). The easiest way to tell is from the shape and look of the fronds on the plant. Simply turn one of the fronds over to examine it. The cinnamon fern has a furry or hairy spot near the sheath—where the stem and leaf meet—on the frond, and the interrupted fern sports forked veins and leaflets that are about 3 inches long and don’t extend down to the ground as the leaflets on the fronds of an ostrich fern do.
Pruning
Heavy pruning isn’t needed, but light trimming keeps ostrich ferns looking fresh. Clean up any old or awkwardly-shaped fronds. Prune dead foliage and fertile fronds in the late winter.
Propagating Ostrich Ferns
Ostrich ferns are aggressive spreaders. They’re bountiful, and can take over your garden, so since they spread by way of underground rhizomes, regular division each spring will keep them in their place. Here’s how:
Potting and Repotting Ostrich Ferns
If you plant an ostrich fern in a container, make sure that it is large enough to provide room for the fern to spread and grow as it matures. Plant it in rich, acidic clay soil and water regularly to keep the dirt moist. If keeping it indoors, provide it with the proper lighting. You will need to repot when the plant fills out the container and starts to become rootbound. These ferns do make a showy statement on outdoor patios and entryways when planted in a container.
Overwintering
Ostrich ferns are pretty hardy and can handle cold as low as -4 degrees Fahrenheit. Besides pruning any dead fronds in the fall when they go dormant, there’s not much more you need to do to overwinter these plants. New growth will pop back up in the spring.
Common Problems with Ostrich Fern
Ostrich fern is a relatively problem-free and deer-resistant plant. It can spread aggressively via rhizomes, so keep an eye on new plants popping up if you want to keep it within bounds.
