The Ostrich Fern is a popular perennial plant prized for its elegant, vase-shaped foliage. It is widely recognized for its edible, tightly coiled young fronds, known as fiddleheads, which are a springtime delicacy. Despite its beauty and utility, the Ostrich Fern is a vigorous spreader that can rapidly colonize a garden space, creating dense, lush colonies.
Understanding Rhizomatous Growth
The rapid, aggressive spread of the Ostrich Fern is due to its rhizomatous growth habit, which involves specialized underground stems called runners. These runners are modified horizontal stems that grow out from the main plant crown, allowing the fern to propagate vegetatively and form new individual plants. A single mature fern can generate multiple runners in a growing season, each capable of establishing a new satellite clump.
These dense underground runners extend in all directions, quickly creating a colony that can spread several feet outward from the original planting. This vegetative method is far more effective and faster for colonization than spore-based reproduction. While the Ostrich Fern does produce spores, this is a slower, less reliable method for establishing a new colony. The speed of the rhizomes is why the plant is often described as an aggressive groundcover that can overtake nearby plants.
Controlling Unwanted Expansion
Managing the expansion of the Ostrich Fern requires a proactive approach focused on interrupting the rhizomes before they establish new crowns. A primary method is the installation of a physical root barrier around the perimeter of the desired growing area. These barriers, made of thick plastic edging or pond liner, must be buried at least six to eight inches deep to effectively block the horizontal runners.
Manual Control Methods
Regular hands-on maintenance is also necessary to control spread. This is best performed in the early spring just as new growth emerges or in the late fall.
- Division of the plant: Dig up the entire fern and use a sharp spade or knife to separate sections of the rhizome with attached roots and fronds.
- Manual removal: Consistently remove new satellite plants, which appear as small crowns emerging from the runners.
- Severing runners: Chop the connecting runners with a sharp shovel or hoe at the perimeter of the planting area to halt expansion.
Environmental Factors Affecting Spreading
The rate and density of Ostrich Fern spreading are directly influenced by the suitability of the growing environment. The fern is native to marshy areas and creekbeds, meaning that moist, humus-rich soil provides the ideal conditions for rapid rhizome development and colonization. Soil that is consistently damp and rich in organic matter allows the runners to grow quickly and establish new plants in dense clusters.
Conversely, conditions that deviate from this ideal environment will naturally slow or stunt the spreading process. Ostrich Ferns planted in dry soil or those exposed to full sun will exhibit less aggressive growth. In hot, dry conditions, the fern’s fronds may brown or wilt, and the plant will prioritize survival over extending its network of underground runners.