Osmunda spectabilis
American royal fern
Overview
Osmunda spectabilis is a large, deciduous fern growing 2-5 feet (60-150 cm) tall, occasionally to 6 feet (180 cm) in wet sites, forming clumps from a stout, slowly creeping rootstock. The bright green fronds are twice-divided into widely spaced, oblong leaflets, giving an open, almost locust-leaf appearance unlike the lacy texture of many ferns. In spring, fertile fronds carry clusters of brown, bead-like spore cases at their tips, resembling a flower spike, which gives the group the name flowering fern. The spores ripen and are shed by early summer, after which the fertile tips wither. Native to eastern North America, O. spectabilis grows in swamps, bogs, wet woodland, stream banks, and the margins of ponds, in acidic, constantly moist to wet soil. It needs reliable moisture and declines in dry ground, but tolerates standing water and full sun where its roots stay wet. The fronds turn yellow to bronze in autumn before dying back, and the plant is long-lived once established. It is hardy to USDA zone 3.
Native Range
Native to eastern North America, from Newfoundland and Ontario south to Florida and Texas. Grows in swamps, bogs, wet woods, and along streams and ponds in acidic, moist to wet soil.Suggested Uses
Grown in bog gardens, rain gardens, pond and stream margins, and damp woodland plantings. Spaced 24-36 inches (60-90 cm) apart, it forms a tall clump in consistently wet ground where few other ferns grow.How to Identify
Appearance
Size & Dimensions
Height2' - 5'
Width/Spread2' - 3'
Reaches mature size in approximately 4 years
Bloom Information
As a fern, the species bears no flowers. Fertile fronds tipped with brown spore-bearing structures appear in spring, ripen, and release spores by early summer. The spent fertile tips then wither while the green sterile fronds continue through the season.
Detailed Descriptions
Foliage Description
Bright greenGrowing Conditions
Sun Requirements
Requires 3-8 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Osmunda spectabilis grows in partial shade to full sun in constantly moist to wet, acidic, humus-rich soil across a pH of 4.5 to 6.5. Reliable moisture is the main requirement; it tolerates boggy ground and standing water but declines and scorches in dry soil. The fern is hardy to USDA zone 3 and dies back to the rootstock each winter. It is slow to establish and spreads gradually, and recovers slowly from disturbance once settled. It has few pests. A mulch of leaf litter helps keep the roots cool and moist.Pruning
No routine pruning is needed. Dead fronds can be cut back in late autumn or left until spring to protect the crown. Removing yellowed fertile fronds after the spores shed tidies the clump.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
fall
Container Growing
✓ Suitable for container growing
Minimum container size: 5 gallons