What hardiness zones is Osmunda regalis suitable for?

Osmunda regalis is suitable for USDA hardiness zones 3, 4, 5, 6, 7, 8, 9.

What are the sun requirements for Osmunda regalis?

Osmunda regalis requires Part Shade.

How much water does Osmunda regalis need?

Osmunda regalis has High water needs.

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Ferns

Osmunda regalis

Royal Fern

Osmundaceae

Eastern North America, Europe, Asia, Africa, Central and South America

At a Glance

TypeFern

HabitClumping

FoliageDeciduous

Height2-6 feet (60-180 cm)

Width2-4 feet (60-120 cm)

Maturity5 years

Growing Zones

USDA Hardiness Zones

3 - 9

Zone 3

Zone 4

Zone 5

Zone 6

Zone 7

Zone 8

Zone 9

These zones indicate the coldest temperatures this plant can typically survive.

Frost Tolerancehardy

Key Features

Deer Resistant

Native to North America

Maintenancelow

Overview

A large, deciduous fern forming a vase-shaped clump 2-6 feet (60-180 cm) tall and 2-4 feet (60-120 cm) wide, with some specimens in optimal conditions reaching 6 feet (180 cm) or more in height. Fronds are bipinnate, 2-5 feet (60-150 cm) long, with oblong, smooth-margined pinnules 0.5-1.5 inches (1.5-4 cm) long and 0.3-0.7 inches (8-18 mm) wide. Fronds emerge pale green with pinkish-bronze coloring in spring, maturing to bright green through summer. In autumn, foliage turns yellow-gold to russet before dying back. Fertile fronds terminate in clusters of tightly packed, spore-bearing pinnules that turn from green to rusty brown as spores ripen, giving a flower-like appearance from a distance and accounting for the common name Flowering Fern. These fertile segments appear at frond tips or on separate upright fronds, typically in late spring to summer. The plant grows from a large, fibrous rhizome base that accumulates over decades. Growth rate is moderate to slow; established clumps expand outward 2-4 inches (5-10 cm) per year.

Native Range

Native across a wide range spanning Europe, Asia, Africa, and the Americas, including eastern North America from Newfoundland south to Florida and west to the Mississippi River, as well as Central and South America. Found in wet meadows, marshes, stream banks, and woodland swamps in acidic, permanently moist soils. In Europe, it occurs from the British Isles east through temperate zones to the Caucasus.

Suggested Uses

Planted at pond edges, bog gardens, stream banks, and wet woodland gardens at 3-4 foot (90-120 cm) spacing. Suitable for rain gardens in zones 3-9 where soil remains moist. Not suited to dry borders or sites with seasonal drought; established plants decline and die if moisture becomes insufficient for more than 2-3 weeks.

How to Identify

Fronds are bipinnate, 2-5 feet (60-150 cm) long, with smooth, oblong pinnules. Fertile pinnules at the frond tip are clustered and heavily covered in brown sporangia, turning distinctly rusty-brown when spores are mature, in contrast to the sterile green pinnules below. The large, vase-shaped growth habit and preference for persistently wet conditions distinguish it from other garden ferns. The prominent fibrous rhizome crown exposed above the soil surface on older plants is also characteristic.

Appearance

Size & Dimensions

Height2' - 6'

Width/Spread2' - 4'

Reaches mature size in approximately 5 years

Colors

Foliage Colors

green

bronze

Fall Foliage Colors

yellow

gold

russet

Bloom Information

Osmunda regalis does not flower. Fertile fronds bearing sporangia appear from late spring through summer, typically May to August in zones 3-7. The rusty-brown fertile pinnule clusters are visible for 6-10 weeks before spore dispersal is complete. Spring frond emergence, with its pinkish-bronze coloring, is the primary ornamental display period.

Detailed Descriptions

Foliage Description

Pinkish-bronze emerging, bright green in summer, yellow-gold to russet in autumn

Growing Conditions

Sun Requirements

Full Sun

Partial Shade

Full Shade

Requires 2-8 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

Soil Requirements

pH Range4.5 - 6.5(Acidic)

357912

Soil Types

peatloam

Drainage

wet

Water & Climate

Water Needs

High

Frost Tolerance

hardy

Time to Maturity

3-5 years

Care & Maintenance

Care Guide

Plant in consistently moist to wet, acidic soil with a pH of 4.5-6.5 in partial shade to full sun. Full sun is tolerated where soil remains consistently moist; fronds scorch and brown at the tips when the soil dries even briefly during summer. Standing water at the crown is tolerated; the plant grows naturally at the edge of standing water bodies. Mulch 3-4 inches (8-10 cm) deep to maintain moisture. No fertilization is needed in organically rich, naturally wet soils; in average garden conditions, apply a slow-release, balanced fertilizer in early spring. Division is rarely needed but can be done in early spring; clumps are large and difficult to divide due to the woody rhizome mass. Established clumps are long-lived; individual crowns persist for decades.

Pruning

Cut dead fronds to the ground in late fall after the first frost, or leave them in place through winter as they collapse naturally and decompose slowly. Remove old brown fronds in early spring before new growth emerges. No summer pruning is needed; removing green fronds during the growing season reduces photosynthetic capacity and weakens the plant.

Pruning Schedule

early spring

Maintenance Level

low

⚠️ Toxicity Warning

Non-toxic