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Royal Fern
Osmunda regalis
Royal Fern is grown for its foliage rather than flowers, giving the garden structure and color all season long.
Months here are Northern Hemisphere months; in the Southern Hemisphere, shift them by six months.
Growing Royal Fern
Plant it in part shade. It prefers high water. It is hardy in USDA zones 3–9. Expect it to reach about 4 ft tall and 3.5 ft wide at maturity, in roughly 3 years (not yet checked).
What was checked
Mature height and spread, hardiness zones, sun and the trait tags were checked against named botanical sources for this plant. The bloom months and water need on this page were not, and each fact above says which. The planting, spacing and size sections are derived from these checked facts by a fixed rule, not checked separately, and the plant type is the library's own classification.
When to plant Royal Fern
Plant Royal Fern in early spring as soon as the soil is workable, or in early fall at least six weeks before your first frost, so roots establish in cool weather. In zone 6, the middle of its hardy zones 3 to 9, spring means March to May and fall means August or September.
Month-by-month timing for your zone is on the planting calendar; if you garden near zone 6, the middle of this plant's hardy range, start with zone 6 in March. Derived from the plant's category, zones and bloom months plus typical zone frost dates, not checked separately.
How big does Royal Fern get?
4 fttall5 ft 7 inan adult3.5 ftwideSee Royal Fern in a garden plan: the planner shows it in 3D beside everything else you add, growing toward this size over the years.
How far apart to plant Royal Fern
Derived from the mature spread above by a fixed rule, not checked separately: spacing is the spread, center to center.
Space Royal Fern about 3.5 ft apart, center to center, so each plant has room to reach its full width.
Add Royal Fern to a garden plan and the planner draws it at its full width, so you see the spacing before you buy.
Where these facts come from
Royal Fern's height, spread, hardiness zones, sun and trait tags were checked against 5 published sources on July 29, 2026. Each one is linked below with every fact it carried, which can include a fact this page still marks as not yet checked, because a source carrying a value is not the same as the value being held to the standard. Facts not in that list, and the planting, spacing and size sections, are not covered by these sources.
- Missouri Botanical GardenPlant Finderheight, spread, hardiness zones, sun and trait tags
- NC State ExtensionGardener Plant Toolboxheight, spread, hardiness zones, sun and trait tags
- Chicago Botanic GardenPlant Finderheight, hardiness zones and sun
- Lady Bird Johnson Wildflower Centerheight, sun and trait tags
- RHSRoyal Horticultural Societyheight, spread and sun
How the checking works, and what each standard covers, is on the verified plants page.
Good to know about Royal Fern
Curated from university extensions, botanic gardens and other primary sources, with the source named on every note. A note reports what its source says; where that differs from a fact above, the fact above is this entry's stored value, and its mark says whether it has been checked.
Safety
Do not eat the fiddleheads. Osmunda croziers are at least mildly toxic and can cause nausea, dizziness and headache; ostrich fern is the fern to forage instead. per Miller Library
Worth knowing
It never flowers. The name 'flowering fern' comes from the rusty, tassel-like fertile clusters at the frond tips: these are spore-bearing structures, not blooms. per NC State
Mature size tracks moisture
Sources disagree on height, but moisture is the driver: about 0.6 to 0.9 m in an average moist garden, up to 1.5 to 1.8 m where the ground stays wet. per NC State and Missouri Botanical Garden
Safe around cats and dogs
It is not on the ASPCA toxic lists for cats or dogs, and NC State assigns it no poison rating; regarded as non-toxic to pets. per ASPCA and NC State
Thrives in wet ground
An obligate-wetland fern that even takes short spells of standing water: superb at pond and stream edges, in bogs, water gardens and rain gardens. per NC State and Go Botany
A clumper, not a runner
It forms a large clump on a stout crown and expands slowly; it will not colonize the bed like the running ostrich fern. Divide the crown to propagate. per NC State
Pest-free and deer-resistant
No serious insect or disease problems, and seldom damaged by deer: a low-input plant once sited in the moist shade it wants. per NC State
What pairs well with Royal Fern
Good companions share its growing conditions and add something it lacks: an earlier or later bloom, a lower carpet in front, or structure through winter.
Christmas Fern
Takes part shade to full shade and moderate to high water; evergreen, so the bed keeps its shape through winter; lower at 1.5 ft, for the front of the border; both are North American natives.
Eastern Hemlock
Shares part shade and moderate to high water; evergreen, so the bed keeps its shape through winter; both are North American natives.
Bergenia
Takes part sun to part shade and moderate to high water; evergreen, so the bed keeps its shape through winter; lower at 1.5 ft, for the front of the border.
Wild Ginger
Takes part shade to full shade and moderate to high water; low at 6 in, to carpet the ground beneath; both are North American natives.
Autumn Fern
Shares part shade and moderate to high water; evergreen, so the bed keeps its shape through winter; lower at 1.5 ft, for the front of the border.
Holly Fern
Takes part shade to full shade and moderate to high water; evergreen, so the bed keeps its shape through winter; lower at 1.5 ft, for the front of the border.
Japanese Forest Grass
Shares part shade and moderate to high water; its seed heads stand through winter, for structure and the birds; lower at 1.5 ft, for the front of the border.
Hellebore
Shares part shade and moderate to high water; evergreen, so the bed keeps its shape through winter; lower at 1.5 ft, for the front of the border.
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Drop this plant onto a 3D plan, see how it fills in, and watch your whole garden bloom across the year.