Friday, November 25, 2011

The Stately Royal Fern

Royal Fern (Osmunda regalis)
Who does not know
That those famed caves, on Arran's western shore,
Were King's Coves called, because they shelter gave
To Scotland's bravest King in hour of need
And when we see how richly they are fringed
With royal fern, might not we almost think
This stately fern delighted still to grow
'Midst scenes once honoured by so great a prince
 -David Landsborough, Arran: A Poem

Royal ferns (Osmunda regalis - pronounced os-MUN-duh re-GAY-liss) are so named because individuals can grow to be rather large. Some specimens have been recorded up to 5 feet tall and 5 feet across. You can't miss them in the garden. Sterile fronds sprout as slender croziers in spring, yellowish green in color and lightly tinged with terra-cotta. Mature fronds are bright green. The leaves are deciduous, turning pleasing yellow in fall before becoming brown. When back-lit by the sun, the yellow fronds are distinct and beautiful.

Many gardeners struggle with wet soils. Filling in the low spots is often considered to be remedy, but the water is simply redirected somewhere else sometimes causing another problem. I recommend leaving the wet areas alone and populating them with suitable plants. The royal fern is such a plant. Because they thrive in wet soil, royal ferns are ideal in rain gardens and bog gardens, beside streams and ponds. They'll even live in standing water. Tramping outdoors, they are often found in light shade, but royal ferns can certainly tolerate full sun.

Orchid growers are familiar with royal ferns, though they may not realize it, for the dried rhizomes of royal ferns have been used as potting medium for their epiphytes. Other materials are now more often used.

Widely distributed, royal ferns can be found growing in many parts of the world. It's no surprise, then, that they are hardy in a wide range of climate zones. In North America, these perennials are hardy from USDA hardiness zone 3 to 10.

Though they can become large, mature royal ferns can be as small as 24 inches tall and as wide. Much depends upon the moisture level.

Not much soil preparation is needed. Tilling wet soil would be a futile exercise, anyway. A soil sample should be taken to your nearest Cooperative Extension Service office for analysis. Follow the instructions. Recommended soil pH is 6.0 to 7.8.

Plant bare-root ferns in mid- to late spring or fall. Container-grown ferns may be planted any time of year. Space them 24 to 48 inches apart.

Very little to no maintenance is needed. Fertilizer should not be necessary. Brown fronds may be removed in winter. Soil moisture should be maintained.

Suitable companion plants may include red maple, pond cypress, dawn redwood, myrtle-leaf holly, inkberry holly, baccharis, coastal leucothoe, elephant ear, cinnamon fern, netted chain fern, yellow water iris, jewel weed, horsetail and acorus.

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