Collectors Issue 2005
Tips on growing North Country ferns
by Nick Woodin
As I left my teenage years behind, my mother and I seemed to agree on less and less, but we always had a connection in gardening. One thing she often mentioned from her childhood in Keene Valley was a small fern that grew in the cracks of a large rock on which the camp below her mother’s was built. Bluebells, miniaturized goldenrods and mosses also took root in these shallow clefts, watered by rain that washed down off the rock.
The fern was a Woodsia. Rusty woodsia (Woodsia ilvensis) grows in clumps sometimes four inches high, with fronds six to eight inches long. Some years after I moved to the Adirondacks, I brought a clump of that fern to my own garden and planted it in a gap between two rocks on a dryish slope, in partial shade. Over three or four years I watched it slowly die away. Later I found whole slopes of the same fern on the rocky mountainsides near where I live, in Jay. Since then, I have planted some around a rock on a damp but sunny bank at the edge of my garden; there they survive with no difficulty but do not get larger.
Light and drainage are the key to successful cultivation of ferns. Sensitive ferns (Onoclea sensibilis), which grow in sunny or shady moist areas, are a weed in the more protected, wet parts of my garden. The graceful fronds of maidenhair fern (Adiantum pedatum) prefer lightly shaded woods. It is not common here, but where you find it you often find a lot of it. Maidenhair moves easily, is divisible and will grow well in an average garden soil. (Maidenhair is one of the few ferns whose clumps you can divide. Japanese painted fern, a nonnative, is another; any of the ferns with creeping rootstocks, such as the polypodys that grow on top of rocks, are separable.) Maidenhair will survive in full sun; I have an eighteen-inch-tall bunch planted in the open, over a septic tank at the foot of my front steps. The plant doubles in size every year, and I take divisions off it to use elsewhere in the garden. During hot, dry weather in July and August its leaves will get a little crispy (more rarely, they burn off completely). Then I water it, which doesn’t help the leaves at that point but keeps the plant alive for another year. For several years I watched a clump of maidenhair survive near a headstone in a Keene cemetery where thyme outcompetes grass in the baking sand, and a friend had a magnificent line of them beside her east-facing kitchen door. They stood in full sun for half the day and were never watered.
Interrupted ferns (Osmunda claytoniana) make a stately front entrance. They grow in a vaselike shape up to four feet tall and slowly form larger and larger clumps. Eventually they produce offshoots. In full sun they are often defoliated by a small green worm about the time of the summer solstice (probably the same worm—I think it’s the larvae of a fly—that defoliates the columbine). Pyrethrum or hand-picking will take care of the worms, which will not kill the ferns but will leave them looking raggedy.
Ostrich fern (Matteuccia struthiopteris) is another tall, vase-shaped plant. It grows best in cool, wet, rich humus. Like bracken and several of the woodland ferns, ostrich ferns spread by underground rhizomes and may end up some distance from where you planted them (the spreading takes time and can be controlled, however). Lady fern (Athyrium filix-femina), one of the archetypal lacy ferns of woodsy driveways and shaded country roads, forms large groups quite quickly. It moves easily and the clumps are somewhat asymmetrical.
Ferns, meadow rue and monkshood, with perhaps an understory of wildflowers, make an alternative to hostas for a garden bed on the shady side of the house. And unlike hostas, ferns don’t attract deer. Popular ferns such as maidenhair can be found in many local nurseries or in mail-order catalogs.
Ferns reproduce by spores in the wild, but it’s difficult to propagate them by this method. A simpler approach is to transplant them from the woods. Ferns that will work in the garden grow in damp, deciduous woodlands, along forest roads or on riverbanks. Get permission to dig up ferns from private property; it is illegal to remove any plant from Forest Preserve. (Some species are endangered in New York State and should never be moved. These include blunt-lobe grape fern [Botrychium oneidense], found in Essex County; rugulose grape fern [Botrychium rugulosum], found in Essex, Hamilton, St. Lawrence and Herkimer Counties; fragrant cliff fern [Dryopteris fragrans], found in Essex, Franklin and Hamilton Counties; alpine cliff fern [Woodsia alpina], found in Essex County; smooth cliff fern [Woodsia glabella], found in Essex, Hamilton and Herkimer Counties; climbing fern [Lygodium palmatum], found in Saratoga and Oneida Counties; and Braun’s holly fern [Polystichum braunii], found throughout the Adirondacks.)
When moving ferns from the forest, take small ones, use a shovel and dig around the plant to get the rootstock (you may have to sever connections to nearby ferns with species that spread by rhizomes); some ferns must be more or less scraped off rocks with a shovel. Replant them as soon as possible in situations of shade and dampness similar to those in which they grew. Early September is a good time to do this, after growth is over but before the fronds have disappeared; thus the ferns are still identifiable. You can also transplant them in early spring after the fronds have opened. Moving ferns in the summer will work if you plant them immediately and water them well. They may not look good that year but should survive.
Most ferns do better in light shade than in full sun; rusty woodsia is an exception, as are bracken (Pteridium aquilinum) and hay-scented fern (Dennstaedtia punctilobula), an occupant of neglected fields. Ferns tend to like damper soils, but shade helps compensate for a lack of moisture. Some fern habits are mysterious; for instance, polypodys grow on the tops of lightly shaded rocks. Christmas fern (Polystichum acrostichoides), a hardy evergreen variety, has a penchant for rocky slopes. A bed of Christmas ferns may need rocks both in the soil and on the surface.
Ferning for You
The Hamilton County Soil and Water Conservation District sells a variety pack of rooted cuttings of native Christmas, cinnamon, maidenhair, New York and ostrich ferns. The ordering deadline is the end of March. Plants arrive in late April and are picked up at the district office in the Old Lake Pleasant Fire Hall. Call (518) 548-3991 for more information, or see www.hamiltoncountyswcd.com.