There are many interesting kinds of ferns in the Ottawa area and this article will showcase some of them. Let’s first look at where they can be found. Some ferns typically like forest settings that are moist, shady, and with sufficiently rich soil. These include Christmas Fern, Spinulose Wood Fern, Northern Lady Fern, Ostrich Fern, Oak Fern, and Maidenhair Fern. Ferns can also be specialized to certain habitats such as limestone outcrops or other well drained areas. In these typically calcium rich soils and rocky cliffs you can find Marginal Wood Fern and Common Polypody Fern. Then there are the ferns often associated with freshwater wetlands or swampy areas who like their feet wet as much as possible. These include Sensitive fern, the large and showy Cinnamon and Royal ferns, and Interrupted Fern. There are about 36 species of ferns in the Ottawa District in 3 fern families. Some are common and widespread, including Ostrich Fern, Northern Lady Fern, and Sensitive Fern but many others are difficult to find or of low dispersal. This article will introduce some of the beautiful local ferns and talk about what they require to grow in a garden setting.
Some of our native ferns may be suitable for woodland gardens but I have to say that with a word of caution. Some ferns were once so popular that it nearly led to their demise so we must remain vigilant in our conservation efforts. This included the Ostrich fern, Shield ferns, Royal ferns, Woodsias, and Spleenworts, among others. In addition, early last century ferns were being systematically harvested on a huge scale for use in floral arrangements. In 1914 the New York Times reported that 60 million wild ferns were imported to New Your City alone to supply the florist trade. In that era ferns became less common and, with a developing conservation ethic, industries were forced to develop ways to propagate desirable ferns.
Today the largest threat to ferns is the destruction of their habitats. It would be a shame to see ferns disappear as, looking back in time, fossil evidence indicates that ferns and related non-flowering vascular plants once dominated the landscape at least as far back as the Devonian Period, 360 million years ago. Today’s ferns are not precisely the same species that were present back then but the Cinnamon Fern, Royal Fern and Interrupted Fern persist from when dinosaurs roamed the land during the Cretaceous Period, 180 million years ago. During the conditions that caused the extinction of the dinosaurs many ferns also followed suit so the species that exist today are typically well adapted to growing in low light settings.
Life Cycle of Ferns: Ferns are in a group of vascular plants that reproduce by spores, not seeds. If you look underneath some fronds in mid-summer you will see greenish to tan-coloured dots near the edge of the pinnae, or “fingers” of the frond. By late summer these dots (sori) have turned dark brown and are covered by a protective membrane. Some species have separate or “fertile” fronds, many being woody and upright, that produce the sori. Sori produce sporangia or the precursors to spores. After the sporangia mature in the spring the sori will split catapulting the spores away from the parent fern. If the spores find a suitable substrate they will develop into a gametophyte or the stage in which the sexual organs are formed. The gametophyte develops root-like hairs and its male and female organs grow. The sperm can move in any direction but the single egg cell per gametophyte sends out chemical signals to encourage a sperm to fertilize it. But don’t be mislead as ferns use the same tactics as flowering plants to avoid self-pollination such as male and female organs maturing at different times, and chemical signals that attract sperm influences sperm from other than the initiating gametophyte. The now fertile egg then divides and begins development of a new sporophyte which sends a root down into the soil and a stem grows upward. Up to this point may take two weeks and the new, young ferns become evident in about three months depending on conditions and species.
Gallery of Selected Local Ferns
Ostrich Ferns (Matteuccia struthiopteris) are large and can grow a metre or so tall in big clumps. It was so named because its gracefully arching plumes resemble ostrich feathers. The is the only fern with edible fiddleheads in the spring. If harvesting, be sure to only take a few fiddleheads per fern. Ostrich ferns are colonizers as it spreads readily underground yielding an ever-expanding patch which is great for producing more fiddleheads! It grows in rich woods and places with wet or damp soil.
Christmas Fern (Polystichum acrostichoides) has dark green fronds once used for decoration at Christmas time because they stay green year-round. This evergreen fern grows to a half metre tall and spreads slowly producing multiple crowns in its preferred moist, rocky woodland areas. It is easily maintained and cheery with green fronds during the bleak winter.
Common Polypody (Polypodium virginianum) is an evergreen and vigorous fern that forms a lustrous mantle over rocky surfaces and is most luxurious in damp shade on north-facing rocks. It also likes stumps and old logs. Fronds with smooth pinnae are about 20 cms long and can be erect or prostrate.
Sensitive Fern (Onoclea sensibilus) has sterile, upright fronds, to a half metre tall, with prominent netted veins. It often forms large colonies from spreading rhizomes in woodlands, wet meadows and even ditches. The fronds change from green to brown immediately at first frost (hence its name) leaving the brown fertile spikes to persist through winter releasing spores the following spring.
Northern Lady Fern (Athyrium felix-femina) is a showy, vigorous fern with lacy-cut yellow-green fronds growing in small clusters. This fern, up to a metre tall, is common in our area in moist woods, swamps and fields and is often identified by the dark brown scales on the lower, sometimes reddish stem.
Marginal Wood Fern (Dryopteris marginalis) is a leathery, evergreen woodland fern growing in clumps amid roots and rocks. It can be common on rocky wooded slopes and forest edges in well-drained soil. The fronds are up to 75 cms long and arching, blue green above to light green underneath.
Maidenhair Fern (Adiantum pedantum) has graceful, fan-shaped fronds that arch in a horizontal or slightly pendulous manner and up to a half metre tall. One of the most beautiful, delicate ferns it likes moist, rich woodland soils where its rhizomes slowly creep.
Cinnamon Fern (Osmunda cinnamomia) is a large, distinctive, clump-forming fern of wet woods and meadows. The sterile fronds are up to 1.5 m long often erect and arching. The distinctive fertile fronds turn cinnamon-brown (hence its name) and persist through to spring.
Royal Fern (Osmunda regalis) is truly a large, magnificent fern of low woods, wet meadows and stream banks, marshes and bogs, often in acidic soil. The bright green, red stemmed fronds grow in erect clusters about a metre tall. At the tip of the fronds are sterile pinnae. This distinctive fern may resemble a plant from the pea family close up.
Spinulose Wood Fern (Dryopteris carthusiana) is a large, lacy clump-forming fern with fronds to 80 cms long. It likes humus-rich, moist forest soils. The fronds are largely triangular with pale brown scales on the stem. The rhizome is thick and creeping and it is an easy, adaptable fern. Another name is Florest’s Fern which tells you about its desirability.
Interrupted Fern (Osmunda claytoniana) is another large, distinctive fern with coarse fronds up to 90 cms long. A distinguishing feature are the fertile pinnae that grow at the centre of the fronds. It grows in an arching clump often in fairly well-drained soils as well as wet areas. Easily grown in moist acidic soil in lightly shaded, moist beds.
Oak Fern (Gymnocarpium dryopteris) is a small, delicate bright green fern that tilts parallel to the ground. The fronds are triangular and up to 30 cms long. It is found in cool, rocky woods and even swamp margins and is slow to expand. It gives a light airy effect.
Why Plant Ferns?
Ferns are magnificent foliage plants for shady areas. Their main role in the garden is to provide architectural form and foliage texture that contrasts with other plants. We don’t expect them to have colourful flowers although some have patterned fronds or other textural accents like separate, woody, fertile fronds. We appreciate them for their reliable, long-lasting greenness and dependable structure. Some native ferns are becoming more and more available through the commercial plant trade in garden centres. You can also consider non-native commercial ferns such as the Japanese Painted Fern and Ghost Ferns which are both fully hardy in our area. Both of these non-natives will also create substantial clumps even as their total height is typically less than 40 cms. Treat these non-native ferns as you would other woodland plants.
Collecting and Planting Ferns
Beyond the brief species descriptions provided here you may wish to take along a field guide to help ensure proper identification and, obviously, do not harvest plants in a conservation area or without permission to enter private land. Be sure to have considered what size or type of fern is suitable for your garden site. You must be able to replicate the fern’s growing conditions in your garden. Also only harvest where there is a healthy population and taking just one or two plants, being sure to get the underground rhizomes intact. The key to collecting ferns locally is to be minimalist in what you take and rely on a small number of plants to propagate themselves or otherwise expand with growth of their rhizomes. You may have to search different areas and garden centres to find species you would like to bring into your garden. For growing ferns, moist shady habitat can be found near evergreen trees with their dense branches that hold warmer air closer to the ground in winter, diffuse winds and create a suitable microclimate for ferns. While their needles take longer to decompose than leaves they will still make a good, and somewhat acidic mulch that ferns like. Deciduous trees allow more light to reach the ground from fall to spring so evergreen ferns are ideal. Rain easily penetrates to the soil allowing good hydration. In addition, their fallen leaves decompose to establish the ideal forest mulch that ferns so love. Keep in mind that tree roots can take a lot of the moisture and nutrients out of the soil so don’t plant your ferns too close to them. How fast some ferns can expand will help you decide if you have room for that growth. If not chose different ferns. Check your soil conditions and amend with moisture retaining materials and compost as necessary. Local ferns have evolved to grow in our clay-rich soils but they still need lots of leaf mould and good quality soils to thrive. So do your homework to prepare your plan before going to collect, or purchase. You may be lucky to know local or MHS gardeners who has extra ferns in their gardens!
As already indicated check your local garden centre’s ferns as I have been noticing more native fern species showing up these past few years. Plus the non-native species have also been well represented so garden centres may be a good place to start if you are just beginning to introduce ferns to your garden.
In siting your ferns there are some useful considerations including whether there will be suitable backlighting to highlight your ferns in the shade. Those with strong architecture and interesting foliage are easiest to set off this way and sun rays streaming through shows off delicate and colourful fronds. Dappled lighting is best for groundcover ferns or bringing out the texture of those with matte foliage. Those with pale-green fronds show well in darker settings. It will be necessary to water your ferns for the first years of their settling in and, depending on the species’ needs, may be required on an ongoing basis. Growing species that really like wet conditions can be a bit more challenging unless you have a pond or stream edge or create boggy conditions by burying a concave water holding layer, such as a garbage can lid, plastic or metal saucer or other water-holding container. Once filled with soil and mulch the water will remain and not simply drain downward. You may have to periodically add more water to keep the boggy conditions stable. The large and dramatic Cinnamon and Royal ferns can tolerate roots in standing water.
You can also consider what other plants to place alongside your ferns. A medley of plants creates visual interest and there are endless possible combinations so experiment. Many plants mix well with ferns and foliage, texture and form are useful considerations in addition to sharing similar growing conditions. Some typical companions are hostas (think about size and colouring), epimediums, hellebores, astilbes, trilliums, geraniums, primroses (both low-growing and candelabra varieties) and Brunnera such as “Jack Frost”. Whatever you choose the result will be augmented by contrasting the ferns with large leaves, geometric patterns, and even ephemerals that are best evident early in the year like bloodroot, spring bulbs, violets, and woodland wildflowers.
In siting your ferns there are some useful considerations including whether there will be suitable backlighting to highlight your ferns in the shade. Those with strong architecture and interesting foliage are easiest to set off this way and sun rays streaming through shows off delicate and colourful fronds. Dappled lighting is best for groundcover ferns or bringing out the texture of those with matte foliage. Those with pale-green fronds show well in darker settings. It will be necessary to water your ferns for the first years of their settling in and, depending on the species’ needs, may be required on an ongoing basis. Growing species that really like wet conditions can be a bit more challenging unless you have a pond or stream edge or create boggy conditions by burying a concave water holding layer, such as a garbage can lid, plastic or metal saucer or other water-holding container. Once filled with soil and mulch the water will remain and not simply drain downward. You may have to periodically add more water to keep the boggy conditions stable. The large and dramatic Cinnamon and Royal ferns can tolerate roots in standing water.
You can also consider what other plants to place alongside your ferns. A medley of plants creates visual interest and there are endless possible combinations so experiment. Many plants mix well with ferns and foliage, texture and form are useful considerations in addition to sharing similar growing conditions. Some typical companions are hostas (think about size and colouring), epimediums, hellebores, astilbes, trilliums, geraniums, primroses (both low-growing and candelabra varieties) and Brunnera such as “Jack Frost”. Whatever you choose the result will be augmented by contrasting the ferns with large leaves, geometric patterns, and even ephemerals that are best evident early in the year like bloodroot, spring bulbs, violets, and woodland wildflowers.
References: Ferns of the Ottawa District, William J. Cody, Agriculture Canada 1978 (available online with local maps of fern species’ sites); Ferns & Allies of the North Woods, Joe Walewski, Kollah+Stensas Publishing 2016; Peterson Field Guide to Ferns of Northeastern and Central North America, Houghton Mifflin, 2005; The Complete Book of Ferns, Mobee Weinsein, Quarto Publishing, 2020
MHS Feb 2025