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Hardy and vigorous ferns

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Ostrich fern.
Photo: Jardin botanique de Montréal (Michel Tremblay)

The ferns listed here are all vigorous growers, establishing themselves quickly in the right conditions and, in many cases, forming a dense ground cover that blocks out most weeds.

Gardening communities in temperate regions around the world are familiar with ostrich fern (Matteuccia struthiopteris), an easy-to-grow, highly ornamental species. Growing it at home can help limit the damage done to colonies in the wild when people head out in the spring to gather the ever-popular “fiddleheads”. You are bound to be more cautious about collecting fiddleheads if you grow the fern yourself, and will take only one or two from each mature crown per year if you don’t want to unduly weaken your plants.

This fern is popular for its broadly lance-shaped leaves that grow over 2 metres high in the wild – it will not grow so large in your garden, depending on moisture levels in your soil. The more constant the humidity, the more lush the fern. Under the right conditions, you can even hope for fronds 90 cm high on average. Their vase-like arrangement is a definite asset, but to maintain it you must be careful to choose a site out of the wind. Because this fern is slow to appear in spring, you can pair it up with other plants that flower vigorously in the spring and that will be able to tolerate the dense shade created by its fronds later in the season. In the Shade Garden in spring, you can see a mixed colony of this fern, with its fronds not yet fully developed, along with the lovely double-flowered trilliums (Trillium grandiflorum 'Flore Pleno'). It makes for a spectacular show! Once colonies have become established, you will need to clean around their edges every two years to prevent them from spreading. It’s a perfect opportunity to share this native beauty with your gardening friends and convert them to the joys of fern gardening.

Sensitive fern (Onoclea sensibilis) can be identified by its much less deeply divided fronds, with a more lobed and triangular shape. What makes this fern vigorous is its ability to grow in either shade or sun, with ample moisture, and its preference for wet sites. As is the case for ostrich fern, the fruit-bearing parts of sensitive fern are separate from its sterile fronds, and early in the season or as soon as those fronds disappear in the fall, fertile fronds covered with “beads” containing spores can be seen.

Eastern hay-scented fern (Dennstaedtia punctilobula) sometimes has a bad reputation as a weed, despite the definite assets that compensate for its aggressive habit. It adapts well to the garden, grows equally well in shade and full sun, and forms dense carpets that make excellent ground cover on slopes. Its shallow rhizomes make it easy to dig out overly invasive parts of the plant.

If your ferns have to coexist with more delicate plants or your latest rare acquisition, or if you have limited space in your garden, you would do well to plant slower-growing species and avoid any that grow by rhizomes … like the three ferns described above.

Based on an article by Michel-André Otis in Quatre-Temps magazine, Vol. 18, No.2.

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