Thursday, June 3, 2021

Ferns As Groundcovers

Strolling pathways and lanes among magnificent homes on Kiawah Island, I was impressed by the effective use of ornamental groundcovers in the landscapes.

Paths there were many,
Winding through palmy fern, and rushes fenny,
And ivy banks; all leading pleasantly
To a wide lawn, whence one could only see
Stems thronging all around between the swell
Of turf and slanting branches: who could tell
The freshness of the space of heaven above,
Edg'd round with dark tree tops?...
- John Keats - From Endymion: Book I

The ferns were among the loveliest. What makes them so are their rich textures, lush beauty, and low maintenance requirements. Ferns, in fact, could be an elegant answer to your own groundcover needs.

Before delving into the subject of ferns as groundcovers, let's consider the reasons for using groundcovers.

Groundcovers (or ground covers) are going to occur in most climates quite naturally. Just above the soil layer and below native shrubs and trees, herbaceous plants sprout and spread. They are important in the ecosystem for erosion control, providing and balancing plant diversity, conserving soil moisture, and healing the land after some sort of disturbance.

Many natural groundcover species are not all that attractive. Some are harmful; poison ivy comes to mind. Creative gardeners, however, have learned to substitute more desirable plant species to achieve those worthy ends that nature would otherwise accomplish.

So, that brings us back to the subject of ferns as groundcovers. Ferns will not serve as lawn substitutes for they grow too tall and don't survive frequent foot traffic, but it you want plants that do whatever else that groundcovers should do, require minimal maintenance, and are deer-proof, ferns could be your plants of choice.  Choosing the right fern is as simple as identifying the area you want to cover and selecting a suitable species to do it.

Once established, fern groundcovers are very impressive. Here are a few to consider.

Southern Sword Fern

Nephrolepis cordifolia

Nephrolepis cordifolia - aka Southern Sword Fern - is among the most widely used ferns in southeastern U.S. landscapes. They're tough as nails and very easy to grow.  This evergreen species presents upright sword-shaped fronds with closely spaced leaflets. They spread by runners, and tolerate drier, poorer soil than most ferns, especially in shaded areas. They'll also thrive in full sun with sufficient irrigation.

But first, take note. Southern Sword Fern is not native to the U.S., but to Australia and Asia. Therefore, it is sometimes considered to be an invasive species because it competes with native groundcover species - i.e. weeds. But given that it does suppress weeds, it seems like an ideal solution to the weed problem if used judiciously. I'll leave it to you to decide. 

Southern Sword Ferns grows to 18" tall. Recommended soil pH from 5.6 to 7.8. They're cold-hardy only in USDA climate zones 9b - 11, so they're of limited use.

Hay-scented Fern

Dennstaedtia punctilobula

Dennstaedtia punctilobula, also known as Hay-scented fern is a North American native found from Quebec to Georgia, and westward to Missouri and Arkansas. That's USDA climate zones 3 - 8. 

It is deciduous, but the fall foliage turns to a beautiful golden yellow or chartreuse (hay-colored) in fall. Grow it in full shade - not deep shade - to partial shade in soil with average moisture. 

The secret to success with any plant is to approximate it's native habitat in your own landscape. Dennstaedtia thrives in rich, deep, loamy soil with average moisture in deciduous hardwood forests.

Hay-scented fern is best propagated by planting rhizomes in well-prepared soil. It's reasonably drought-tolerant, and, of course, deer won't eat them.

Christmas Fern

Polystichum acrosticoides

This evergreen beauty is one of our most useful native ferns. Polystichum acrosticoides really stands out in winter. Also known as Christmas fern, the glossy foliage has been gathered since colonial times for Christmas greenery. I never fail to point out to my grandchildren that the leaflets are shaped like elves' shoes. 

It can be found growing naturally in shady hardwood forests from Quebec to Florida, and westward to Texas (USDA climate zones 3 - 9). Rich, loamy, slightly moist soil is ideal. Nevertheless, Christmas fern is reasonably drought tolerant. They are often available in 3-1/2 inch pots and as bare root crowns.

Autumn Fern

Autumn Fern - aka Dryopteris erythrosora - is an Asian beauty that is becoming very popular. Evergreen fronds grow 18" to 24", and newly emerging foliage has a burgundy tone. Stunning! It's cold hardy, too, thriving from USDA climate zones 5 - 8. The delicate appearance belies its toughness - so tough, in fact, that it is often used in public gardens, squares and avenue median strips, so long as the site is in partial shade to full shade.

Southern Shield Fern

Dryopteris ludoviciana

So, what if you need a fern for a sunny location? Look no further than Southern Shield fern or Southern Wood fern - aka Dryopteris ludoviciana. This gorgeous North American native is found from Kentucky to Florida, and westward to Texas. That's USDA climate zones 6 - 10. Foliage is evergreen, too. It's a big one, growing up to 48" in height! Average, slightly moist soil with pH ranging from 6.1 to 7.5 will be ideal.

There are, of course, many more ferns that could be mentioned. Some are, in my opinion, a bit too small to serve as effective ground covers. Others are gigantic. Many prefer habitats too specific to be of general interest.

I hope that these ferns I've mentioned will provide you with some inspiring choices for your own ground cover needs.

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