Are you seeking the ideal groundcover for your garden beds or paths? Read on for the low down on features to look for and for plant suggestions.

Growth traits of good groundcovers

An ideal ground cover planting has characteristics that go beyond simply covering the soil.

• They’re often low-growing, sited beneath and around or between trees, shrubs, grasses and forbs and at the edge of beds. Their use balances space in the landscape, and allows more sunlight and air into an area. Don’t discount taller groundcovers, though, like Bee Balm (Monarda spp.) which can bring both beauty and ecological function to the landscape. A shorter species, Eastern Bee Balm (Monarda bradburiana), native to the southern and central US, blooms in spring, is 30-60 cm tall, and has fragrant flowers and foliage. It spreads more slowly than our native Wild Bergamot (Monarda fistulosa) and makes a beautiful, spring-blooming groundcover.
• They’re usually low-maintenance, requiring little to no supplemental water or fertilizer after establishment.
• They’re often evergreen or semi-evergreen.
• They’re often mat-forming with dense growth to inhibit weeds, protect soil, and conserve moisture.
• They spread quickly, through rhizomes, stolons, tip layering, or offsets, forming a dense cover. They are good garden ‘thugs’, important to outcompete invasives and ’weeds’ as we plant our gardens and replace our lawns. 

Embracing the ‘thugs’: how good groundcovers reproduce vegetatively

• Rhizomes: horizontal underground stems (below left, rhizomes of daylilies ((Hemerocallis))
• Stolons: above-ground stems or runners (below right, Bugleweed (Ajuga))

• Tip layering: stems produce roots when they contact soil. Below left, Cutleaf Stephanandra (Stephanandra incisa ‘Crispa’) has arching branches which root when the ends touch the soil.
• Offsets: small bulblets/plantlets produced at the base of mother plant. Below right, Hens and chicks (Sempervivum tectorum)

Use caution when selecting a  groundcover

Unfortunately, many of our ‘traditional’ groundcovers are exotic species which spread so well that they have become invasive threats to native plant communities far beyond the gardens in which they were initially planted. A groundcover like English Ivy (Hedera helix) is extremely difficult to remove once established. It has spread aggressively into natural spaces, displaced important natives like Trout Lily (Erythronium americanum) and Zigzag Goldenrod (Solidago flexicaulis), and has in effect, created ivy ‘deserts’.

Unfortunately, gardeners cannot rely on garden centres to sell exclusively non-invasive plants. Below left, Goutweed (Aegopodium podagraria), and right, Periwinkle (Vinca minor), both invasive, yet still sold in some Ontario garden centres.

When considering adding a new non-native plant to the garden, the following websites are helpful in assessing its sociability and aggressive nature:

• Invasive Exotic Plant Species Ranking for Southern Ontario.png
• Species – Ontario Invasive Plant Council 
• Invasive Plant Atlas of the United States – Database of Plants Invading Natural Areas: 

In addition to the above growth traits, groundcovers should provide resources for wildlife, from habitat which includes protection from predators and the elements, to sources of nectar and/or pollen for pollinators, seeds and fruits for birds, and host plants for lepidoptera. If biodiversity is your priority, perhaps a ‘living green mulch’ is a superior choice. While groundcovers are traditionally planted as a single species, living green mulch is comprised of a range of compatible native plant species which can support a diversity of wildlife. 

Where to use groundcovers in the landscape

Edging a path or patio

Use ground covers along the edge of a path or patio to soften the edges and to expand the visual width, adding dramatic blocks of colour and texture to the garden.

For spring bloom in shade/part-shade along a path, try, below left, Golden Groundsel (Packera aurea) or below right, Round-leaved Ragwort, (Packera obovata). The two rhizomatous, closely related, native species differ primarily in leaf shape and drought-tolerance. Their  ragwort foliage is toxic and avoided by deer and rabbits. The small yellow daisies are frequented by a myriad of native bees, hover and tachinid flies, and beetles. 10-15 cm tall

Below, left, Packera aurea prefers moist shade and is not drought tolerant. It has heart shaped leaves. Below right, Packera obovata tolerates full sun to partial shade and drier soils. It has oval leaves with toothed markings

A few other recommended native or near-native groundcovers for a shady path include:

• Wild Ginger (Asarum canadense) for moist, well-drained soil. 10-30 cm tall
• New York Fern (Thelypteris novaboracensis) which spreads quickly by rhizomes. 30-60 cm tall
• Oak Sedge (Carex pensylvanica) for dry to average soil, in full to part shade, evergreen. 15-30cm
• Plantain-leaved Sedge (Carex plantaginea) forms dense clumps that can be divided every 3-4 years. Average soil, 20-30cm.
• Green and Gold –Chrysogonum virginianum is mat-forming, semi-evergreen, prefers some moisture but will tolerate drought once established. 15-30 cm tall
• Dwarf Crested Iris (Iris cristata)  spreads quickly by rhizomes, great for edges of woodlands and paths; brings blue, perhaps nature’s rarest colour, to the garden. 10 cm tall
• Woodland Phlox (Phlox divaricata) for rich, moist well-drained soil. Spring-blooming with fragrant, bluish lavender flowers. 25-50 cm tall

For a sunny edge along a path or border, try our native Prairie Smoke (Geum triflorum) below left, spring blooming, salt-tolerant, with lovely seedheads and beautiful reddish fall colour. 15-30cm
On the right, non-native Lamb’s Ear (Stachys byzantina) makes a lovely full sun groundcover with its silvery-white fuzzy leaves. 30-60cm. For a shorter variety, try Lamb’s Ear ‘Little Lamb’, only 6-13 cm tall.

Female wool carder bees like the one pictured below “card” the soft, woolly hairs from the leaves of Lamb’s Ear and other fuzzy-leaved plants like great mullein (Verbascum) to line their nests.

Additional recommended ground covers for full sun to border a path:

• Wild Strawberry  (Fragaria virginiana) forms dense mats, native, 10-20 cm tall Native
• Prairie Alumroot (Heuchera richardsonii) for dry soils, late spring-summer bloom, slowly forms clumps, Ontario native,  30-60 cm tall
• Dwarf tickseed (Coreopsis auriculata ‘Nana’) for sandy soils, plants form colonies via runners, spring-summer yellow daisies,  20 cm tall, nativar 
• Threadleaf Tickseed ‘Zagreb’  (Coreopsis verticillata ‘Zagreb’) for dry soils, lovely fine foliage, small yellow summer daisies, 30-45 cm tall, nativar
• Moonbeam Tickseed (Coreopsis verticillata ‘Moonbeam’) for dry soils, fine foliage, soft yellow daisies in summer,  45 cm tall,  nativar
• Near-native Wild Petunia (Ruellia humillis) for dry, sandy, rocky soils in full sun. Great hummingbird plant, blooming in mid to late August in my garden.
• ‘Chartreuse on the Loose’ Catmint (Nepeta ‘Chartreuse on the Loose’ ) prefers drier soils in full sun and has chartreuse yellow, aromatic. foliage and blue flower spikes.  20 cm tall Non-native cultivar.

Groundcovers between pavers

Some groundcovers which can tolerate foot traffic work well between pavers in a path, and as a substitute for turf grass in the lawn to support wildlife.

Two plants for paths are below left, spring-flowering Irish Moss (Sagina subulata), which is not really a moss but a member of the Carnation family and right, Woolly Thyme (Thymus pseudolanuginosus), with hairy grey foliage and pollinator-attracting pale pink summer flowers. Both are European natives

For pavers and lawns, try non-native Elfin Thyme (Thymus serpyllum ‘Elfin’), below left, a very low, cushion-like non-native cultivar, and below right, Heal-All (Prunella vulgaris var. lanceolata), a native which grows taller, to 15cm or more.

Creeping Speedwells are low-growing, quick spreading plants, with lavender to blue flowers. They are perfect groundcovers for paths and lawns. Below left, Veronica ‘Tidal Pool’, a hybrid introduction from the Chicago Botanic Garden, dense, fast-spreading, flowering in early spring, 5cm tall, and right, Woolly Speedwell (V. pectinata), 2.5 cm, for full sun, well-draining soil. Both are deer/rabbit resistant, for Zone 5. Native to Turkey.

Another group of beautiful native groundcovers to replace lawns or use in pathways is the sedges (Carex spp.). Native sedges are important lepidopteran larval host plants that have been long overlooked in the garden nursery trade. Some do better in moist, well-drained soil, while others like Oak Sedge (C. pensylvanica) are extremely drought tolerant once established. Oak Sedge also spreads quickly to form a refreshing, green, grassy carpet that tolerates some foot traffic. For more information on Ontario native sedges, see Top Native Sedges For Your Garden — In Our Nature

Stabilizing a slope, reducing erosion and water runoff

For stabilizing steeper slopes, a mix of native plants is best, given their extensive root growth as pictured below, left. On the right, a slope in the Brooklyn Botanic Garden stabilized by a mixture of native grasses and forbs.

The following plants are a few of many that can be used as groundcovers or green mulch covers in full sun on slopes in drifts or as single species intermingling with other natives.

Grasses:

• Prairie Dropseed (Sporobolus heterolepis) is a warm-season bunchgrass that tolerates dry soils, has lovely airy seedheads and bronze fall colour. Useful as a formal groundcover or  for hillsides and berms. 60 cm tall
• Little Bluestem (Schizachirium scoparium) is a warm-season, clumping  grass with lovely blue hues in the spring and copper tones in the fall. While the straight species is 90+ cm tall, shorter varieties like ‘Chameleon’ at 60 cm may be available.
• Junegrass (Koeleria macrantha) is a cool-season clumping grass with decorative seed heads. 90 cm tall

 Forbs

• Native Eastern Bluestar (Amsonia tabernaemontana) and non-native Hubricht’s bluestar (A. hubrichtii),  members of the dogbane family, bring blue flowers to the late spring garden. They support native bees and hummingbirds, are a lepidopteran host plant, and have hollow-stems for stem nesting bees  For full sun /part shade.  Lovely golden fall colour. 60-90 cm tall. Deer-resistant. A bit slow to establish, but well worth the wait.
• Creeping Phlox (Phlox subulata) is effective planted in drifts of pink, white or purple when in bloom in the spring. Deer resistant. 10-15 cm tall
• Goldenrods (Solidago spp.) are  keystone species in eastern Ontario ecosystems. Approximately 130 species of lepidoptera use goldenrods as their larval host plant, and 42 species of specialist bees require their pollen for their larvae. They are a critical nectar and pollen food source for fall migratory and overwintering  pollinators. Goldenrods are also excellent tea plants. Three spreading Goldenrods which are less aggressive than our Canada Goldenrod (S. canadensis) are Gray Goldenrod (S. nemoralis), 45-120 cm tall, Rough-stemmed Goldenrod (Solidago rugosa) 90+ cm tall, and perhaps the most striking, Showy Goldenrod (Solidago speciosa) 90 cm tall.
• Black-Eyed Susan (Rudbeckia fulgida) is a great choice for a slope. Blooms late summer to fall. 60-90 cm tall
• False Indigo spp. (Baptisia spp.) These are nitrogen fixers with beautiful pea-like foliage and in the case of Ontario introduced species, lavender-blue June flowers. The three shorter species are the blue Dwarf False Indigo (Baptisia australis var. minor) at 45-60 cm tall, Cream Wild Indigo (B. bracteata), native to north and central US at 24-46 cm. with showy, cream-coloured flowers, and Small Yellow Wild Indigo (B. tinctoria), a rare Ontario native, 30-90 cm tall, with yellow summer blooms. Baptisias are clump-forming, slower spreaders.
• Aromatic aster (Symphyotrichum oblongifolium). Native to the US, this stoloniferous aster species tolerates drought and does well on slopes. Beautiful late September-October purple bloom. 30-90 cm tall.  Symphyotrichum species are also keystone species as larval host plants for over 100 species of lepidoptera, and pollen sources for 33 species of specialist bees. This aster and the one below are  important late season sources of nectar and pollen for our pollinators.
• Sky Blue Aster (Symphyotrichum oolentangiense) is a native, rhizomatous, fall-blooming aster similar to Aromatic Aster but with a different growth habit. Drought-tolerant once established, blooming earlier in the fall with bluish-purple flowers. 60-90 cm tall 

Shrubs   

Several native shrub cultivars are excellent, low, groundcover choices to stabilize slopes in sun/ part-sun: below left, Fragrant Sumac (Rhus aromatica) ‘Grow-Low’  60- 90 cm and right, Black Chokeberry (Aronia melanocarpa) ‘Ground Hug’ 20-35 cm.  

Snowberry (Symphorocarpos albus) is a pretty, suckering, shrub with bluish-green, small, oval leaves, and white berries in the fall and winter. It is extremely drought-tolerant, tolerating dry, rocky, soils. Snowberry is one of the larval host plants of the fascinating diurnal Snowberry Clearwing Moth (Hemaris diffinis). For an evergreen shrub groundcover, try our native Creeping Juniper (Juniperus horizontalis) or one of its many attractive cultivars. 10-30 cm tall.

Colonize and beautify a challenging area

Some native groundcovers have adapted to quickly cover difficult sites. Below are a few examples:

• For a moist, full-shade site, try native, rhizomatous, Ostrich Fern (Matteuccia struthiopteris) which has tall, beautiful fronds and in spring, edible fiddleheads when cooked. Deer resistant. 90-180 cm
• Native but endangered in Ontario, rhizomatous White Wood Aster (Eurybia divaricata), pictured below, grows in dry, deciduous forests. It blooms from late August through September in my garden, providing late-season nectar for migratory or over-wintering pollinators. It’s a lepidopteran larval host plant, and its seeds are eaten by small mammals and deer. 30-90cm

• Also, for dry shade, non-native Barrenworts (Epimedium spp.) spread to form colonies of beautiful, heart-shaped leaves often with reddish or bronze veins. Their bright, spidery flowers in early May are popular with bees and hummingbirds. The fastest spreading species in my garden have been the yellow-flowered Epimedium x Versicolor ‘Sulphureum’ and E. x rubrum. Deer and rabbit resistant.

• For full sun, on a dry, rocky, slope, try native Pussytoes (Antennaria plantaginifolia) pictured below, deer resistant, and host plant for the American Painted Lady butterfly (Vanessa virginiensis). Pussytoes also makes a lovely edging for a border or path.

• For a shady, moist, ditch, or woodland floor, try our native, rhizomatous, Mayapple (Podophyllum peltatum), initially slow to establish, but eventually forming a dense carpet. Spring-blooming. Because it goes dormant in summer, interplant with other low-growing natives like native Oak Sedge (Carex pensylvanica), Wild Ginger (Asarum Canadense), and Foamflower (Tiarella spp.).  All plant parts except the flower/fruit are toxic. 30-45 cm tall. For fruit, two genetically distinct plants are required as Mayapple is not self-fertile.

Retain moisture, supress weeds and provide soft landings under a tree or shrub canopy

Perhaps the best resource for groundcovers under trees is Heather holm’s site Soft Landings – Bee and Pollinator Books by Heather Holm which includes lists of plants most of which are native to eastern Ontario. Gardeners can choose between a fast- spreading single species native groundcover or a diversity of species.

Screen spent foliage of spring empherals

Last but not least, groundcovers are ideal in the front/middle of beds to weave through other plants, effectively covering dying foliage of early spring ephemerals.

I love scramblers, that is, groundcovers that start small, but spread rapidly with a loose growth habit that quickly fill in gaps between other plants, adding mid to late-season colour. Some of my favorites: below, left, Geranium ‘Rozanne’and right, G. ‘Blushing Turtle’, both non-native, long-blooming, in full sun from early summer to fall, low-growing at 30 cm, but vigorous growers which will easily fill in spaces in the garden. Geranium ‘Rozanne’ will spread more extensively throughout the front of a border.

Purple Poppy Mallow (Callirhoe involucrata) is another full sun scrambler which is low-growing at  15-30 cm. It is drought-tolerant and has striking, cup-like, magenta flowers over much of the summer. Purple Poppy Mallow is native to the central US. Site it with care- rabbits love it on my property!

Another scrambler in my garden is the prostrate cultivar ‘Snow Flurry’ of our native Heath Aster (Symphyotrichum ericoides). It blooms from late summer through fall, and is loved by bees, butterflies, skippers, and  moths. It is the larval host for Silvery Checkerspot and Pearl Crescent. ‘Snow Flurry’ is 10 cm tall, and is perfect for rock gardens, and the edge of paths and borders. Rabbits love it as well, so site it with care.