Try these weed-smothering, attractive, spreading (but not invasive!) plants.

Who doesn’t want a garden that requires less weeding? For landscapers and their clients it means a more consistently attractive landscape, less time spent on maintenance, and more time that can be directed toward other projects on the property. With the passing of the years, weeding has become more challenging for me as a gardener and in the spirit of comfort, I have become a firm advocate of weed smothering groundcovers. I still remember the days when pachysandra, myrtle (vinca), and English ivy were the big three groundcovers. Today, their aggressive tendencies have resulted in banishment to invasive plant lists, but there remain many great plants from which to choose!

Groundcovers

A lush sweep of oak sedge, or Carex pensylvanica, makes a typically carefree grassy groundcover.

 

Mulch Madness

Lately, I have found it interesting how the current groundcover of choice appears not to be a plant, but mulch. I have nothing against mulch, especially while plants are becoming established.  A 2″ to 3″ thick coating of shredded bark or wood chips does wonders for suppressing weeds, retaining soil moisture, and reducing soil erosion.

The problem with mulch, though, is twofold. First, it is often applied in excess. It doesn’t follow that 6″ is twice as good as 3″ of mulch! Thick applications encourage shallow roots and eventual drought stress. Second, mulch is often applied in lieu of plants. Remember, mulch is not sustainable. It requires energy to make, deliver, and spread, while a ‘green mulch’ of appropriate plants is able to thrive with minimum input. Non-invasive plant selections require minimal maintenance, add texture and color, can provide habitat for beneficial insects, reduce weeds, and reduce the amount of mulch.

Plants To Try

Japanese Forest Grass (Zone 5-9). One of the more troublesome weeds to control is Microstegium vimineum, otherwise known as stilt grass or packing grass. It seeds with gusto and manages to grow through nearly every plant, except Japanese forest grass, or Hakonechloa macra (pictured on page 22). Native to the volcanic region around Mt. Hakone, forest grass will grow from 18″ tall in well-drained shade to nearly 3′ tall in moist, fertile soils. In fact, it’s one of the few ornamental “grasses” that will grow in shade. The plants slowly spread by rhizomes or horizontal stems to create a dense mat of gracefully arching foliage. I have never seen it self-seed and it is rare that you will ever see a weed penetrating through the canopy, even stilt grass.

Forest grass is also beautiful. There are several selections with colorful foliage, of which ‘All Gold’ is a wonderful selection. Its chartreuse foliage is most stunning in May through July, becoming increasingly green as fall approaches. ‘Aureola’ is another nice form with yellow and green striped foliage that often develops various shades of pink come autumn’s frost. The straight species turns yellow in autumn and finally tan for the winter, with stems of all the selections collapsing under snow load, resulting in minimal Spring cleanup to follow.

Groundcover Alternatives

Japanese forest grass has an elegant form, but stands tough against stilt grass. It’s also one of the few “ornamental” grasses that will grow in shade. Several selections have colorful foliage, like All Gold or Aureola.

Oak Sedge (Zone 5-9). If you like grassy foliage as a groundcover, but are looking for a North American native, consider oak sedge, or Carex pensylvanica (pictured opposite page, top left). The plants are also rhizomatous, creating a dense weed-suppressing mat that flourishes best, believe it or not, in dry shade! The advantage of oak sedge is its carefree nature. It typically requires no irrigation, fertilizing, weeding, or cutting back come Spring, although I have seen some stilt grass and Norway maple seedlings successfully seed in.

Come winter, the foliage turns tan and mats down, serving as a mulch for the emerging new foliage the following Spring. Around mid-June here in New Jersey, the previous year’s foliage is completely hidden and starting to decay (the image shown was taken on June 18th). For the shade garden, this sedge is the perfect living mulch. Plants such as hosta, snakeroot, or hydrangea can be planted directly into and through the planting. I should also mention that neither forest grass nor oak sedge are beloved by deer.

Cranesbill or hardy geranium (Zones 3-9 depending on variety). This perennial geranium can also make an impressive ground cover. One of my long-standing favorites is Geranium macrorrhizum, commonly called bigroot geranium. It does, in fact, feature thick rhizomatous stems that resemble a big root! Spreading fairly quickly, the palmate or maple-like foliage emits an attractive fragrance when disturbed, which is also effective for keeping deer at bay. Shrubs like sweet pepperbush, or summersweet (Latin name of Clethra alnifolia) appreciate the cooler root run this plant affords.

Come Spring, cranesbill displays attractive pink to magenta flowers and in late Autumn through Winter, the foliage is often painted with splashes of orange, purple, and red. I would not consider the foliage as evergreen as juniper, for instance, but it does persist throughout the Winter months. It’s best grown in shade, but tolerates full sun in moister areas.

Barrenwort (Zones 5-8). Another phenomenal ground cover for shade and morning sun are the various species and selections of Epimedium, commonly known as barrenwort. This is a genus I have used ‘career’ in gardening. However, over the past few years numerous new selections have appeared with ever more dramatic flowers and foliage.

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Epimedium species are native from the Caucus region east to Japan with flowers that vary in color from white, to yellow, pink, and purple. The flowers adorn the plant in Spring on flower stems ranging from 10″ to 36″ tall! The foliage is usually heart-shaped with red highlights, especially in Spring, and it typically reaches heights of 10″ to 14″ tall. Some species have attractive spines (but not painful) along the leaf margin, while others have a smooth leaf margin. Some species are clump forming, but most selections spread moderately by rhizomes to create dense and very long-lived groundcovers. Many of the selections are extraordinarily drought tolerant, enduring month long droughts without any apparent indications of stress.

If you are in search of a large-flowered form, consider ‘Amber Queen.’ It’s a 2006 introduction and has large yellow flowers with long spurs, forming a flower close to 1½” in diameter. Even more dramatic, the flowers appear on willowy stems reaching upwards of 30″ tall! Another large-flowered form introduced in 2004 is ‘Domino.’ This cultivar sports flowers with long white spurs and a maroon central cup that appear abundantly on 24″ tall stems. Both feature attractive and near evergreen foliage with finely spined leaf margins. Clearly, this is a genus landscapers should explore further.

Embrace Tall Groundcovers

A misconception shared by many is that plants with flower stems reaching 24″ to 36″ tall are not befitting of groundcover status. Yet I have come to think of a groundcover as something that covers the ground well and effectively smothers out weeds. The height of the plant is less of a defining characteristic.

Mountain mint (Zones 4-8). One plant my students always discredited as a legitimate groundcover is mountain mint, or Pycnanthemum muticum, since it annually grows to 24″ to 30″ tall (pictured on previous page). Roughly native from the Mississippi River to areas east, it does a wonderful job of densely covering the ground and has been used successfully at Central Park in NYC to suppress weeds and reduce maintenance! Much like a typical mint, the stems are square and the foliage is very aromatic when rubbed. In fact, the foliage contains pulegone, an oily compound that smells like peppermint and is rather effective at repelling mosquitoes when rubbed on the skin! As is true of most plants with scented foliage, it is very deer resistant.

However, unlike typical aggressive mints, the plant spreads mildly by rhizomes and is not problematic in smaller spaces since the rhizomes are shallow and easily removed where it overgrows boundaries. From June through September, the tip of the stem is adorned with silvery, two bracted flowers, upwards of 2″ in diameter that are much beloved by pollinators. Similar to flowering dogwood (Cornus florida), the actual flowers are very small and the primary display is created by the modified leaves called bracts.  These silver bracts provide a beautiful shimmering effect for well over three months!

Groundcover Alternatives

Crawford asserts a groundcover doesn’t need to be low-growing to cover well and suppress weeds. Mountain mint (above) is a tall, native pollinator that has been used successfully in Central Park, NYC to reduce weeds and maintenance. Giant Solomon’s Seal (below) is deer resistant and native. (All photos courtesy of Crawford)

Groundcover Alternatives

The central boss of concentrically arranged flower buds yield small white flowers with purple markings. Plants prefer full sun to partial shade in soils that are rich in organic matter and not prone to excessive drought.

False Solomon’s Seal (Zones 3-9). A 2018 honorable mention Plant of the Year by the Garden Club of America (GCA), false Solomon’s seal, or Maianthemum racemosum (formerly known as Smilacina racemos), is a three-season woodland beauty. With fragrant white panicle flowers in Spring, arching stems, and ridged green leaves, it provides a graceful architectural form through Summer and golden foliage and showy red berries in Fall. False Solomon’s seal colonizes naturally in shade or partial shade, is extremely resilient, adaptable, low-maintenance, hardy, and provides nectar for pollinators and food for wildlife. That being said, my false Solomon’s seal is always eaten by the deer. Giant Solomon’s seal (Polygonatum biflorum var. commutatum, pictured on previous page) is also a great plant, more deer resistant, native, and not planted enough. Hardy from zones 3 to 7, leaning stems grow from three to seven feet.

Clearly, there are many plants that serve as attractive groundcovers and most have yet to receive their much-deserved accolades. They provide color, reduce the need for annual mulching, cool the soil, and make property maintenance easier by reducing those pesky weeds!

Bruce Crawford

Crawford is currently manager of Horticulture at Morris County Parks Commission in NJ. In his lengthy Green Industry career, Crawford owned a design/build garden design business for nearly 25 years that specialized in plantings for year-round interest. He was also an adjunct professor in Landscape Architecture at Rutgers University, and served as Director of Rutgers Gardens for 17 years, which involved the management of the 180-acre facility, including designed gardens, woodlands, open fields, and a green roof featuring mostly native plants.

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