Best Plants for a Slope
A landscape challenge [1]
Tracy Heuermann transformed the steep grade of her Illinois backyard into a cascading garden. Here's how she did it--and how you can use her ideas in your own not-so-flat yard.
Pictured: Lush plantings soften the terrace garden walls that tame Tracy Heuermann's hillside.
Imagining the potential [4]
When Tracy first visited her future home on a one-acre site north of Peoria, she saw a treacherous hillside eroded into deep ruts.
The backyard, cultivated only with grasses, descended sharply into near wilderness. Water and gravity had steadily conspired to carry away topsoil and nutrients. Railroad ties barely held the hillside in place.
It all got Tracy's imagination churning--enough to buy the place. A longtime Master Gardener and co-founder of the Midwest Hosta Society, she could see the potential: flowers grown on inclines, ascending like clouds of texture and color to embellish the slope.
Pictured: Nine seasons' growth has transformed Tracy's garden from a rutted hillside to a lush incline.
Terraces are the key [7]
Tracy and her contractor husband, Victor, visited the inspiring hillside gardens of England's famed Chelsea Flower Show. "The terracing on the cliff overlook at Kiftsgate made me believe that we could do this in our backyard," Tracy says.
The couple carved five levels from their yard's heavy, clay-based soil and poured 12-foot concrete retaining walls to brace the tiers. About half of the height of each wall plunges below the surface of the hillside, anchoring it to the land.
To soften the look of the man-made walls and transition the garden into the surrounding woodland, Tracy incorporated free-flowing, organic design elements, such as curvy grass paths and tumbling phlox.
Pictured: Salvia, azaleas, miniature bearded irises and euonymus shroud retaining walls in Tracy's garden.
Worth the work [10]
Today, Tracy and her husband have a beautiful hillside garden overlooking the emerald panorama of the Illinois River Valley. Tracy and Victor continue to develop the garden, nurturing new specimens and caring for established ones. "It's essential that the garden bring joy to you," Tracy says. "This one's brought a lot of joy to my family."
Read the following slides for Tracy's tips on how to fight erosion and which plants to choose for a slope.
Pictured: A limestone-paver patio offers a panoramic hillside view.
From erosion to beauty [13]
Using these savvy tactics, Tracy turned eroded land into a fertile hillside.
Bind soil with sturdy roots. Any plant helps, but those with deep, clumping roots (trees, shrubs, grasses) are especially effective, as are groundcovers, which find and fill empty spaces.
Remove weeds carefully. Pulling them disturbs fragile soil. Healthy plantings and groundcovers will eventually crowd out most weeds. Until then, use mulch to smother weeds and to fortify the soil. Pull weeds when they're small. Knock dirt from roots and put it back in the ground.
Make a rock garden. Place stones or boulders among plants to trap soil and moisture and slow water runoff. You'll get a more natural look by scattering rocks of a uniform type.
Build terraces and retaining walls. It's a costly solution, and you probably need a landscape contractor for help. But terraces, softened by cascading plants such as creeping phlox, dramatically transform even the toughest terrain.
Pictured: Creeping phlox and Louisiana irises, along with a curved grass path, provide an appealing contrast to stone steps and retaining walls.
Planting on a slope: groundcovers [16]
What are the best plants for a slope? Here are some of Tracy Heuermann's best bets plus picks from The Best Plants for 30 Tough Sites, compiled by University of Minnesota Extension Master Gardeners. Recommended groundcovers are on this slide and the next 5 slides; shrubs and perennials start on slide 12.
Candytuft (Iberis sempervirens) Fragrant white flower clusters stand 12 inches tall on 'Snowflake' and 'Purity'. Zones 5-9.
Pictured: Candytuft (Iberis sempervirens)
Planting on a slope: cranesbill [19]
Cranesbill (Geranium) Tracy's favorite, 'Rozanne', spreads rapidly and bears near-opalescent purple petals. Not to be confused with pelargonium, commonly referred to as geranium. Zone 5.
Pictured: 'Rozanne' geranium
Planting on a slope: creeping myrtle [22]
Creeping Myrtle (Vinca minor) Tracy plants these deer-resistant purple, blue or white starlike flowers at the border of the forest preserve. Zones 4-9.
Pictured: Creeping myrtle (Vinca minor)
Planting on a slope: creeping phlox [25]
Creeping Phlox (Phlox subulata) This lime-green, furry mat blooms wildly with pink, red, purple or white flowers in late spring and early summer. Zones 3-8.
Pictured: Creeping phlox (Phlox subulata)
Planting on a slope: 'Flower Carpet' rose [28]
'Flower Carpet' Rose (Rosa) Spreading vigorously up to 4 feet, this groundcover rose pretties a slope with deep rose-pink blooms. Zones 5-8.
Pictured: 'Flower Carpet' rose (Rosa); photo courtesy of Anthony Tesselaar Plants
Planting on a slope: iris [31]
Iris (Iris) Siberian irises wave purple blooms in early spring; the bright green, grasslike leaves create a textural backdrop when the blooms are spent. Zones 4-9.
Pictured: Iris (Iris)
Planting on a slope: hosta [34]
Mix tough shrubs and perennials among groundcovers to add taller accents on a slope. Recommendations are on this slide and the following 4 slides.
Hosta (Hosta) A favorite for shady gardens, hostas distinguish themselves with bold leaves in shades of green. Zones 3-8.
Pictured: 'Tracy's Emerald Cup' hosta, developed by Tracy Heuermann, whose garden is featured at the beginning of this slide show
Planting on a slope: mock orange [37]
Mock Orange (Philadelphus) Extremely fragrant, this shrub blooms reliably, even in poor soils. Zones 5-8.
Pictured: 'Minnesota Snowflake' mock orange
Planting on a slope: sage [40]
Sage (Salvia) Colorful, bell-shape buds shoot off erect, spiky stems on this natural slope inhabitant. Zones 5-10.
Pictured: Sage (Salvia)
Planting on a slope: snowberry [43]
Snowberry (Symphoricarpos var. laevigatus) Tiny pink flowers burst out in summer, followed by namesake "snowball" berries, which last well into winter. Zones 3-7.
Pictured: Snowberry
Planting on a slope: weigela [46]
Weigela (Weigela) Nectar-filled magenta or white flowers draw hummingbirds. Tracy grows several varieties, including 'Wine and Roses' (Zone 4), 'Java Red' (Zones 4-8), 'Pink Princess' (Zones 5-9) and 'Polka' (Zones 4-7).
Pictured: 'Wine and Roses' weigela
(A version of this story appeared in Midwest Living® May/June 2009.)