How to Landscape a Slope or Hillside in Minnesota (Erosion Control)

A slope is the spot in the yard everyone avoids. It is miserable and dangerous to mow, water runs straight off before it soaks in, mulch washes to the bottom after every storm, and bare patches widen into gullies that get worse each spring. If you have a hillside in Eagan, Burnsville, Stillwater, or anywhere along the river bluffs, you already know the frustration.

The good news: a planted slope is one of the highest-impact upgrades you can make. The same deep-rooted plants that hold soil in place also turn an eyesore into one of the best-looking parts of the yard — and once established, a properly planted slope is far less work than fighting to mow it ever was.

This guide covers how to stop the erosion, build the slope correctly, and choose the deep-rooted Minnesota plants that lock a hillside together for good.

Why Slopes Erode in Minnesota

Erosion happens when water moves faster than the soil can absorb it, picking up particles as it goes. Minnesota slopes face this from several directions at once:

• Heavy spring melt. A fast thaw over still-frozen ground sends huge volumes of water sheeting downhill with nowhere to soak in.
• Intense summer downpours. Our increasingly heavy convective storms dump an inch or two in an hour, far more than bare soil can take.
• Thin or struggling turf. Grass roots are shallow — only a couple of inches deep — so turf on a slope offers little holding power and often thins out, exposing soil.
• Bare mulch. Loose mulch with no plant roots beneath it simply floats away.

The permanent fix is plants with deep, fibrous, spreading roots that hold soil, slow water, and help it infiltrate instead of running off. Turf cannot do this job; the right shrubs, native grasses, and ground covers can.

Assess Your Slope First

Before choosing plants, size up what you are dealing with. The steepness changes the whole approach:

• Gentle slope (under 3:1 — drops less than 1 foot for every 3 feet across). Straightforward. Plant deep-rooted ground covers and shrubs directly; minimal structural help needed.
• Moderate slope (3:1 to 2:1). Plantable, but you will want erosion-control fabric or jute netting while plants establish, and dense planting.
• Steep slope (steeper than 2:1). This needs serious erosion control and often terracing or a retaining wall. For anything this steep, or any slope where water is already cutting channels, get professional eyes on it — a failing steep slope can become a real drainage and safety problem.

Also note where water enters and exits the slope. If a downspout or a neighbor's yard is dumping water onto the top of your hill, no amount of planting fixes that until you redirect the source. Sometimes the real solution is a swale or a downspout extension at the top.

It is also worth checking your sun exposure honestly, because it changes the plant list completely. A south- or west-facing slope in Burnsville bakes — it will be hot, dry, and fast-draining, calling for creeping juniper, sumac, and prairie grasses. A north- or east-facing bank, or one shaded by a neighbor's mature oaks, stays cooler and damper and wants sedges, wild ginger, and bigroot geranium instead. Spend a few minutes watching where the light falls across the day before you buy anything; it is the cheapest mistake to avoid.

Erosion Control While Plants Establish

The vulnerable window is the first year, before roots take hold. A few materials bridge that gap:

1. Biodegradable erosion blanket. Jute or coir (coconut-fiber) netting pinned over the slope holds soil and seed in place, then breaks down naturally as plants fill in. This is the standard for moderate slopes.
2. Live staking and dense planting. Plant more densely than you would on flat ground so roots interlock faster and cover the soil sooner.
3. Terracing. On steeper slopes, breaking the hill into stepped levels with boulders, timbers, or block walls slows water and creates flat planting pockets.
4. Mulch that stays put. Use shredded hardwood mulch — never bark nuggets, which float and roll downhill. On steeper ground, a mesh or netting over the mulch keeps it anchored.

Lay your erosion blanket, plant through it, and water gently so you do not blast out the soil before roots catch.

Deep-Rooted Shrubs for Slopes

Spreading shrubs are the workhorses of slope stabilization. Their woody, far-reaching root systems are the strongest soil-holders you can plant, and their spreading habit covers the ground to shield it from rain impact. All of these are reliably hardy in zone 4b–5a.

• Gro-Low Sumac (Rhus aromatica 'Gro-Low') — the single best slope shrub for Minnesota. It spreads 6 to 8 feet wide, suckers to knit the soil, smothers weeds, blazes red-orange in fall, and tolerates poor, dry soil and salt.
• Creeping Juniper (Juniperus horizontalis 'Blue Chip', 'Bar Harbor', 'Wiltonii') — evergreen, drought-proof, and superb on hot, dry, sunny banks where it forms a dense soil-holding mat year-round.
• Dwarf Bush Honeysuckle (Diervilla lonicera) — a tough Minnesota native that suckers to form a low colony, handles sun or shade, and holds banks effortlessly.
• Snowberry (Symphoricarpos albus) — a native suckering shrub that stabilizes slopes and feeds birds with white winter berries.
• Fragrant Sumac and American Hazelnut (Corylus americana) — larger native shrubs for big banks where you want substantial, deep-rooted cover.

For more privacy or screening on a large bank, several of the picks in our best privacy shrubs for Minnesota guide also have strong root systems suited to gentle slopes.

Native Grasses and Ground Covers

Between and below the shrubs, deep-rooted native grasses and spreading ground covers complete the erosion armor. Prairie grasses in particular send roots several feet down — far deeper than turf — which is exactly what binds a hillside.

Native Grasses (Deepest Roots)

• Little Bluestem (Schizachyrium scoparium 'Blue Heaven', 'Standing Ovation') — a Minnesota prairie native with deep roots, coppery fall color, and excellent slope-holding power on dry, sunny banks.
• Switchgrass (Panicum virgatum 'Northwind', 'Shenandoah') — tall, tough, and deeply rooted; great for larger slopes and tolerant of clay and moisture.
• Sideoats Grama (Bouteloua curtipendula) and Prairie Dropseed (Sporobolus heterolepis) — finer-textured natives for the lower, drier portions of a bank.

Spreading Ground Covers

• Creeping Phlox (Phlox subulata) — an evergreen mat for sunny slopes with a brilliant May bloom.
• Creeping Sedum (Sedum 'Angelina', 'Dragon's Blood') — succulent, drought-proof mats for the hottest, driest, sandiest banks.
• Wild Ginger (Asarum canadense) and Pennsylvania Sedge (Carex pensylvanica) — the answer for shaded slopes under trees.
• Bigroot Geranium (Geranium macrorrhizum) — weed-smothering, deer-proof, and adaptable to sun or part shade.

How to Plant a Slope, Step by Step

The technique matters as much as the plant list. Here is the sequence that works on Minnesota hillsides:

1. Time it right. Plant in spring or, better, in early fall (September) when cooler temperatures and reliable rain help roots establish before winter — see our Twin Cities planting calendar.
2. Redirect water first. Extend downspouts past the slope and add a swale or berm at the top to intercept runoff before it hits the planting.
3. Lay erosion blanket on moderate slopes. Pin jute or coir netting over the bare soil.
4. Dig individual pockets, not a tilled bed. Tilling a whole slope destabilizes it. Dig holes through the blanket for each plant instead.
5. Create small terraces or saucers. Set each plant into a tiny level shelf cut into the slope, with the downhill side bermed up, so water pools at the roots instead of running past.
6. Plant densely and stagger. Space plants closer than on flat ground and arrange them in a triangular, staggered pattern so roots interlock and water has to weave between plants.
7. Mulch with shredded hardwood 2 to 3 inches deep, keeping it off the stems.
8. Water gently and consistently the first season — soaker hose or drip is far better than a sprayer that washes soil away.

Terracing and Retaining Walls

For steep or tall slopes, plants alone may not be enough, and terracing turns an unusable bank into level, plantable space. Options range from simple to substantial:

• Boulder terraces. Naturalistic and very Minnesota; large fieldstone or granite boulders set into the slope create planting pockets and a rugged look.
• Segmental retaining-wall block. Engineered block systems are the workhorse for tidy, durable terraces up to a few feet.
• Timber terraces. Lower cost for modest height, though shorter-lived than stone or block.

An important rule in many Twin Cities suburbs: retaining walls over 4 feet tall typically require an engineered design and a permit. For anything that tall, or any wall holding back a structure or driveway, bring in a pro. A wall that fails takes the whole slope with it.

Whatever method you choose, the principle is the same: break one long, fast slope into several short, slow ones. Even a single low boulder course or a couple of timber steps partway down a moderate bank dramatically reduces how much speed water can build, and that alone can stop erosion that planting struggles to control on its own. Combine modest terracing with deep-rooted plants and you get the best of both — the structure slows the water, and the roots hold the soil between the structures.

Drainage Behind the Wall

If you do build a wall, drainage is what makes it last. Minnesota's freeze-thaw cycles and saturated spring soils put enormous pressure on a retaining structure. A proper wall needs clean gravel backfill, a perforated drain tile at the base routed to daylight, and weep gaps so water can escape rather than build up and heave the wall out over a few winters. Skipping the drainage is the single most common reason a Twin Cities retaining wall bows and fails — it is not the blocks that go, it is the trapped water behind them.

Caring for a Slope After Planting

The first full season is where slopes are won or lost. Roots are still shallow, the erosion blanket is doing most of the holding, and a single washout can undo your work. Give the planting consistent attention that first year and it largely takes care of itself afterward:

• Water deep and slow. A soaker hose laid along the slope, run for a long, gentle session, soaks in instead of sheeting off. Aim for the equivalent of about an inch a week through the first summer if rain is short.
• Walk it after every heavy storm. Spot any small rills or bare patches early and patch them with mulch and a few extra plugs before they grow into gullies.
• Weed by hand, gently. Aggressive cultivation loosens slope soil. Pull weeds by hand the first year until your plants close in and shade them out.
• Leave the blanket alone. Let the jute or coir netting break down on its own schedule — it is still protecting soil even as it frays.

By the second season the shrub and grass roots have taken over the holding job, the ground covers are knitting across the surface, and your maintenance drops to little more than an annual spring cutback and the occasional weed pull.

A Sample Slope Planting Plan

For a typical sunny suburban backyard slope, here is a planting that stabilizes the bank and looks intentional year-round:

1. Top third: a swale to catch runoff, backed by a drift of 'Gro-Low' sumac to anchor the upper bank.
2. Middle: masses of 'Blue Heaven' little bluestem and 'Northwind' switchgrass for deep roots and fall and winter movement.
3. Sunny pockets: creeping juniper and creeping sedum spilling down to hold the soil surface.
4. Lower edge: creeping phlox for a May flush of color and a finished, mat-forming bottom edge.
5. Everywhere: erosion blanket the first year and shredded hardwood mulch throughout.

That combination gives you deep-rooted stabilization top to bottom, spring phlox bloom, summer green, blazing fall sumac and bluestem color, and winter grass structure — with virtually no mowing and rapidly diminishing maintenance.

FAQ

What is the best plant to stop erosion on a Minnesota slope? Gro-Low sumac (Rhus aromatica 'Gro-Low') is the top choice for sunny slopes — it spreads wide, suckers to knit the soil, and tolerates poor, dry conditions. Pair it with deep-rooted native grasses like little bluestem for the strongest hold.

Should I use grass seed or plants on a slope? Deep-rooted shrubs, native grasses, and spreading ground covers hold soil far better than turfgrass, whose shallow roots offer little protection. Turf on a slope is also miserable to mow. Plant deep-rooted species and skip the lawn on any meaningful bank.

How do I keep mulch from washing down the hill? Use shredded hardwood mulch, never bark nuggets, which float and roll. On steeper slopes, pin an erosion blanket or netting over the mulch until plant roots take hold, and plant densely so foliage shields the soil from rain impact.

When is the best time to plant a slope in the Twin Cities? Early fall, around September, is ideal — cooler air and reliable rain help roots establish before winter without the heat stress of midsummer. Spring works too. Avoid planting a bare slope right before the heavy-rain or hard-freeze seasons.

Do I need a retaining wall? Only for steep or tall slopes, or where you want level, usable terraces. Gentle to moderate slopes can usually be stabilized with deep-rooted plants alone. Walls over 4 feet generally require an engineered design and a permit in most Twin Cities suburbs, so consult a professional for anything that tall.

Turn Your Problem Slope Into an Asset

A hillside does not have to be the worst part of your yard — with the right deep-rooted plants, it can be the best. Browse our spreading slope shrubs for Gro-Low sumac, creeping juniper, and dwarf bush honeysuckle, and our native grasses and ground covers for the bluestem, switchgrass, sedum, and phlox that lock a bank together. Three Timbers delivers across the Twin Cities metro, and our crew handles slope prep, erosion control, terracing, and planting — so you never have to mow that hill again.