Working with a steep hill landscaping project can feel intimidating at first. The slopes and angles present unique challenges, but they also offer incredible opportunities for a stunning and dynamic garden. With the right approach, you can turn that difficult terrain into your property’s most captivating feature.
Steep Hill Landscaping
The key to success on a slope is working with the land, not against it. Your primary goals are to control erosion, create safe access, and choose plants that will thrive in these conditions. Rushing in without a plan is the biggest mistake you can make.
Start With a Solid Assessment and Plan
Before you buy a single plant or stone, spend time observing your hill. Walk the area at different times of day to see how sun and shade move across it. Notice where water pools or runs off quickly during rain.
- Measure the Slope: A simple way is the “rise over run” method. Drive a stake at the top, one at the bottom, and tie a string level between them. The vertical distance divided by the horizontal distance gives you the slope grade.
- Check Soil Type: Dig a few test holes. Is it sandy and loose, or heavy clay? Sandy soil erodes faster but drains well. Clay holds water but can become slippery.
- Identify Problem Areas: Look for existing erosion gullies, bare spots, or unstable sections. These will need immediate attention in your design.
Sketch a rough map. Decide where paths or stairs might go, and where flat terraces could be created. This planning stage saves you massive effort later.
Erosion Control: Your First and Most Important Job
Without proper erosion control, your hard work can literally wash away. You need to hold the soil in place from day one.
- Use Erosion Control Blankets or Netting: These biodegradable fabrics hold soil on new slopes until plants establish. They are a crucial first step after grading.
- Plant Groundcovers Immediately: Choose fast-spreading, fibrous-rooted plants. Creeping juniper, ivy, or periwinkle (vinca minor) are excellent for quick coverage.
- Install Retaining Walls for Severe Slopes: For very steep sections, low retaining walls made of stone, timber, or interlocking blocks can create level planting areas. Always ensure proper drainage behind the wall.
Remember, the root systems of plants are your best long-term defense against erosion. The more you have, the more stable your hill will become.
Building Safe and Functional Access
You need to be able to maintain your hillside garden safely. A simple, well-built path or stair system is essential.
- Plan the Route: Chart the most natural, gently zigzagging path up the slope. Avoid going straight up and down.
- Build Stable Steps: Use pressure-treated timber, stone, or concrete pavers. Bury the riser of each step slightly into the hillside for stability. Make sure treads are deep and even.
- Add Secure Railings: For any steep or long staircase, a sturdy railing is a must for safety, especially in wet weather.
- Consider a Gravel Path: For a less formal route, a wide gravel path with railroad tie steps can be effective and blend naturally.
Non-slip surfaces are crucial. Avoid smooth materials like polished stone on steps, as they become slick when wet.
Choosing the Right Plants for the Slope
Plant selection can make or break your steep hill landscaping project. The right plants will anchor the soil and reduce maintenance.
Best Plant Types for Hillsides
- Deep-Rooted Shrubs: Forsythia, rugosa roses, and broom have deep, strong roots that bind soil. They provide structure and year-round interest.
- Ornamental Grasses: Switchgrass, fountain grass, and blue fescue have dense, fibrous root mats. They sway beautifully in the wind and are very drought-tolerant.
- Native Perennials: Plants like coneflower, black-eyed Susan, and coreopsis are adapted to local conditions. They often have tough root systems and require less water.
- Low-Growing Groundcovers: For large areas, sedum, thyme, and creeping phlox offer colorful, dense coverage that chokes out weeds.
Avoid plants with brittle stems or shallow root balls. They won’t withstand the water runoff and may simply topple over.
Terracing: Creating Usable Flat Spaces
Terracing breaks a long slope into a series of level “steps.” This is one of the most effective methods for managing steep hill landscaping. It creates planting beds, reduces erosion, and makes the area usable.
- Mark Your Terraces: Use stakes and string to outline where each flat terrace will be. They don’t all need to be the same width.
- Build the Support: For each terrace, you’ll need a small retaining wall at the downhill edge. Use stone, timber, or concrete blocks.
- Backfill and Level: Behind the wall, add drainage gravel, then fill with quality topsoil. Level the terrace carefully.
- Plant Each Tier: Treat each terrace like a separate garden bed. You can even use different themes or color schemes for each level.
Terracing requires more initial labor, but it dramatically simplifies long-term care and watering. Each flat area holds moisture much better than a slope would.
Watering and Irrigation Solutions
Watering a slope is tricky. Water tends to run off before it soaks in, wasting resources and leaving plants thirsty.
- Soaker Hoses or Drip Lines: Run these along the contour of the hill, not up and down. They deliver water slowly directly to the root zone.
- Create Small Basins: When planting, build a small soil berm on the downhill side of each plant. This creates a mini-terrace that catches water.
- Water Deeply and Infrequently: This encourages roots to grow deep, searching for moisture. Deep roots stabilize plants better and make them more drought-resistant.
- Consider Smart Irrigation: A timer with a drip system ensures your hill gets water consistently, even if you’re away. Look for systems with a rain delay sensor.
Mulch is also your friend here. A 2-3 inch layer of shredded bark or wood chips helps retain soil moisture and prevents weed seeds from taking hold on bare soil.
Long-Term Maintenance Tips
A well-designed hillside garden should become easier to care for over time. Focus on these practices to keep it healthy.
- Weed Regularly: Weeds compete with your plants for water and nutrients. Catch them early before they establish deep roots.
- Refresh Mulch Annually: As organic mulch breaks down, it adds nutrients to the soil. Topping it up each spring maintains its benefits.
- Prune for Health and Safety: Keep paths and stairs clear of overgrowth. Prune shrubs to encourage bushy growth, which covers more ground.
- Inspect After Heavy Rains: After a major storm, walk the hill. Look for new erosion spots, clogged drainage, or damaged plants that need replacing.
Don’t be discouraged if a plant or two fails. It’s a learning process. Replace it with something different that might be better suited to that specific spot on the hill.
FAQ: Your Steep Hill Landscaping Questions
What is the cheapest way to landscape a steep hill?
The most cost-effective method is to plant a mix of fast-growing, deep-rooted groundcovers and native grasses from seed or small plugs. Using natural materials like fallen branches for temporary erosion check dams can also help on a budget.
How do you mow a steep hill?
For safety, it’s best to avoid mowing a steep slope altogether. Use a string trimmer for necessary trimming, or better yet, design your planting so that no mowing is needed. If you must mow, always go across the slope horizontally, never up and down, and use a walk-behind mower with excellent traction.
Can you put a retaining wall on a steep slope?
Yes, but it’s critical to get the design right. For slopes over a certain height or angle, you may need a tiered series of shorter walls. Drainage behind the wall is non-negotiable. For tall walls, consulting a professional landscaper or engineer is highly recommended to ensure stability.
What are good trees for a hillside?
Choose trees with strong, spreading root systems. Oaks, maples, and pines are generally good choices. Avoid trees with brittle wood or shallow roots, like some willows or poplars, which could become unstable. Always plant them securely, staking if necessary when young.
Starting a steep hill landscaping project is a commitment, but the rewards are immense. You’ll create a beautiful, living tapestry that protects your property and provides endless interest. Take your time, focus on stabilizing the soil first, and choose plants wisely. Your challenging terrain will soon become your garden’s greatest asset.