Top Tips For Landscaping A Sloped Yard in Australia

Properties on steep slopes make for unique houses and gardens. Though some find a sloped backyard challenging, the landscaping opportunities are well worth the effort. Homes on sloping blocks have many advantages, from amazing views through to long-term property value. With the right strategies, you can have a beautiful, low maintenance backyard on a sloped lot too. 

It might sound tedious to landscape a steep slope as there are many factors to consider, but the aesthetic possibilities are exciting too. Landscaping your sloped backyard doesn’t have to be difficult,  though getting assistance from professionals will make the process much easier. 

Using retaining walls, terracing, rip rap stabilisation and choosing plants that thrive on slopes are our top tips for landscaping on a steep slope. Although landscaping on a slope does have its challenges, following these tips will allow you to create a beautiful sloped backyard. 

If you’re building a new home on a slope, your builder can help connect you with the right contractors to landscape your yard to perfection. When landscaping an existing hillside property, you’ll need a specialised landscaping contractor who can assist with earthworks such as retaining walls. 

Sloping yards will require more investment in the design process upfront, but it’s worth all the effort once you see your sloping garden in full bloom.

Read on to learn more about the best options for sloped yards. 

What Are The Challenges Of Landscaping A Steep Slope?

Landscaping a steep slope can be rewarding when done properly, but there are a lot of factors to consider when starting the process. It’s not as simple as just planting what you like, the angle of the slope, and how it is affected by external factors, all add challenges to landscaping a steep slope. 

Erosion – Soil stability and erosion are easily the top problems when landscaping a hillside or a steep slope. Although soil that is mostly clay holds better than sandy soil, both still face the problem of erosion. Gravity and the angle of the land don’t allow water to seep through the ground. Instead, because of the steep slope, water courses down and erodes the topsoil.

A consequence of soil erosion on a steep slope is also the loss of nutrients in the soil. This means that the soil fertility is affected by the water running off, making the land not ideal for planting or gardening. Despite that, it is still possible to have a garden in your sloped backyard. You just have to pick the right vegetation.

Drainage – Drainage and irrigation are also something to consider when dealing with a steep slope. Is there a water source nearby? Does your lot have hilly terrain leading to water accumulation or flooding? How will you maintain or water your plants? It is best to get professional help to ensure that you won’t have drainage problems in the long run. For a new home build, your building company can help you make the right arrangements. 

Maintenance Accessibility – Maintenance access can also be a problem with landscaping on a steep slope. An elevation of 33% or 3:1 (thirty centimetres vertically for every ninety centimetres horizontally) can overturn a mower or a tractor. This is why some people try to plant low-maintenance vegetation, create built-in irrigation, or even create access paths or flat areas for maintaining their landscape. Getting a tractor or heavy equipment to work on steep slopes is usually what drives the cost of landscaping a hillside property higher.

You also have to be more creative in your landscaping and design ideas, considering maintenance, soil, and geographic location. For some, they see this as limiting their gardening choices; but for others, this is a welcome challenge.

What Do You Do With A Steep Sloped Backyard?

A steep sloped backyard may be difficult to work with, but it’s certainly worth the investment. The yard designs you can achieve with a sloped backyard are significantly more impressive than what you can do with a flat piece of land. 

Levelling the lot can simplify the process, but it’s also costly, so it’s worth considering alternatives that work with (rather than against) your yard’s terrain. 

Natural Landscaping – If you want to landscape your sloped backyard as naturally as possible, you have options with natural stones, cobbles, or boulders to help with terracing or rip rap stabilisation. You can also put in the mix some low-maintenance and drought-tolerant plants. With a good eye for design (while still considering drainage and irrigation), you can come up with a beautiful steep slope garden.

Gardening – If you’re looking to use your sloped backyard for a unique vegetable garden, that’s possible. You may use heat-treated pallets, raised beds, terraces, or contour rows to plant your vegetables. Then, pick plants that are deep-rooted or aren’t top heavy. Some recommendations are lettuce, spinach, chard, rocket, corn, squash, and cabbage. That said, you still have to consider your geographic location and the microclimate of your local region.

Installing A Water Feature – Nothing calls for a water feature quite like a beautiful, natural slope. Using the natural lay of the land, you can install a variety of water features that will create natural soundscapes, perfect for relaxing nearby. A water feature on a sloped piece of land is also a great way to add property value to a home, and add to resale value. 

Terracing – To help deal with the problems in earth load or pressure, consider terracing and/or building retaining walls. They can break up the slope and distribute the earth load. Rip rap also helps, as it functions similarly to retaining walls. It’s best to have engineers help you here since there are some standards that must be followed, especially for high retaining walls.

If you want to make your sloped backyard a functional space, your best option is to terrace and/or use retaining walls to create decks, access areas, and/or footpaths. The flat areas can be your entertaining spaces with a superb view. Footpaths can help you with maintaining your garden more easily.

Read on to learn about the best options for stabilising a sloped backyard. 

How Do You Stabilise A Steep Slope?

There are several options that work well to stabilise steeply sloped yards: retaining walls and terraces, rip rap stabilisation and planting. 

Retaining Walls

Building retaining walls is one way to stabilise a steeply sloped garden. A retaining wall is essentially a structure that holds back the soil of a slope or a structure that resists lateral load caused by the pressure of the earth.

The most common retaining walls in Australia are:

• Gravity retaining walls, which have a wide base and lean backwards slightly;
• Anchored retaining walls, which are straight and thin walls that are anchored by cables.

The cables link the top and bottom of the wall, which are buried in concrete;

• Sheet pile retaining walls, which also use cables but are ideal for softer soil; and
• Cantilever or reinforced retaining walls, which have a T- or L-shaped for greater support.

Retaining walls can be made from various materials. What material you choose to build your retaining wall from depends on what characteristics you value, and what you have access to.

Sleeper Walls – Sleeper walls made of timber or concrete can be moulded into various designs and are generally cost-effective. However, they cannot be waterproofed effectively.

Stone Walls – Broad-based materials like gabion walls, boulders, and cut stone (sandstone) are strong and stable, but they cannot be waterproofed effectively. The gaps between the stones may also result in unpredictable performance.

Concrete Walls – Reinforced concrete block walls are made of concrete masonry hollow blocks with reinforced steel. They are flexible in terms of aesthetics and can be waterproofed effectively. They can be costly, however.

Link Block Walls – Similar to reinforced concrete block walls, link block walls are also available in a multitude of patterns. They can be tricky to install, so make sure you get an experienced sloping block builder to assist. 

Retaining walls over 800 mm require licensed builders (Australian Standard, AS4678—Earth Retaining Structures). However, even those under 800 mm require tough work as good-quality retaining walls require careful consideration of various elements, including drainage, backfill, depth of posts, footings, drain pipes, geotextiles, waterproofing, and, of course, design. 

Still, whether you’re hiring a builder or doing a DIY for your retaining walls, make sure you check with your local council for development restrictions. Other considerations when building a retaining wall are other walls nearby, pipelines or trenches at the base of the wall, moisture levels, salt exposure, soil type, the slope of the ground above and below the wall, surcharge loads above the wall such as other buildings or vehicles, and even the wind, earthquake, and hydrostatic loads.

Terraces

Terracing is another common way to stabilise a steep slope. To terrace a slope means to create flat areas on a slope or hillside in order to break the straight and rapid water runoff on your sloping block. 

Creating terraces is a great idea to landscape your hillside property, especially if you like alfresco entertainment or have a great view that practically demands a viewing deck. Terraces usually require retaining walls at the top and/or bottom of the flat area. 

Three options to terrace your block are:

Infilling or creating a retaining wall at the bottom or lower point of the slope
• Excavating or creating a retaining wall at the top or higher point of the slope, creating a structure to hold back the remaining hill
• Using both infilling and excavating or creating retaining walls at the top and bottom of your terrace

Decorating a terrace is just as important as what you choose to grow in it. It can add a splash of colour or a natural tone to your garden. 

You may decorate your terraces by:

• Planting cover crops to keep the soil from eroding and even compacting soil and contributing to its nutrients
• Planting perennial fruit trees and letting them take root to also hold the soil
• Using organic and sustainable materials like logs, brushes, and wood to secure the terrace stages or
• Building an alfresco entertainment deck or bonfire space.

Get creative with it! Talk to your home builder about other options, especially if you want to make the terraces a functional space. If your builder specialises in building on odd-shaped blocks, they’re bound to have some clever strategies to make the most of outdoor space. 

Rip Rap Slope Stabilisation

Rip rap refers to a layer or wall made of stone, boulders, or cobbles meant to stabilise soil or protect sloped land from eroding as rip rap reduces water velocity.

 Rip rap slope stabilisation requires strategically placing angular stones to form an interlocking structure quite similar to a retaining wall. Rip rap is okay to use for slopes with less than 66% angle; higher than that, retaining walls are the better option.

Planting 

Planting or vegetation is another way to stabilise a steep slope. It is ideal for slopes with less than 50% angle or in combination with other techniques, like terracing.

The logic behind planting as a slope stabilisation technique stems from the fact that, from above, the stems, leaves, and shade act as a buffer to rain and water. Plants slow down surface flow so that water doesn’t simply run off downstream but actually seeps through the soil. Underground, the roots also act as anchors and reduce soil compaction.

Can You Put A Garden On A Sloped Yard? 

Yes, a garden is a great addition to any sloped yard. You’re not limited to rocks and natural stones. In fact, planting or vegetation is one way to stabilise sloped land, so it will not only bear fruit, but also help with fast water runoff.

Plants still grow in a sloping garden, but you have to strategically pick what you put in your sloped backyard. Here are some tips to help you landscape your sloping garden.

Choose Hardy, Low Maintenance Plants – This is especially important if you want your sloped backyard to be self-sustaining. If you’re not planning to cut your steep slope with access paths, some of your options are shrubs, evergreen, hosta, fern, hypertufa, olive trees, Ficus hilli Flash, geranium, fountain grass, juniper, and lilac.

Pick Native Plants To Reduce Maintenance – They are also sustainable and environmentally friendly options.

Consider Drought-Resistant Plants – They can survive fast water runoff and arid weather, not to mention they’re also low-maintenance. Some options are sedum (stonecrop), barrenwort, creeping thyme, and sea lavender.

Raise Your Vegetable Gardens – If you’re planning to make your sloped backyard a vegetable garden, use raised beds, terraces, or contour rows.

Use Pallets For Stabilisation – The pallets act like terraces for plants. They slow down water runoff, allowing water to seep through and water your vegetation. The pallets also help your plants get established faster.

Consider The Angle Of The Slope – Depending on where you are geographically located, put your moisture-loving plants at the bottom and those that can survive hotter and drier climates at the top.

Pick Plants That Grow Well In Crevices – You may use crevice-loving plants like candytuft, rockcress, thyme, hens and chicks, near retaining walls or rip raps. 

Use Mulch To Keep The Weeds Out – First, lay wet newspaper, burlap cloth, or jute netting over your slope. Then, add mulch. Pack the mulch approximately 100 mm deep. Apart from keeping the weeds out, using mulch can also help retain moisture in your sloping garden and keep the plant roots warm in winter.

Gorilla hair mulch is a good option because its fibrous texture makes the mulch intertwine and stick together well. Another recommended alternative is shredded hardwood mulch as it sticks well to newspaper or burlap.

See How A Rock Garden Can Improve Your Slope – Large natural rocks buried a third of the way into the soil can stabilise and retain the soil in your sloped backyard. There are also rock-loving plants like sedum (stonecrop) and ornamental grasses, which are low-maintenance. You can also have other options with creeping juniper, sweet woodruff, ajuga, rockcress, candytuft, and periwinkle, to name a few.

Consider Building Stairs Or Terraces – Stairs can give you access to help maintain your garden. Terraces, on the other hand, can make each garden patch more manageable. These also contribute to design aesthetics and make your backyard a wonderful place to explore. 

What Is Good To Plant On A Slope In Australia?

It is good to consider native plants to your geographical location when landscaping on a slope. The plants will not only be low-maintenance but also environmentally friendly. Here are some good plants to landscape your garden in Australia.

Good plants for sloped gardens include:

• Bluebell Creeper shrub
• Bleeding Heart
• Sarsaparilla
• Dwarf Forsythia
• Acacias
• Spinifex grasses
• Burning bush

The best grasses for sloped lawns include:

• Fescue grass
• Kikuyu grass
• Redgrass and Bluegrass
• Bahia grass
• Buffalo grass
• Wallaby grass
• Kangaroo grass 

Some native Australian options for ground cover on slopes are:

• Rock Daisy
• Beach Strawberry
• Native Violet
• Cotoneaster
• Jug Flower
• Creeping Myoporum
• Dwarf Coyote Bush

If in doubt about which plant combinations to put in your sloped backyard, don’t hesitate to seek help from professional landscapers or even your home builder. Though you have a list of low-maintenance or drought-tolerant plants at your disposal here, remember that there are still other considerations when landscaping a sloping garden.

How Do You Grow Grass On A Sloped Yard?

Growing grass on a sloped yard can be tricky at first, as rain and heavy water runoff can wash away the seeds. Regardless, it’s definitely doable to grow grass on a sloped yard.

Step 1. Choose A Grass Species That Will Grow On A Slope 

Choose those that are deep-rooted and establish rapidly to avoid the erosion problem as early as possible. Some of your options are:

• Fescue grass
• Kikuyu grass
• Bahia grass
• Kangaroo grass
• Weeping grass
• Redgrass

Step 2. Prepare Your Soil 

Then prepare and condition your soil. Use fertiliser and add lime (if needed). Depending on the type of grass you choose and the type of soil you have. If you aren’t sure what type of soil you have, or what you need to add for the grass you are planting, it’s always best to have a chat with your local landscaping professional.

Step 3. Mix Your Grass Seeds With Top Soil

Some recommend a 2:1 seed to soil ratio. Compact them so that the seeds don’t wash away before they get established. Once you have your seeds in, cover your land with burlap, mesh fabric, or cheesecloth.

Step 4. Redirect Water While You Are Planting

Once all that is set, it’s best to redirect water runoff by building a temporary wall at the top edge of where your seeded area is. You may remove this once the grass has established itself. Using sod can make the grass establish itself quicker, so you may want to consider that as well.

Step 5. Water Your New Garden

Water your area lightly and rake as needed to lightly cover the seed with soil and ensure that birds do not eat the seeds. Another way to protect your seeds is to cover your seeded area with mulch, straw, or wheat. Once your grass grows, be sure to properly maintain it for a thriving lawn. 


Do I Need A Retaining Wall If I Have A Slope On My Property?

You don’t necessarily need a retaining wall if you have a slope on your property. Reasons you may want a retaining wall include creating a flat area for growing plants, water drainage issue, concerns about erosion, or if the slope is unstable. Other than those reasons, building a retaining wall can also be an aesthetic choice.

Do I Need To Know The Angle Of My Sloped Garden?

It is ideal to know the angle of your sloped yard if you’re planning to landscape or perform any earthworks. Design choices such as terracing or retaining walls will require a detailed survey of the land, as any changes will need to be structurally sound. This is one of the first steps a professional will take before making design choices around your backyard landscaping. 

Planning to Build on a Sloping Lot? 

If you’re planning your dream home on a sloped block, you’ll get the best results when working with a specialist builder. Making the most of a steep property is all in the design, so partnering with a custom home builder makes all the difference. 

If you’re building a home in the Perth region, Central Avenue Homes are the sloping lot experts who can offer you the most personalised experience. From design to handover, you’ll benefit from our decades of experiences developing Perth properties. 

Learn more about sloping lot home builds in Perth or talk to Central Avenue Homes for more information.

Disclaimer:

This article is published in good faith and for general informational purposes only. It does not take into consideration your individual circumstances and does not constitute an estimate for any specific project. Central Avenue Homes does not make any warranties about the ongoing completeness, reliability and accuracy of this information. Construction costs and other financial details vary and you should always seek a specific quote.

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