How to Create Landscapes on Sloped Properties

Overcoming challenges in the mountains of Utah…

At Sunline, we’ve had the privilege to work on lots of spectacular properties, many of which are on mountainous or sloped terrain. While designing and building on properties with multiple elevations can be challenging, it can also be rewarding. 

The secret behind any great landscape is having a solid design. When dealing with uneven terrain, the design process always starts with a topographic site survey so we can understand the challenges we’ll be facing. On top of that, there are a number of factors that have to be taken into consideration to ensure a successful and functional landscape design.

How will we access the property?

One of the first things discussed in our pre-construction meetings is how we will access the property since this has a direct impact on the budget. We’ll enter from either the top or bottom, depending on the topography of the property and which route is safest and most convenient for our team and equipment. Access from the bottom of the property is preferable. 

And it’s a good idea to be kind to your neighbors… you never know when you’ll need to use their property for access!

Drainage and Erosion Control

Sloped landscapes are prone to water runoff and erosion, especially when you have loose soil from excavation during the construction phase. 

Drainage is critical when building any type of retaining wall or structure on sloped properties. If the wall is built on soil, improper drainage will cause hydrostatic pressure to build up behind it, bending the wall outwards and causing it to fail. 

At Sunline, what we typically do to prevent hydrostatic pressure from building up is either divert the water around the wall itself through channeling or — more practically — placing a gravel aggregate behind the wall with a perforated drain pipe at the bottom. Known as a French drain, this system helps the water percolate down into the soil instead of building up behind the wall.

Any kind of planting will also help stabilize the soil and prevent erosion, especially native grasses with a deep root base. Ground covers are also a great option. In addition to soil stabilization, they give you a spillover effect over the wall, which is quite attractive.

Soil, water management and irrigation

The type of soil you have will determine if soil amendment is necessary, but since it can vary greatly from one property to another, you’d have to complete a soil analysis to know the exact composition of your particular soil type. 

In Utah, you’ll find all types of soil, from sand to clay and everything in between. We typically amend the soil before planting by adding two to three inches of fresh topsoil to help establish the root base. 

But what’s more critical than your solid type is making sure your landscape is irrigated. Any type of spray irrigation is going to help the root systems establish themselves faster than putting your plants and seeds on bare soil and crossing your fingers. 

We design all of our landscapes with site-specific irrigation plans, typically using 12” rotor heads that spray that water as far as possible into the native landscape. How many heads we put into native zones comes down to your budget, but we always recommend having a few in these zones. All our irrigation systems are designed to be as efficient as possible.

Of course, your irrigation system should be connected to a smart controller. Smart controllers, such as Weathermatic, rely on data from weather stations, allowing you to program your sprinkler system so you get the water you need without wasting a single, precious drop.

Structural engineering

Code-wise, for any structure over four feet high, you’ll need the services of a structural engineer. While we don’t have any structural engineers in-house, we will reach out to trusted engineers to help you take care of the details. 

Here’s how it works. Once we have a general plan mocked up showing the various elevations, we’ll send it off to the engineer. They’ll look it over and draw you what is known as a detail, which contains instructions on how the various elements need to be built to satisfy code requirements and ensure your wall doesn’t fail and tumble down the slope! 

Fees for this service can range from $1,800 to 10k depending on the complexity of the project… but it’s necessary to protect your investment and we simply will not build without it.

Planting on a slope

On a particularly steep slope we’ll use a native seed mix to plant larger areas. To apply, we spray the seed — which looks like blue foam and is mixed in with fertilizer and weed suppressant — over the landscape. This is done for two consecutive seasons, once in the spring and again in the fall, for a total of 4 treatments. 

This helps the plants take root and become established and you end up with a pretty solid root base on top of the grade. 

The seed mix we use varies depending on where your property is located. Park City seed mix is going to be different from the seed mix used in the valley, but in general, any type of fescue is going to have a longer root system than other varieties. 

We’ve had great success in most locations with fescue, fountain grass and any variety of coreopsis.

Stormwater and runoff

We don’t have many issues with stormwater, so using permeable pavers, rain gardens or other stormwater management systems isn’t really necessary, although some people like to incorporate them into their landscapes for other reasons, such as water conservation, improving water quality and providing food and shelter for wildlife.

Coping with harsh weather 

Drought is usually an issue here in Utah, which is the second driest state in the country. We try to be drought conscious by picking the right plant material and choosing plants that don’t require a lot of water. This means being smart with our grass mixes, the kind of turf we’re installing and the variety of plants we recommend.  

Once again, where your property is located will have a direct impact on the plants in your landscape. In Park City, for example, extreme snow loads can take its toll on trees and shrubs, with lots of broken branches. This isn’t as much as a concern in the valley, so the plants we choose need to be heartier in harsher conditions.

Plant Selection

For the most part, choose plants that are well-suited to the slope's conditions, especially those with deep root systems to help with erosion control and stability. Opt for native or adapted plants that thrive in the local climate and can handle the slope's sunlight exposure, moisture levels, and wind conditions. 

Select a mix of groundcovers, shrubs, and trees to provide visual interest and prevent soil erosion. We can help make sure you get the right plants in the right place. Having a thorough knowledge of your plant material makes a big difference. 

We import a lot of plant material from Washington, Idaho, and Oregon, especially mature trees and specimen trees — and with our tree program, our designers even travel out of state to choose the best tree for your property!

Access and Safety

Because of all the different elevations, it’s important to evaluate all access points and pathways to ensure safe and convenient movement throughout the landscape. This involves Installing steps and handrails and using landscape lighting to light up paths and walkways. You might also consider using non-slip materials to prevent accidents.

Create a landscape without compromise

You can accomplish anything — even a pool — with proper engineering and right-sized budget. It all comes down to how much you’re willing to spend and how much engineering is needed.

By understanding and addressing the challenges faced when landscaping in the mountains of Utah, it’s possible to create a visually appealing landscape that provides ample space for your family while harmonizing with the natural surroundings.

At Sunline, we have experienced professionals on our team who can help navigate these challenges so you can create the landscape you’ve been dreaming of. Simply book a consultation and tell us about your project.