Landscaping in Difficult Terrain

Got a sloping block, awkward corner, or challenging piece of land that feels impossible to landscape? In this episode, Keith explains why difficult terrain can become one of a garden’s greatest assets. From creating garden rooms and pathways to making the most of views and natural features, this episode is packed with ideas to help gardeners see opportunities where they once saw obstacles.

Plants recommended in this episode

• Callistemon spp. — Bottlebrush
• Acacia spp. — Wattle
• Eucalyptus spp. — Eucalypt

Products & Tools recommended in this episode

• Geofabric
• Jute erosion-control matting
• Weed Gunnel
• F.D Ryan's Broadfork

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Transcript

SPEAKER_01 0:01

Hello, I'm Elizabeth, an obsessive backyard gardener, who might be able to offer you a couple of tips.

SPEAKER_02 0:07

And I'm Keith, a landscape consultant, and I'm also passionate about gardening.

SPEAKER_01 0:12

The one thing we both have in common is muddy boots. On today's podcast, we're going to tackle a challenge that many gardeners face: the sloping block. Whether your garden gently falls away, has steep embankments, awkward angles, or multiple levels, these sites can often feel difficult to design, maintain, and plant. But with a little planning, those challenges can become some of your garden's greatest assets. Keith's going to tell us how he how we can work with the landscape. I'll do that a bit again. Keith is going to tell us how we can work with the landscape rather than against it, and how to create a practical, beautiful garden on a block that isn't flat. So, Keith, you are currently working on a design, I know you've told me that, that design that includes some fairly steep slopes, which we'll talk about through the podcast. When you first visit a garden with significant slopes or awkward angles, what are the things that you assess to start with?

SPEAKER_02 1:10

You look at the opportunities that you can create on a sloping block of land. And that is just mind-blowing when I look at a job like that and um I just see the opportunities and things that you can create there. So that you can create so much more interest on a on a sloping block of land, whether it's just a residential job or whether it's a big job. And as as you mentioned, I have a very, very large job, which is probably four acres, on a r rather steep slope. And to give people an idea of how s how steep this is, um the the the the owner, my client, took me down there in a in a four-wheel drive. She got bogged. No, in in a four-wheel drive, but she only had it in two two-wheel drive. And we went down the the actual slope and she turned around and we couldn't get up. So she had to put into four-wheel drive in order to get us up and out of that block. So that's how steep it was. You wouldn't get out in a normal car. The other way to think about it is that this is that we're talking four acres, and and if we can imagine from the top of the of the block or the top of the slope, to the bottom of the slope, which is about 140 metres, there is a fall of 17 metres.

SPEAKER_01 2:34

Who's good at their mass? But anyway, that sounds stupid.

SPEAKER_02 2:37

Well that's a that is that is a slope of about 32.5%. Right. So it's it is really, really steep angle. Yeah, yeah. And she just she just looked at her, looked at that and looked at me and she said, Well, what what can I do with this land? I mean, I don't want to keep it as a as a paddock to feed, you know, sheep and you know, cows on. What can I do with it?

SPEAKER_01 2:57

You know, that's what I was going to ask. That's what I was going to ask. Where what do what are the biggest mistakes that owners, before they go to someone like you, can make when they want to landscape a hilly block? Well, if they do it themselves. Yeah.

SPEAKER_02 3:09

What they do is they don't look at the opportunities that you can create there. They look at that and say, well, it's a s it's a slope. How the hell can I traverse you know up and down this slope? Um and and and just on this job, the the one of the greatest features of of this this site was down the very bottom in the left-hand corner was a beautiful black dam.

SPEAKER_01 3:32

Black dam.

SPEAKER_02 3:32

Well, the water was black. It was almost with the sun that light was coming through the trees that that were over it. It was like a mirror.

SPEAKER_00 3:40

Wow.

SPEAKER_02 3:41

Um, and the lady, um the client told me that um they bought this property during the big bushfires. And um Where is it? It's up in Upper Packenham this job.

SPEAKER_01 3:51

In Victoria, yes.

SPEAKER_02 3:52

Um so it's in Victoria. So up in the hills in Upper Packenham. Uh and they bought they bought the property during the big bushfires and the drought that we had prior to that, and the dam was still full, so it's spring fed. So, you know, so and and that is just sitting lost down in the in the bottom of this of this paddock.

SPEAKER_01 4:11

Ah, you saw the opportunity.

SPEAKER_02 4:12

So you look at that and you say, My goodness, where is the opportunity in that? You know, so so that's so that's the way that I look at it.

SPEAKER_01 4:20

You know, it's it's always better to use the better to work with the existing slope rather than trying to flatten it. I mean you couldn't have flattened that one.

SPEAKER_02 4:26

I know you never flatten it.

SPEAKER_01 4:27

But it's always better to do that. It doesn't matter what, even if it's a smaller slope, it's better to keep it as it is and to make and make add interest to it.

SPEAKER_02 4:35

Yeah, yeah, yeah. So so the way that the way that I uh and I explained to her while we were sitting, you know, trying to get this thing into four-wheel drive to get out of there, and she said, Well, what can I do with this? This is you know, this is just it's just a waste of land. And I said, No, it's not. I said, What we what I would do with this land, if you allow me, is we would put pathways that cross on a on a slight angle from one side, and then drop down and go to the other side, and then drop down and go to the other side, and then back, and then eventually end up down at the dam.

SPEAKER_01 5:09

So it's it becomes a lovely place to walk, and you'll have garden beds all the through the top.

SPEAKER_02 5:14

So the garden beds, so so so where these pathways are going to be cut through the slope, we need to retain the walls, and you can do that in a number of ways. Um one of the the if it's a if it's a fairly hard, steep um cut that you put in there, you can you could use um treated pine sleepers or concrete sleepers for longevity. Or um having spoken with um our favourite landscaper Matt Phillips from Morning Side Lands. From Morningside Landscapes, um he said to me, Well, why don't we have a look at using gabians, which are actually wire baskets. Yes, they fill with rocks that you that are all joined together and you fill these with rocks. Um and and they have a what's called a geofabric fabric that goes behind them. So you make your cut first, you cut, and then where your pathway is, you push it out, so you take a cut and you spread out that dirt across. So we've got these pathways will be over two meters wide, so you'll get a you'll get an all-terrain vehicle down through that.

SPEAKER_01 6:15

Fantastic.

SPEAKER_02 6:16

So this is another thing. So it doesn't matter how old you are, you can still drive round this and utilize this space. So we to retain that big cut, we're going to use these gabians which are made out of out of a um a wire, but it's not a taut wire, it's a wire that will actually flex a little bit, um, and will they be filled with rocks, but they'll have a geofabric behind them and underneath them, which means that the water as it comes down the slope will filter through the geofabric, through the rocks, and then just gently out onto the pathway, which will all be a crushed rock filled with a screening on the top of the on top of that.

SPEAKER_01 6:55

Yeah, yeah, okay. Um some of the questions are going out the door because you're just talking about this. How can I guess this is gonna work? How can terraces or retaining walls help make a difficult block more usable?

SPEAKER_02 7:06

Well, what they're doing is is they're providing flat areas. So um this this means that you you you're actually terracing areas. So by by by cutting into the bank and then filling it out and then putting a retaining wall, which is a terrace wall, across that that cut, you've then provided a flat space. So regardless of whether you whether in this in this big job where you're looking at long pathways that go uh travel across the the size of the block, if you just terraced areas in a smaller situation, you can then have little little walkways that go down from one end to the other on these terraced areas. And then you can infill those in between them with garden beds, with with trees and with shrubs and all the rest. So we've done all that on this particular, we're going to be doing all this on this big job.

SPEAKER_01 7:55

Yep, yep. Uh you mentioned the Gabian walls and you've uh you've mentioned treated pine. What should people consider other than those when choosing materials for retaining walls and the pathways as well?

SPEAKER_02 8:04

And pathways, yeah. You can the other thing that that that I've specified on this job, in between the actual um pathways themselves, so the garden mid areas, we're going to be using uh an erosion control material, and there's a couple of options there. The one that I've that I've specified on this job is is going to be either a jute that is then pegged and then planted into that jute, or they can use a weed gunnel, which is which is pegged. But up the top where the actual uh you actually start, you actually do what's called an anchoring. So you dig a trench along the pathway and you push the jute up over it and under it, and then you backfill that. So that becomes an anchor, and then that is then pegged with landscape pegs all the way through. So it holds that bank while those plants are establishing themselves within that soil.

SPEAKER_00 8:56

Yep, yep, yep. Okay.

SPEAKER_02 8:57

So that's one way of one way of of um looking at the slopes.

SPEAKER_01 9:02

And but but what other materials should we be using with pathways and things like that?

SPEAKER_02 9:05

What are you using for your pathways for well the pathways are going to be they're gonna be because it's gonna be a cut and and that where the cut is, this the soil is going to be spread across as a fill, so it's a cut and fill, then we're gonna be putting down a um a crushed rock base, and then on top of the crushed rock base we're gonna be putting screenings. So it'll just be loose screenings. Okay. But that allows them allows any water to run through that and and and just move through in a gentle fashion.

SPEAKER_00 9:31

Okay, okay.

SPEAKER_02 9:32

Um give you an idea. Um at our place, for instance, here in Mount Eliza, um we've got a we've just got a crushed rock driveway. And I had granitic sand down on that, but when you we get enormous amounts of rain, the rain will will wash down over the hard surface and then hit the hit the crushed rock driveway, and it'll create rivulets. Yes. Really rip it out. But in order to stop that from happening, if you just put in just a you know, even 50 mil over the top of that of of um a screening, so uh a 20 mil screening, as the water goes through, it's got to work its way through all those screenings, so it can't rip into that and cause those that that erosion.

SPEAKER_01 10:15

Is there an option to put a bit of concrete into the with the like a mix of concrete into the um into the into the granitic sandwich?

SPEAKER_02 10:22

Yeah, and that's called stabilizing. That's called and you can use that with a stabilized crushed rock, for instance, to do that. Okay. Uh and that's what a lot more councils should be doing in their own car parks that are not bitumized, is putting in stabilized crossed uh crushed rock, which has got a cement mix through it. That's okay, but then what you're also doing is is providing um a runway for that water because it hasn't got anywhere to go except on that hard surface. But if you put little screenings, they become little boulders where it it just slows down that that that water flow and allows it to release itself easily at the very end, which is normally into the gutter.

SPEAKER_01 10:59

Okay. Okay, so that was what I was going to ask next is about drainage. So what about drainage is obviously incredibly important when it comes to these slopes?

SPEAKER_02 11:06

Yeah. So so the the gabians themselves will become that drainage um for the for that. But because these gabions are uh and I think they're about $140 each unfilled. Oh yeah, and then you've got to get the rock and then you've got to get the rock to fill them, um, that starts to become quite expensive. So the options then become that you you can put in um put in in in a a a gutter at the at the where you make the cut, you dig a you dig a trench and you fill that up with rock. And because it that that trench is running away on a slope, it you just direct that water down out, not across.

SPEAKER_01 11:44

Yep, okay, okay. Um what are some signs that drainage problems need to be addressed before any landscaping begins?

SPEAKER_02 11:51

Well, you need to look at at just the amount of water and where water's actually going on a site.

SPEAKER_01 11:56

How did you notice that on this job?

SPEAKER_02 11:58

You well, you look you look at it, you look at a job and you say, well, okay, well, which way is the slope running? Is it going off to one side of the block or is it going continually down the slope of the block? And you look at it that way, you say, okay, well, I can put a cutoff drain across the very, very top, and then I've got to redirect that that that cut off drain somehow else. So you could put a big cutoff drain across the top with with um swales, what are called swales, um, and that what that does is is that a swale is is is a horizontal drain that you can actually put uh trees in, plant trees into.

SPEAKER_00 12:32

Yeah.

SPEAKER_02 12:33

That the water hits that swale and and has to fill that swale up and then slowly percolate through the soil profile. So there's another great.

SPEAKER_01 12:42

Yeah, as it goes down the hill. Exactly. Okay. Are there particular plants that are especially well suited to holding soil on banks and slopes?

SPEAKER_02 12:49

Yeah, you you're looking for you're looking for various plants that that have got different root structures. So if you think about um with this particular job, I'm using a lot of a lot a mix of a lot of native plants, um things like calistamens and um acacias, for instance, and certain types of of eucalypts are going into this job that have all got root stabilizing um qualities and properties about their style. So that's that's going to happen all the way through. And then to break up that look, you can put in exotic trees, for instance, that have got incredibly deep root systems that will help to anchor everything within that space. Okay. But with this job, for instance, um the way that I I'm I'm treating it is that is that you can look down the well, the first the first pathway that you walk down will have a canopy of trees. So there's trees of the same variety plant on on either side of the pathway that will form a canopy.

SPEAKER_00 13:46

Beautiful.

SPEAKER_02 13:46

And as you're looking down through that, yeah, you'll be looking across to another paddock in the distance. So I don't want to lose that view because that's sort of uh you know a real enticing look. So I've I've got low grasses down the very bit of like things like powers and um and and you know the just short, short, low-growing grasses that'll will help retain and further fil filter water and so forth. And then as you're walking your way down through the pathways to get to the very bottom, um, I've got lots of other different types of plants. So there's the opportunity that's created down there is is the is because we've got that dam down there, I'm I'm creating a rainforest around that particular dam.

SPEAKER_00 14:28

Beautiful.

SPEAKER_02 14:28

So there'll be all rainforest trees that that will grow in this environment down that down in that that very little bottom spot.

SPEAKER_01 14:34

Okay. Sounds lovely. We'll have to see, we'll have to go and visit it.

SPEAKER_02 14:36

One day we'll go down and have a look.

SPEAKER_01 14:38

What are some clever ways to turn an awkward angle or an unused corner into a feature on a block like that?

SPEAKER_02 14:44

Um rocks are a great opportunity. And we notice in your backyard where you where where we've got a we've got some rocks we can't get off. We can't move. Yes. So we turn those into a bit of a feature, you know, and that becomes a corner. Um, you know, that the the pathway moves around.

SPEAKER_00 14:59

Yeah.

SPEAKER_02 14:59

So you can do that with or you can you can use grasses, for instance.

SPEAKER_00 15:02

Okay.

SPEAKER_02 15:03

Um that that do the same sort of thing. Yeah. You know, so so y you know, it's it's your imagination, I guess, that is the is the limitation.

SPEAKER_01 15:12

And sounds like pathways are fairly important.

SPEAKER_02 15:14

Pathways are very important. And you know, we we we've spoken about this huge job that we've that I've I've done, which which is is complete and and and I'm presenting that very shortly to the clients. But the next job that I've I've got on the drawing board is a residential place up in Ringwood, which has got the same sort of sloping block.

unknown 15:32

Oh wow.

SPEAKER_02 15:33

Um, you know, so uh the existing site is is that they want to put an extension on the house. Um so there's excavation got to be taken, so soil and stuff's gonna be taken out of that, um, and there's existing pathways and things through it. So we're going to use gabians again in in certain situations because they've actually got on site there beautiful little retaining walls with rocks. So they can take those rocks out of those retaining walls and face up the Gabians. So you you you you you know you're keeping that same look, yeah, but just moving it.

SPEAKER_00 16:07

Yeah, yeah.

SPEAKER_02 16:08

And then they've got other other um retaining walls which are uh uh link walls. Uh they've got one at the top and one at the bottom. So we're gonna take the well the top one's gonna be destroyed anyway, so we're gonna keep those those concrete um pavers or concrete retaining blocks, and we're gonna put them down the bottom and build up the bottom one. You know, so so you know slopes just give you so much they they create so many possibilities. Yes, they but create so many possibilities and so many opportunities.

SPEAKER_01 16:38

Okay. What are some practical solutions for access for accessing garden beds on steep sites apart from pathways?

SPEAKER_02 16:45

Accessing them.

SPEAKER_01 16:46

Yeah, accessing them.

SPEAKER_02 16:48

Well, they don't know any other any other thing but a pathway.

unknown 16:52

Okay.

SPEAKER_02 16:52

You can you I mean, really in this in the ringwood job, for instance, the only way that we can act access the beds are gonna be quite thin then to be able to access them because you're otherwise you're walking on the water. Well, well, yeah, I mean if if you sort of think about the garden you've got here, there there are no edges to the garden, to the pathways except the plants. So they become the the the plants determine where your pathways are. So you can do that as well. But that this job in Ringwood, we're gonna be using um lots of steps, for instance. Um and they've currently got steps that that are quite dangerous, particularly for for our young kids and for for the elderly. So we're gonna be using a lot of bluestone, big bluestone slabs to create big, easy steppers that will go through.

SPEAKER_01 17:36

That's what you can put that through garden beds too, so you can access them more carefully. Yeah.

SPEAKER_02 17:39

And of course we're gonna be we're gonna be looking at utilising this the the slope of the land and traversing across it, you know, with pathways and with steps to get from one one height to the next height.

SPEAKER_01 17:50

Yeah, okay. I've just got so many questions. I'm trying to listen to what you're saying at the same time. Um, do sloping blocks create different growing conditions such as frost pockets or dry areas or wind exposure?

SPEAKER_02 18:01

Um they do, and and therefore you've got to really think about how you're going to manage that. And and by and by putting in canopy tree plants, you're you are you are pro you're you're providing microenvironments underneath those. Yeah. So that those those canopy trees will protect what you're planting in underneath that. And in this sort of a situation, you've got to you've got to plan ahead. So you've got to put in plants that are going to survive direct sunlight initially until those plants provide those canopies up through it. So yes, there yes, there is.

SPEAKER_01 18:33

How you mentioned the the paddock that you want with those canopy of trees, you want to make sure you can still see through to that paddock. What uh the question I have here is how can gardeners make the most of the views often often available from elevator blocks, apart from your idea of the canopy of trees and making sure the plants are low.

SPEAKER_02 18:48

Yeah. Um you you you can put in you can put in little uh passages, for instance, and I haven't done with this job because the there's there's two main two main features to this particular to this particular job, which I'll explain in a in a minute. But if if people wanted to particularly harvest a a view, then you would have view corridors created. So you might have trees to a point and then you have a gap so that you can look down through it. So you can create those sorts of things. Which is you know, which is a nice way of looking at it. But with this particular job, um uh the final destination is the the dam and the rainforest around it. But before you get to that particular point, because this this is this is a big block of land, what they still want to have down there is a place to burn branches and rubbish and stuff, you know. So I've I've I've got another area on the opposite side to the dam, which is about going to be about ten metres uh wide where they can actually have a bonfire in that that that area. So the trees around it are basically going to be um fire retardant trees. Um but there's an opportunity for them to have have a space like a fire pit.

SPEAKER_00 20:02

Fantastic.

SPEAKER_02 20:02

With uh with Gabian uh with the Gabian walls that are tiered, so that that so then that gives an opportunity that they can actually sit on um and and and look at the fire.

SPEAKER_01 20:12

Sounds beautiful.

SPEAKER_02 20:14

And it's uh how big is this particular this is about four acres, this this particular spot.

SPEAKER_01 20:18

Okay, okay. Can challenging sites actually offer design opportunities that flak flat blocks don't?

SPEAKER_02 20:25

Yep, for sure.

SPEAKER_01 20:26

I suppose everything you've just talked about. Exactly.

SPEAKER_02 20:29

So so you you create interest on on a sloping block of land, you know. As I said initially, you don't look at a slope and say to yourself, well, gee, I can't manage that, I can't utilise that. That's it's of no use to me. It's just a slope. So you've got to think about how you can how you can operate that slope, and that is, you know, by putting pathways across it that make you know the traversing nice and casual and easy.

SPEAKER_01 20:53

Amazing. Yep. And you were gonna say something about we're gonna tell you I'm gonna tell you about that later.

SPEAKER_02 20:58

That was that was about the the the two components on this particular job, which was the dam as the as the final destination, and you can walk all the way around the dam underneath the underneath the the the rainforest trees, and then of course up the other end was the other other destination, which was the fire pit. Yes. So that's that's that was what I was getting at. Okay so so it we it wasn't um it wasn't a job that was looking at where you where you just looked at the whole slope, it was a job of where you're creating gardens within those slopes. Garden rooms. Garden rooms, yes that you have to have to go past and walk down to you know to actually enjoy it.

SPEAKER_01 21:38

Well, that's a lot of information, and that sounds very interesting. So thank you so much for that. So if anyone out there has got a sloping block, hopefully you've picked up a lot of little tips and hints from Keith in regard to that. Obviously, a sloping or awkward block can certainly present challenges, but Keith has just told us it can also create opportunities for interesting design, better views, distinct garden spaces or rooms, and some great planting combinations. For any of you who may be dealing with some of these challenges, call Keith. We hope today's chat has given you the confidence to embrace the shape of your garden and not ignore it or think it's too hard, put in the too hard basket. So thanks for joining us on Muddy Boots and happy gardening on your slope. Bye.

unknown 22:18

Bye.

SPEAKER_01 22:19

Thank you for listening to Muddy Boots. For more information on today's podcast, please go to muddyboots.net.au and happy gardening.