Posted by & filed under Land, Swales.


Terraces have been used sustainably for centuries.
Why not make a down-scaled version for your garden?

One of the first things to consider in beginning to design a garden is where, exactly, it should be. I have to say that this step usually takes a secondary place in my mind to exciting images of plants and vegetables flourishing in glorious abundance; but unless you make a plan first, this flourishing could easily just as well become glorious chaos. Energy efficiency is a good one to remember here: how can you make the most effective garden space with the least amount of effort?

If the space you have available to you is not flat, this question may seem a tricky one. I have found that gently sloping gardens are ideal for swale-making and water-management (more on this in another article) but what if your space is more vertiginous than this? If the only potential space you have is a steep slope, will this cause a problem for your garden?

For answers, we can turn to one of many of the great ancient civilisations of our world. Terraced gardens have been implemented for many centuries by various cultures; from the impressively shimmering flooded rice paddies of South East Asia to the flowing steps of the mountains of North Africa and Spain, making the once uninhabitable slopes verdant and abundant in their elegant levelling.

These terraces have made it possible for entire civilisations to live in places where previously people found it difficult to settle. In more recent times, in the Austrian Alps, Sepp Holzer has used terracing with great success to create aquacultures and microclimates (see Sepp Holzer’s Permaculture, 2011) on his 45 hectare farm.

But terracing is by no means limited to such grand scales. You may not have 45 hectares or a civilisation to feed; but terracing is still a very viable option on any scale.

With these eight steps as a guideline, you can turn the problem of your steep garden or other space into (of course) a solution.

The steps below are the methods I used to make a roughly 2 metre x 1 metre squared terraced garden in a mountainside. The materials listed should be widely available in any wild or semi-wild space. However, if your terraced garden is closer to ‘civilisation’ – i.e. in a town or city – you may wish to consider using alternatives. For example, in place of flat rocks you can use recycled tiles or bricks. In many British and European towns these are commonplace in skips or rubbish dumps, so just look around!

Whatever you decide to use, make sure you experiment with what feels most comfortable to you. And, most importantly, enjoy.

Materials I used:

  • Four or five large sticks, at least 5cm in diameter and 2m long
  • Many small sticks (at least 50), around 1m long
  • Flat rocks of varying sizes
  • String
  • Various mulching materials:
    - Ash
    - Dry leaves
    - Fresh plant matter
    - Manure
    - Straw
    - Compost (small amount)

Tools I used:

  • Post hole digger – a heavy, 2m long sharp metal spike designed for the purpose
  • Pick axe
  • Shovel
  • Container for moving around organic material and earth

Step 1: Visioning

As mentioned above, the plan is the most important part of the process. Imagine what you want to grow in your garden, and what you want it to look like. Using these, walk around your site and decide where is the best place to put your terrace.

Some questions you may want to ask: which parts of the landscape can help you to implement your garden plan?

Where looks like a naturally great place for a terrace to evolve?

Since you will be making essentially a curved ‘dam’ to hold the earth in which you level out your terrace with, you might want to utilise already-existing shrubs as part of the walls of the dam. I did this by using two wormwood bushes (Artemisia spp.) as an integral part of the sides of the fence. The strong, gnarly branches and tenacious roots of these species make them ideal plants for helping to hold in earth, so it might be a good idea to check for these characteristics on the wild shrubs already present in the place you are planning your garden.

Next, mark out where you want the terrace to be. You can do this using your pick axe; dragging it loosely in an outline of where your proposed garden will be.

With this step, of course, you can go into as much or little detail as you want. You can plan your vision out on paper as well as on site, or even make it part of a grander garden plan. It’s up to you.

Step 2: Water on my mind

One factor which I find important to consider in planning any garden: How will you water the garden, and where does the water naturally come from?

The answer to this, if it is on a slope, is from above (you knew that already?).

And to prevent your beautiful terrace from washing away at the first rainfall, it is probably a good idea to incorporate a swale into your garden plan as well.


Terrace Bed

The swale does not need to be very deep or wide; simply enough to dissipate the flow of rainwater downwards to enrich the soil of the garden, rather than flowing over the top of it. The key thing to remember here is to ensure that your swale is on contour when you dig it. I did this by sight; if you wish to be more accurate you could construct an A-frame to help you (see Hemenway, 2009: Gaia’s Garden: A Guide to Home-Scale Permaculture. Chapter 5: Catching, Conserving and Using Water; sidebar: How to Make a Swale).

My swale was only about 20cm deep and wide but it was sufficient to keep the garden intact during three months of almost daily torrential rain.

Step 3: Preparing to catch the earth

What you want to end up doing is moving the earth from the higher part of the slope to the lower part, to even out in a more or less horizontal terrace. So before beginning this, you have to make the ‘dam’ to catch all of the earth you will be digging out.

Take your post digging tool and make holes at each corner of your marked garden by plunging the tool into the ground. You want the hole to be at least 1m deep so that your fence will be sturdy.

Next, take your long sticks and dig them into the holes to create a fence post at every corner, fixing them in place by piling earth on top. You can add small rocks as well to hold them in place.

The two fence posts at the top of the garden are purely to hold the string and thus make the curved wall of the fence, and do not need to be more than about 10cm high. Far more important are the two at the bottom corners, which should probably be least 1.5m high.

For extra sturdiness, you can add fence posts at other points in the outline too if there are not already handy bushes present.

Step 4: Making it human-friendly

At the bottom end of my garden I used the pick-axe to even out a little bit of the slope, to make a path (see plan).

I ended up extending the path to go through the middle of another garden and joining a different section of path at another point; thus fitting in with the wider, holistic plan of the area as a whole.

You can also reinforce it with small flat rocks to help keep the path from eroding and to make walking on it more pleasant.

However you decide to incorporate your path, it is a good idea to do something which makes it easier for you to walk through your garden.

Step 5: Weaving with wood

Now you can fill in the fence using the smaller sticks and string.

Wrap the string around the entire perimeter, making three or four different sections so that the result is a kind of flimsy fence. For this I used string made from plant fibres, which meant that over time the inflexible string loosened and I had to make it tighter. Using elastic string would probably avoid this extra work; so overall I feel the benefits of using of a non-biological resource here would outweigh the detrimental effects. The choice is always yours.

Once you have the outline of the fence you can weave the sticks into the string to create something which will actually hold earth. Push the sticks up under the first piece of string, over the next then under the next; etc – much in the same way as you would weave a basket or other item with willow.

You can push the sticks up as close as you need to each other in order to create a tight-knit outline. Again, think of what an effective basket would look like.

Step 6: Steady with the rocks

Once you have made a ‘basket’ out of the entire perimeter of your garden, you can use the flat rocks to fill in the fence from the inside, in order to ensure that the garden is stable.

Place the flat rocks (or tiles if you are using these) with their flat sides facing the fence, fitting together. It doesn’t matter if some rocks overlap; as long as you can cover pretty much the whole fence from the inside.

I did this step originally by balancing the rocks on top of each other and then filling in with earth once the whole inside of the fence was covered. You may find it easier to make a line of rocks around the bottom of the garden; then fill it in with earth. Then build another layer of rocks on top of the earth, then fill this in, and so on.

Either way, by making sure that every part of the fence is supported with rocks from the inside you are helping the garden to stay sturdy.

Step 7: Building up the soil

Now the garden is ready to have the soil filled in.

Carefully dig out the soil from the top part of the garden and move it to the ‘dam’ at the bottom, smoothing out the ground as you do so until the level is more or less horizontal.

Once you have done this, a great way to boost the growth of the plants which you will put in the garden is to build up the soil in layers of sheet mulch, making sure you spread the layers evenly to keep the garden horizontal.

You can use all kinds of organic material to make the sheet mulch; it does not really matter exactly what. Far more important is to bear in mind what kind of things will break down into the appropriate nutrients to be beneficial to your garden.

For me, one of the key aspects of building up soil is ensuring that the balance of carbon to nitrogen is roughly equal, and that there is a good amount of both.

So for carbon you can use dry plant matter such as twigs and dead leaves, sawdust, charcoal, straw (be careful with putting this close to the top; if there are grass seeds present they will take over your garden) or even paper (although it depends on how long you are planning to leave the garden to ‘cure’, as paper may not decompose quick enough to integrate with the rest of your soil).

For nitrogen you can use all kinds of green plant matter, but especially any nitrogen fixing plants (such as clover, alfalfa, vetch, beans, peas, fenugreek, etc). All kinds of manure are good too, but especially high in nitrogen are horse, donkey and chicken manure.

It’s good to also consider what else other than carbon and nitrogen is needed for a really tasty soil. Potassium is another key nutrient element; for which you can use crushed shells, seaweed, ash, or even, if you happen to have some, blood and bone meal.

After laying down every layer of mulch I gave it a good soaking; accelerating the decomposition process.

Step 8: Ready to Grow

Once all of your layers are in place you are ready to plant up your terrace garden. Before doing this I added a final top layer of previously-made compost, in which to plant my seedlings. The idea of this is that the new plants have nutrient-rich soil already around them, and by the time their roots get big enough to reach down through the mulch layers, these have decomposed enough to provide more nutrients.

Now you can step back, relax, and enjoy the newest manifestation of this ancient technique for helping the land to help us. And while you’re looking around – are there any other sloping, seemingly impossible-to-plant-in spaces around you?

References:

  1. Holzer, Sepp, 2011. Sepp Holzer’s Permaculture. Chelsea Green Publishing, Vermont.
  2. Hemenway, Toby, 2009. Gaia’s Garden: A Guide to Home-Scale Permaculture, Chapter 5: Catching, Conserving and Using Water. Chelsea Green Publishing, Vermont.

7 Responses to “Making a Terrace Garden”

  1. Seán

    Very interesting article – any chance of some photos to get a feel for what was involved? Thanks

    Reply
  2. TariqD

    Thank you, interesting article but really let down without any pix to illustrate. Any chance of adding any?

    Reply
  3. Ty Thompson

    I agree with the first two commenters…I’m having a hard time visualizing it without some photos or illustrations. At a minimum, a finished “after” photo, and preferably photos of each step.

    Reply
  4. miraji muganda

    Hi i would like to have some thing like that. in our Garden,but can we have a support us?

    Reply
    • Gordon

      It only looks steep because the photo has been rotated about 45 degrees. Have a look at the stems in the background. They seem to be growing on a very strange angle – or the site may not have much fall at all.

      I agree that more photos of the actual installation would be very useful. I have difficulty understand the string-posts-dam idea without seeing another sketch, or photos.

      In addition, some more detail would be useful. For instance, it would have been useful to note that the proposed 20x20cm swale at the top of the area (see sketch above) will work to protect the downhill terraces only as long as the infiltration rate in the swale exceeds the inflow rate from the catchment above the swale. In the rocky soil in the photo there may be very slow infiltration.

      It is also important to note that the steeper the slope the higher will be the walls, leading to possible instability issues, as well as meaning that more digging is required to per unit are of terrace created. On a 45 degree slope you need to dig a wall 1m high in order to create a terrace 1m wide.

      I think that for other than very small terraces a swale at the back of the terrace, at the foot of the wall, will have several advantages. This is known as Fanya Juu terracing (http://www.youtube.com/watch?feature=player_embedded&v=b9Z_wYJyBCE#t=41). It provides more soil for building the terraces, infiltration of excess rainfall rather than having it spill and erode the outer edge of the terrace, and mulch and silt build-up in the back-swale can easily be shovelled onto the swale above to improve soil quality.

      Reply
  5. Sheri Menelli

    I’m very excited about this article. It is something I really want to do on my own hill. I agree. Please, please, please post several more picture. Thank you so much – this is really valuable information!

    Reply

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