As seen in: Issue 51

A Guide To Terrace Gardening

Hitting the Slopes

When we saw the views before buying our house, we didn’t anticipate all the gardening challenges on a steep slope. The property ticked many sustainable living boxes: water tanks, solar panels, a shed, flat areas around the house, and an established orchard on the slope below. However, as we started to design the kitchen garden and work with the site, it became apparent that a sloping block can present MANY challenges!

We are working with the positives of a sloping property, like incredible views, sunlight all year, cooling breezes, multiple microclimates, and the opportunity to harvest water and free energy. The two biggest issues we have had to face are access and watering. The soil is clay on a rock base. So, while it is minerally rich and holds moisture well, digging is a nightmare! We have flat pads where the house and shed are, so lawn areas have trees, shrubs, and hedges.

We are using several strategies to tackle the access, create more flat functional zones for gardens and recreation, get water where needed, and prevent soil erosion. We aim to make the property easier to navigate and enhance its visual appeal by adding value and functionality.

Strategies for Sloping Blocks

  • Create terraces and retaining walls to increase flat usable areas.
  • Add steps for easy access.
  • Build raised garden beds into terraces or narrow, awkward areas.
  • Use swales to grow on contour, harvest water passively, and reduce erosion.
  • Use hay bales as temporary barriers to stop fruit from rolling down the hill while capturing moisture. They can also double as strawbale gardens.
  • Excavate and infill to create more usable space.
  • Consider mulching or an automatic mower if mowing is impractical or too dangerous.

How I Tackled My Terrace Garden for My Dream Space

Kitchen Garden Zone

Behind the shed, we inherited a flat area and a timber sleeper raised bed, our starting point for growing food. Adding more raised garden beds made sense as we couldn’t dig down. We opted for 2m x 1m DIY kits that were economical and took five minutes to assemble. They are aesthetically pleasing and narrow enough to fit in a tight space. I squeezed in a block of four and designed minimum-width paths so I could still access either side with a wheelbarrow for maintenance. This bought us an extra 8m2 of growing space. I also added a tiered stand with shelves and self-watering rectangular planters to take advantage of vertical space. These suit shallow-rooted salad greens, herbs, and flowers.

Meanwhile, I have a huge temporary container garden with plants that need new homes! I have set up a mini nursery at the base of the rock retaining wall between the house and the shed. It has easy access to water and provides shade relief during our long, hot summer. I will gradually transplant these ‘renters’ to permanent accommodation on the terraces below.

Raised garden bed

Top Terrace Perennial Garden Zone

Two narrow, weedy terraces were below the shed with rock retaining walls. I used two strategies to turn the weedy grass into a garden. Firstly, hand digging (call me crazy) all the worst weeds and grass out of the top terrace after rain. I got a great workout, and it was my first opportunity to work with the native clay soil. It was heavy, so I decided to sheet mulch most of the terrace to make the next stage of establishing healthy soil easier. Since we’d recently moved here, I had plenty of cardboard boxes to lay over the grass and smother it. I covered this with composted manure, minerals, and a thick layer of mulch. All the rain helped activate the cardboard breakdown into carbon. So, within a few months, I could establish a food garden quickly with fruit trees, support species, perennials, fruiting crops like tomatoes, eggplant, capsicum, and lots of herbs and flowers.

Perennial top terrace gardens

Perennial Top Garden Access

On this terrace, I only had room for a narrow pathway. I planted on both sides, limited by the upper and lower rock walls. I had no steps, so I had to access it via a slope at one end. We have since built the steps and will be installing them soon. While steps remove some of the planting areas, access takes priority.

Food Forest and Banana Terrace Zones

Next up, I started work on the terrace below the Perennial Terrace and shed. It is relatively flat but slopes towards our water tanks with no retaining wall. My initial plan was to work on the soil. I sheet-mulched this area and planted pumpkins and sweet potatoes. At one end, I planted my three dwarf banana cultivars into giant grow bags, an experiment to see if they could produce fruit in ‘pots.’ So far, they have all thrived in 100L bags, but I’d use 200L next time. I planted potatoes into grow bags and let them sit in this area.

As it’s turned out, pumpkins are like naughty teenagers looking for any opportunity to escape! They scrambled UP the rock wall into my Perennial Terrace Garden and down around the water tanks. Despite their antics, I’ve let them have some additional space since we’ve harvested well over 100kg of pumpkins from this small, narrow bed. I will add more compost and thick mulch to build up the soil; eventually, we will retain it. Meanwhile, it will remain the spot for our ‘wild child’ crops to come and go seasonally.

Lower terrace gardens

Lower Terrace Gardens

Food Forest, Pickleball Court, and Raised Planters

On this same level, below the house, we had multiple issues. There was no retaining wall, just an irregular battered slope with weeds and rocks. It was challenging to whipper-snip and maintain. There was a flat pad below this slope, but it was a weedy nightmare and unattractive. The lower side had bush rock, and the area wasn’t wide enough to be functional. However, it had great potential.

The bluestone rocks here are like icebergs with a small cap showing on the surface but a titanic-sized ton of rock submerged. My husband took on the challenge and got heavy equipment to excavate. We created a wider flat pad and new retaining walls. He poured a concrete pickleball court with planters and garden beds by extending the pad just above our sloping orchard.

We used 1.2-ton concrete blocks to create the main retaining walls and smaller besser blocks for the low retaining walls and planter boxes. The concrete blocks do have an industrial look, but sandstone was hideously expensive and hard to build with as they are not even. We couldn’t dig holes for steel posts into the rock, so for the most part, sleeper retaining walls were not an option. We had to think creatively.

Raised walls for gardens

Raised Walls for Gardens

We’ve installed steps at either end so I can quickly and easily access my new Food Forest, the court, and the orchard. Drip irrigation systems are being installed next.

The result? We’ve redesigned an unsightly area, created a new terrace for my food forest and a pickleball court for exercise, and removed the need for weeding or high maintenance. The raised planter near the water tanks has steel posts and horizontal wires for my passionfruit to grow as a living screen for this utility area. The trellis will eventually wrap around to the Banana Terrace, and I’ll plant a colorful garden. We will paint the concrete blocks used for the retaining walls to soften the hardscapes and complement the court colors. The capping provides ample seating for watching the game or enjoying the view.

The rock walls are made from rocks originally excavated when the house was built. To soften these and deter snakes from using them as habitat, I have stuck cuttings of Dogbane (Plectranthus caninus) into the clay soil between them. This drought-hardy plant fills in the gaps, adding pops of seasonal color. It survives on rain and dew.

Lower Sloped Orchard Zone

The steepest part of the property is our fruit tree mini orchard and ornamental tree zone. It isn’t easy to walk around. However, we still need to maintain and harvest from our fruit trees. The clay soil can become incredibly hard and dry during summer and drought. After the rain, though, the weeds sprout up! Covering it with mulch around the fruit trees has been a priority to lock in moisture, prevent weeds, and protect the soil from erosion. Trees have also benefited from the organic matter and the microbial communities helping feed them.

Unfortunately, much of the ripe fruit rolls down the hill to our bottom fence! The mulch is slowing it down, and hay bales have been a temporary measure to put the brakes on and prevent erosion and nutrient loss.

Watering this zone is challenging as it’s too steep to safely access with big equipment. So, we plan to install a couple of IBC 1000L plastic tanks to take the rainwater overflow from our main tanks. We’ll use this to water and liquid fertilize our fruit trees. Hopefully, we’ll enjoy a bigger harvest in years to come.

AuTOMatic Mower

Finally, our block is on a corner at the top of a very steep hill. Our verges were one of my husband’s first challenges when working out how he would mow safely. His genius solution was a Husqvarna robotic mower! We affectionately named him ‘Tom’ as he not only solved our dilemma by navigating the steep slope but works day and night in any weather. This has been brilliant in summer when the grass seems to grow overnight. We plan to get another model for the lower-sloping orchard once we create barriers.

While sloping blocks have their challenges, they also offer incredible potential for landscaping to optimize garden spaces, attractive views, and spaces to enjoy. Besides, it keeps us fit, and hills are cheaper than gym fees!

Hillside gardening


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Anne Gibson

Speaker, author and urban garden community educator.

Anne Gibson, The Micro Gardener, is a speaker, author and urban garden community educator on the Sunshine Coast, in Queensland, Australia. Anne is passionate about inspiring people to improve health and wellbeing, by growing nutrient-dense food gardens in creative containers and small spaces. Anne regularly presents workshops, speaks at sustainable living events, coaches private clients and teaches community education classes about organic gardening and ways to live sustainably. She has authored several eBooks and gardening guides. Anne shares organic gardening tips and tutorials to save time, money and energy on her popular website.