Design notes…

The wrap-around garden

Home and community gardening are a subset of the much-broader permaculture design system and, just as in wider society, catchy ideas come and go in permaculture. The circular, keyhole garden is one of these. It it the best shape for our vegetable garden? Like much else, the answer is: it depends.

The wrap-around keyhole garden at Randwick Sustainability Hub. Concept b y sustainability educator, Fiona Campbell. Design by landscape architect/permaculture educator Steve Batley. The raised gardens behind are self-watering (‘wicking’) garden beds.

IF YOU HAVE BEEN applying permaculture for a while you will surely have encountered a circular garden like that in the photos. It is usually called a ‘keyhole’ garden because the shape is reminiscent of that.

From what I recall the design came out of the early nineties, or was it the late eighties? It doesn’t really matter because the design became popular and was taught in permaculture introductory and design courses including the courses my partner and I taught in Sydney.

Permaculture course participants in a PacificEdge Permaculture Design Course construct a keyhole garden at the old Randwick Community Centre. Newspaper was laid as a barrier to weed growth after the area was cleared. The brick edges were fitted to minimise space between bricks to reduce opportunity for weed invasion, however it is difficult to avoid small spaces between bricks in a circular garden. Compost is being added. The path and squat space could accommodate two gardeners. Nowadays we might not garden shoeless like the woman in the photo.

Is the wrap-around garden more productive?

The principle, as permaculture educators used to put it (and might still do so), was to take the common rectangular garden and wrap it around yourself, leaving a narrow path to get in and out and sometimes a circular space at the end of a narrow access path in which to crouch to work in the garden. The keyhole is a nice analogy.

The theory offered to support the design was that the circular form conserved space and was easier to work and harvest. It as claimed to make the crops easily accessible, however that was contingent on other design factors. Is all of this true? To determine that we would have to delve into maths:

  • to compare the surface/growing areas of rectangular versus keyhole garden beds
  • to measure and compare the productivity of the two shapes.

There are other variables worth considering in this calculation:

  • the maintenance needs of any garden
  • path dimensions.

Are there other factors that increase or constrain productivity attributable to garden geometry?

How useable are keyhole gardens?

To compare the usability of the gardens we can call on ergonomics to assess whether the long rectangle or the circle with a path and squat space in the middle is easier to make, manage and harvest. Theory suggests the circle requires less human effort to move about, but there is a qualifier to that.

I’ve seen quite a few keyhole or circle gardens. Some have been productive and flourishing examples of the type while others have not. That, though, is a management and not a geometry issue. I could say the same for the classical rectangular garden bed.

One of the variables influencing the volume of vegetables produced is the access path into the keyhole garden. On many gardens I have seen, it has been too wide and consumed valuable garden surface area that could better be used for growing. In other words, the ratio of garden path to space has been too high.

For a home garden managed by only one or two people, 600mm is wide enough for the access path into the garden. Something around 650mm is sufficient diameter for the squat space at the end of the path where the gardener crouches to do their work.

What I have also noticed is how some keyhole gardens could provide greater growing area were they made wider than they sometimes are. It’s the path-to-growing-area ratio again, though this time it includes the path around the garden’s outer circumference.

Think of it this way. If we crouch in the space in the centre of the garden and extend our arm as if reaching for a juicy tomato growing at arm’s reach, we have a useful garden dimension — the reach of the gardener. This becomes a baseline measurement when we are designing our keyhole garden.

Now, in planning our garden, if we double that reach-distance then we can crouch at the outer circumference of the garden and reach into the garden to the same arm-length distance we reached from the inside crouch space. In other words, we can reach half way across the garden from the crouch space and half way from the outer circumference. A keyhole garden this double-arms-reach in width increases out garden to path ratio.

So, we can make a potentially productive keyhole garden in which access paths take little space and the growing area is larger. But there is another question about keyhole gardens. Two questions, actually.

In the Blue Mountains of NSW, a more complex wrap-around garden design of a type sometimes given the name of ‘mandala garden’. A central garden in which bricks have been spiraled to form a mound is planted to herbs. A circular path was built around the mound and narrow paths taken close to the edges of the rectangular area for access to the surrounding gardening space. Access to the whole garden is a prime design criteria for any garden and eases management. The entirety of the garden is reachable from inside and along its outside edges. The width of the paths is suited to the home garden.

Are circular gardens the optimal shape, or not?

The first question is about fitting the circular shape into the garden landscape. Were we to make a number of these circular gardens on a rectangular area of land, a suburban backyard, for instance, as I have seen done, then the space between them is significant because the circular shape doesn’t maximise utilisation of the whole garden area. It can be difficult to close-fitting circular garden beds in rectangular spaces and even when close-fitted there is still wasted space. Rectangular garden beds can be better close-spaced without loss of garden space between them.

One solution when designing the whole garden space is to divide it into squares with the keyhole garden at the centre of the squares, a narrow access path around the garden’s outer circumference, and the space beyond that out to the edges of the square area planted to other crops such as perennials, flowing species to attract pollinators and beneficial insects or soil-improving legumes for slash and mulch of the growing beds. The design utilises the long-established permaculture ideas of increasing plant diversity and planting in supportive guilds of crop/flowers/legumes. We just need to be careful that what we plant between the keyhole beds isn’t so tall it blocks light coming into the vegetable beds.

The keyhole garden can be our annual garden bed in which seasonal crops are planted and harvested and the surrounding growing space of our square planted to perennials.

The other question is about garden edges and how we maintain them. I’ve seen enough garden beds with poorly constructed edges, including in community gardens, to know that those edges become vectors for weed invasion. They must be well constructed and maintained to prevent this. Nothing is more boring than pulling weeds.

One idea is keeping paths well mulched with woodchips, although you will still get a few weds coming up. Some gardeners grow lawn paths. They are hardy but require mowing. Mowing a circular path around the circumference of a keyhole (and the undulating garden edges that some permaculture people like making) can be difficult. Best to make it the mowing-width of the lawn mover. Maintenance is a design criteria for keyhole gardens and undulating-edge gardens.

Is the rectangle the traditional garden shape because it is more manageable?

Garden visitors might find keyhole and other versions of circular gardens visually interesting, however as gardeners with limited time to spend in the garden we have to ask if the circle is the optimal shape.

In doing this, let’s think about the classic rectangular garden or square shape. The rectangular is:

  • simpler to build than the circle because wood planks or bricks used for edging or as a raised garden wall are rectangular in shape
  • easier to defend against weed infiltration; well-made rectangular garden edges have less potential for leaving gaps
  • where grass paths are used they are easier to mow; the path between rectangular garden beds can be made one or two mower-widths wide to simplify maintenance
  • wider-than-arm-reach rectangular garden beds are easily divided into rectangular sections by narrow internal paths or stepping stones.

The Randwick training garden

The keyhole garden in the photos is at Randwick Community Centre’s sustainability hub in Sydney. A training garden for the seven-meeting course in organic gardening that then-council sustainability educator, Fiona Campbell, ran there, the garden is scaled for use by groups.

The figure gives an idea of the scale and path dimensions of the Randwick training garden and demonstrates how the centre of the growing area can be reached from inside and outside the circle—two average adult arm-reaches in width. The path to the crouch space is scaled to accommodate a number of garden trainees as is the path around the garden circumference which is edged with a weed barrier sunken into the ground. The dimensions are those suited to an educational garden that accommodates a number of people and is too large for the home garden. After this photo was made the sandstone blocks forming the garden bed were cemented in place. This closed gaps between them to exclude weed growth and prevented the blocks being removed or, as the landscape manager at the local government where I was community garden and landcare coordinator explained, top prevent them being used as projectiles.

The garden has to accommodate a number of people at once. To do this, the access path and its crouch space at the centre are wider than a home gardener would make. This is a design criteria for shared garden beds in community gardens, too. The garden was designed to be two adult-arms-reach in width. The scale of garden and access path is a design response to the garden’s use as an educational installation. For durability and weed-deterrence, the edges have been cemented in place and no gaps left between stones where weeds could infiltrate.

A solid garden edge helps to exclude weed invasion. Sandstone blocks were cemented together to form a barrier against weeds and for public safety, as the garden is in a public place.

After each class the garden and whatever vegetables the class has planted in it is abandoned and left unmaintained, although course participants are welcome to return to collect the harvest. The next class then has the job, and the learning, of clearing, rebuilding, remulching and replanting the garden.

Keyhole? Circular? Rectangular? Which?

So, what is best? Circular or rectangular?

It’s less a question of best and more one of personal preference, landscape design, gardening skill and time for management and maintenance.

Measuring the productivity and ergonomics of the circular keyhole and the traditional rectangular garden would be a fine experiment for the gardener with a scientific brain.



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