Footpath Gardening: To Boldly Garden Where No One Has Gardened Before…

Bellis nature strip, Brisbane: producing pollen, nectar, food and medicine

Bellis nature strip, Brisbane: producing pollen, nectar, food and medicine

Would you like to put some nature in that ‘nature strip’? Gardening in public open space is known to reduce petty crime and improve neighbourliness, and that’s what I hoped to encourage when I swapped managing Sydney Botanic Gardens for establishing a model, affordable sustainable house and garden in subtropical Queensland, in 2003.


As part of the Development Application to retrofit ‘Bellis’, my home, I negotiated with Brisbane City Council and got approval to upgrade my turf footpath strip into a productive plot.

At the time I didn’t realise this simple act of gardening would be frustrated by vandalism or that footpath gardening would occasionally become a political hot potato in Brisbane.

Economic, social and environmental benefits of gardening

A turfed footpath strip is one example of a living surface to cover the ground between property fence lines and the street. Well maintained, these strips of cultivation brighten and soften a streetscape.

Several studies have shown that sought-after properties tend to be in streets lined with shade trees and gardens, and that homes with well-tended gardens sell for around 10% more.

I’ve managed public parks, gardens, urban forests and green space in public housing estates in London and Sydney. Through work I’ve learned that one way to defeat graffiti, the destruction of new trees or plantings is rapidly repairing damage, ideally within 24 hours.

Vandalism should be expected. The best way to deal with this is growing ‘sacrificial’ plants: don’t become too attached. Have some back up stock ready.

When Brisbane City Council offered to supply and fit protective tree cages around the three new street trees I planted in my footpath garden, I couldn’t refuse.

Footpath gardening provides ‘social services’: gardeners who are outside and visibly tending public open space assists people to get to know neighbours. Picking up litter tends to reduce further littering. Footpath gardening is no small advantage in big cities where we often find we don’t know many neighbours.

Footpath gardens and street trees also provide environmental services. In 2003, the CSIRO predicted the Urban Heat Island effect, where hardscapes and buildings soak up heat and dry out land, would double between 2000 and 2050. For many years, Brisbane City Council has been using thermal satellite imagery to locate city hot spots in need of additional street trees.

The living surface provided by footpath gardens and shade provided by trees help cool streets. By moderating the local microclimate, nature strips and trees help reduce household air conditioning bills.

Nature strips also mitigate stormwater flows. Their rough surfaces slow the movement of storm water which helps collect silt and nutrients from soluble garden fertilisers. Potential pollutants are mopped up, rather than being flushed into rivers and oceans.

At the end of my street is a creek which drains into Moreton Bay, a RAMSAR-listed wetland of international significance. Moreton Bay’s seagrass meadows famously support the only colony of dugongs living within cooee of a major city on Earth. Being sustainable includes reducing, not just stabilising existing environmental stresses those dugongs face.

In 2003, Brisbane City Council acknowledged nature strips and trees:

1. help improve stormwater quality and reduce peak flows, and
2. help reduce peak energy demand;

In assessing my development application, BCC asked me to address these council environmental criteria. Their third criterion was to reduce potable water consumption. I agreed to all three. We had a plan.

Getting started

Most soils need decompaction, the addition of organic matter (compost, well-rotted manure). There may also be builders’ rubble and other buried waste from street maintenance.

Liming is likely to be required, since the majority of soils are acidic. Many gardeners are aware that testing soil for pH informs them if, and by how much, the soil must be conditioned so test results fall between slightly acidic (pH 6.5) to neutral (pH 7).

The easiest location to start footpath gardening is the strip of soil between the fence line and the footpath. This is the zone which is the natural habitat of the picket fence. Beautifying this band of soil can seamlessly marry the property into the streetscape. It’s the first and least controversial step towards making a streetscape more park-like. Since plantings are unlikely to be trodden on, there’s a good range of suitable plants (see gallery).

There are numerous examples of this zone being planted around Brisbane. Geraniums, agapanthus, hippeastrum, day lilies, iris, lilyturf, lomandra, ixora, gardenia, gerbera, gazania, petunia, cycads, native grasses and lavender are commonplace and highly successful. Walled gardens sometimes have flowering climbers, like star jasmine, trained against lattice or shrubs, like yesterday, today and tomorrow (Brunfelsia) clipped into neat screening panels of vegetation.

In my footpath garden grow bird and bee-attracting flowers, trees, herbs and medicinal plants. I planted Aloe vera and dwarf rosemary ‘Bennenden Blue’. Peta, a neighbour two doors down, gave me a small pot of Aloe vera in 2004 which I gradually multiplied over three years. In order to give this succulent adequate drainage during wet summer weather, I created a ridge of soil, 15cm high, and planted cuttings in the top.

Nature strip safety is vital. Plants in nature strips should not be spiny or allowed to overgrow and cause trip hazards, to impede strollers, wheelchairs, or block lines of sight. The effect should not be overgrown or claustrophobic, but park-like.

My Aloe vera is a soft-spined cultivar (some are prickly). If a skateboarder falls flat on their face on the Aloe vera border, the worst thing that will happen is they become heavily moisturised.

Now well established, I give away divisions of Aloe vera at Open Days and many passersby ask for pieces. Some help themselves. It’s surprising how such a ubiquitous plant sustains interest, but that’s because streetscapes are often dull and monotonous.

The more complex zone is the strip of land between the footpath and the kerb. This is where people get into and out of vehicles, where drivers need to see pedestrians. Here, plantings need to be more cautious and there are fewer resilient plant species.

The need for resilience to regular trampling in this zone is why lawn grass has become the default living surface. Queensland blue couch, common couch, buffalo, sweet smother grass (also known as Durban grass) and kikuyu are the most durable. Variegated buffalo grass is rarely seen, but makes handsome turf (see gallery).

In this zone, Brisbane City Council uses kerbside gardens to direct pedestrians. Edith Street, Wynnum, is an example where plantings are used to restrict pedestrians from crossing the road, directing them to spots designated for crossing. In areas where crossing is not easy, safe, or pointless (such as ramp entrances and exits to tunnels) council has installed extensive kerbside plantings.

Selective herbicides are very popular for suppressing turf weeds, however, they were developed for use in the cool seasons (at or below 21C) and on fine-leaved cool-season grasses, like Fescue, Bent grass and Rye grass, most of which are not grown because they can’t cope with warm climates. Of the five warm-season turf grasses mentioned, only common couch (Cynodon dactylon) isn’t harmed by these chemical herbicides. So-called ‘weed and feed’ lawn chemicals teach bad horticultural practise. They may be widely available, but home gardeners cannot apply them accurately or according to the law, without proper training and equipment.

The horticultural challenges of gardening in this zone are significant: trampling by pedestrians, shade from evergreen trees, competition for water by tree roots, greater exposure to vandalism, sunshine and reflected heat from paths and roads, and greater desiccation by drying winds. Watering is not really desirable, apart from establishing new plantings in the first few weeks, because water wastage is hard to avoid and plants must survive watering restrictions during drought. To help solve this, Brisbane needs some footpath gardens with varied challenges to trial alternative living surfaces.

When I moved to Wynnum, locals said my suburb is supposed to experience frost once in twenty years. During the drought of 2004 – 2010, the kerbside section of my nature strip experienced five frosts of -0.5C. It’s only just a frost, each vanished at sunrise, but when you’ve planted frost-sensitive plants the damage, though temporary, can be dramatic. Especially if it occurs a week before an Open Day!

My top plant for this zone is sweetpotato: a vandal-proof, drought-tolerant, easy care, productive, decorative groundcover that tolerates foot traffic. I first noticed it being used in public open space in Java and Cairns. I started by growing golden-leaved ‘Marguerite‘ in formal bedding displays at Sydney Botanic Gardens. It produces a decent crop of tubers and the shoot tips and young leaves can be cooked and eaten like spinach. Currently, I’m growing purple-leaved ‘Ace of Spades‘ because my guinea pigs prefer eating its leaves to other kinds of sweetpotato. Both flower well and attract bees.

My garden has grown up to become habitat for a rare species cranefly, Nephrotoma australasiae, the 399th animal species recorded living in (or visiting) Bellis. Its discovery here makes my garden the sixth recorded location for this species in Australia. Amongst other plants, it lives in my sweetpotato. My footpath garden is a conservation site and Wynnum is now officially on the Atlas of Living Australia. I recommended both ‘Marguerite‘ and ‘Ace of Spades‘ sweetpotato to Brisbane City Council to plant in their Epicurious Garden at South Bank.

Deficiencies and toxins

Intensive food production was one of my ambitions at Bellis. Food safety is crucial whether it’s grown in a garden or on public land. Mineral and nutrient deficiencies must be managed, otherwise crops will be nutrient-deficient. The importance of healthy food and the risk associated with growing them in contaminated soil increases the more you rely on home grown.

It is a duty of care to have soil destined to grow food analysed for toxins and deficiencies before any is consumed.

As well as silt and nutrients, floodwater may transport pollutants. The Brisbane floods of 2011 were an important reminder of this.

I grow food on my nature strip because I knew what I was dealing with before I started eating anything home grown.

Lead and copper can remain in kerbside soils for many years and certain crops, such as silverbeet, turnip, beetroot and radish, bioaccumulate heavy metals, soaking up and concentrating what is present in the soil. The presence of toxins limits the range of food plants that can be consumed.

The National Measurement Institute recommend growing a test crop of silverbeet. I had baseline tests for deficiencies completed before I improved my soil. They analysed 2kg of silverbeet. Gardening Australia filmed me reading out the test results – a moment of truth. Once I had the all clear, I started growing food.

The sweetpotato I grow in my nature strip primarily feeds pets (my lawn is their pasture, and it gets heavily trampled during annual Open Days). The Aloe vera sap is used to remedy sunburn and the rosemary is for the kitchen.

Testing was repeated after five years of cultivation and soil improvement because I wanted to verify progress and identify issues, such as managing ongoing iron deficiency.

In my footpath garden grow Wallum Banksia, Banksia aemula. This is a living experiment designed to see if the phosphorous I have added to my phosphorous-deficient soil is leaching out of my vegetable garden in the back garden and being carried by sub-surface water into my footpath garden. Banksias are highly sensitive to phosphorous. If I feed crops in my footpath garden I apply a slow-release fertiliser for native plants to the soil. I foliar feed crops with seaweed. The solution is mostly absorbed by the leaves. Eleven years after planting, and after three summers of flooding rain (2011, 2012, 2013), my Banksias are still growing and flowering.

Services

Many nature strips look threadbare because they need decompaction and aeration. It is critical that underground services are located before digging commences.

Service location devices are useful for differentiating between gas, water or electricity cables. I always carried a locator for tree work in London. I was shocked to find Sydney Botanic Gardens didn’t have one when I joined in 1992: locaters are important because service plans and maps can be inaccurate or out of date.

The combination of overhead cabling and underground services often prevents continuous planting. In this instance, low-growing trees, like bottlebrush (Callistemon spp.) may be planted in tree pits and the pits can be planted with annuals and perennials.

My footpath garden contains a plastic stormwater pipe. I had the gas main extended along my footpath so it could supply my home. My footpath garden doesn’t contain power or optic cables. The last thing a gardener wants to do is to damage services, so be informed, not surprised.

Which plants succeed?

Ground covers are a good fit for footpath planting, if the right plant is used in the right conditions. A ground cover is a plant that grows over an area of soil. They may be used to provide protection from erosion and drought, to moderate the urban heat island effect, grown to inhibit weed growth, or grown to improve the aesthetic appearance of bare earth by concealment.

In the wild, the ground cover layer is formed by low vegetation growing below the shrub and tree layers. The most widespread ground covers used in the built environment are grasses of various types, including lawn grasses.

Certain plants are grown as ground covers on industrial spoil heaps not just to prevent erosion or dust pollution, but also to bioremediate the ground. This is where plants or other organisms are employed to remove or neutralise pollutants from a contaminated site. Melastoma malabathricum, a native shrub which bioaccumulates aluminium, is one of the most commonly grown bioremedial plants in Australian gardens, although it is grown as an ornamental.

Certain species also act as unwanted vectors of disease. Carpet grass, Axonopus compressus, is a vector of root rot fungus Rhizoctonia solani, an incurable and cosmopolitan disease which harms over 500 of the most widely grown ornamental and edible plants. Carpet grass is sold as seed and is a traditional lawn and nature strip grass in frost-free zones in coastal eastern Australia, Queensland especially. Get over it.

Rhizoctonia root rot is a common cause of plant failure during wet summer weather where soil is poorly drained. This plant-disease association is a common risk in community gardens using grassed surfaces as footpaths. Get rid of it.

Lawn grasses are generally laid as turf. But ground covers are usually grown in cells or tubes for planting individually. Cells may be planted through holes cut into a weed mat, a landscaping fabric designed to allow air and water to percolate through. Weed mats are often biodegradable tarpaulins, commonly sold as ‘mulch mats’.

In gardening jargon, however, the term ‘groundcover’ refers to a wide range of plants that are used in place of weeds. Some which have been used historically, such as Singapore Daisy, have proven to be invasive and as bad as weeds. This weed was spread around Queensland by Queensland Rail. The irony of this weed is that QR used it to reduce soil erosion along embankments, but research has proven it accelerates erosion.

Ground cover types:

Vines, which are woody plants with slender, spreading stems, often pegged down. Not ideal for nature strips but possible to employ Wonga Wonga vine, Pandorea pandorana between the fenceline and the footpath;

Herbaceous perennials, including low-growing ornamental bulbs, like storm lily (Zephyranthes spp.), Hemerocallis littorals, Kaempferia, comfrey, Iris, Daylily, Hippeastrum, Geranium, Gazania and Bacopa.

Dwarf lilyturf (Liriope muscari), Dwarf Mondo grass (Ophiopogon planiscapus), Moses-in-a-cradle (Tradescantia spathacea) and Society Garlic (Tulbaghia violacea), are signature kerbside plantings of Brisbane City Council. I’ll wager few people know Moses-in-a-cradle has medicinal uses. Wear gloves when handing it and avoid getting too much sap on your hands, in your eyes or mouth. Fresh juice may cause a rash to people and pets, dogs especially;

Shrubs of low-growing, spreading species, including Dwarf Rosemary ‘Bennenden Blue‘, Dwarf Powderpuff, Calliandra haematocephala ‘Prostrata’. The latter is another plant which Brisbane City Council has successfully trialled;

Cycads, including Cardboard fern, Zamia integrifolia, a signature kerbside and median strip species used by Brisbane City Council;

Dwarf and ornamental grasses, especially low-growing varieties, like Themeda ‘Mingo’, Temple grass, Zoysia spp., compact cultivars of Lomandra, Pennisetum villosum and P. alopecuroides;

Turf grasses, like Qld Blue Couch, Common Couch, Buffalo grass, Temple grass, Kikuyu grass;

Succulents: Burn Jelly plant, Bulbine frutescens and Aloe vera (soft-spined cultivars only) are suitable for low or no traffic areas;

Other common groundcovers include:

Ornamental cultivars of Clover (Trifolium);
Dichondra ‘Silver Falls’, grown at Brisbane’s Roma Street Parkland. Beautiful;
Gazania;
Junipers of various low-growing types, especially Juniperus conferta. I used this in a consultation for a ‘no mow’ turf alternative at St Mary’s Cathedral, Sydney;
Mint, Mentha species, especially Mentha spicata, in moist soil;

Living mulch. Ground covers may also be used to grow mulch. Comfrey is popular in permaculture but this is too thirsty in the subtropics. In my experience, sweetpotato is superior in the subtropics, being aesthetically pleasing, waterwise, edible and with a longer growing season.

Tapestry lawns. This is where a mixture of ground-hugging plants are mixed into a predominantly grassed groundcover (see gallery). They are planted in a checkerboard fashion and then allowed to naturalise. Native tapestry lawns can be planted using Australian Harebell (Wahlenbergia spp.) and Isotoma maxillaries (both grow wild in my street); Native lemongrass (Cymbopogon ambiguus), Weeping Meadow grass (Microlaena stipoides) and the ornamental form of Kangaroo grass (Themeda triandra ‘Mingo’).

Ornamental pattens (such as the herb butterfly, see gallery) may be used where resources and conditions permit.

Top Tips

If you wish to boldly garden where no one has gardened before, remember that soil in your nature strip is unlikely to be pristine. A successful footpath garden is where both the crop plant and the soil are actively and consistently cultivated.

Low maintenance doesn’t mean no maintenance, especially during the establishment phase. I water new stock six times: at planting and once more during the first week, then once a week for the next two weeks, them twice a fortnight apart. Upkeep involves keeping paths and gutters clear of soil, mulch, weeds and avoiding overgrown vegetation.

  • You’ll need to negotiate with your council, and to confirm the presence or absence of underground services before you dig.
  • Take time to select the right plant for the right position and growing conditions.
  • Test then improve your soil. Contaminated soil may never be suitable for certain crops.
  • Mowing strips help contain rhizomatous plants and mulch and mulch mats aid establishment.
  • Grow waterwise, hardy, reliable, durable plants.
  • Start by planting the zone between the fenceline and the footpath. It’s easier and there’s a wider range of suitable plants you can find in a nursery.
  • Planting around street tree bases is an easy option for getting started.
  • Tackle the more challenging zone between the kerb and the footpath last.

The choice of plants is fairly broad. Locating sources of affordable stock can be harder. Some will not be sold retail, but through community gardens; some may not be sold in bulk, or as juvenile stock at affordable prices. My current footpath garden took time and space in the back garden – I prepared by multiplying enough purple-leaved sweetpotato ‘Ace of Spades’ plants to fill my footpath garden in a single plant out.

Please be prepared for vandalism. I defeated them in London. Australia doesn’t experience the same level of damage as London, and vandals don’t have to win.

If you become a footpath gardener you will have become a volunteer community gardener – surprisingly close to the kind of public spirited volunteer who assists Southbank, Roma Street Parkland and Mt Coot-tha Botanical Garden. Lets’ hope it’s not too long before Brisbane City Council offers classes in footpath gardening and acknowledges our contribution to a brighter, more park-like city.

Welcome to the world of public gardening!

Jerry Coleby-Williams
first draft 14th October 2015, Brisbane
second draft, 15th October 2015, Bangkok
published, Ho Chi Minh City, Viet Nam