Sustainability in Gardens

Ross Palmer

My personal take on sustainability

Like so many things in our hyper connected world, the word “sustainability” is bandied around and applied to almost any human activity whether warranted or not, think greenwashing…….. I would like to outline my thinking on sustainable gardening by firstly asking the question; What does it mean in my context?

I’ve been developing an analogy to help me with the concept, namely the concept of a personal budget, a leger if you want, regarding resources that I deploy in my garden. We all understand the concept of income, capital and external capital. We understand the concept implicitly that we can’t spend all our capital without financial ruin. External capital must be paid back with interest!

The way I think of this in these terms is this:

• Existing capital/Resources within the garden. Resources at my disposal that exist. For example, vegetation, nutrients, soil, my labour and time, water (tank, spring), mulch, rock etc

• External Capital/Resources. Resources I use from external sources, water, labour, compost, pumice, Building materials, fertiliser etc

• Existential capital/Resources. Climate, ecosystem, society etc

From the perspective of a sustainability budget, the first two of the above are obvious however the third item is often overlooked. Existential capital are all elements that we rely upon that don’t appear on balance sheets.

Think of water resources. Water from town supply, wells, damns are all effected by climate and the landscape we reside in. Cleared hills hold less water that forested which slow water filtration giving more water into the aquifer during dry period is one example. There’s no accident that water catchments surround our cities the forests are protected. Additionally, our water use needs to reflect the availability to others and the environment. It’s a shared resource therefore it’s use within the garden needs to be considered and not be wasteful.

Welton house

The lawns

An example of the ledger in action at Welton house Garden:

• Existing capital/Resources use is the creation of compost. The dead/cut plant material, non-seeding weeds: grass clippings, hedge pruning’s, dead herbaceous tops and the like. This is an existing resource that is put through a process, namely composting and redeployed where needed. A reallocation of resources, nutrients and organic material from one part of the garden to another.

• External Capital/Resources. The composting process has other inputs, labour (gathering and redistribution), machinery (Mini tractor for turning the pile), lime to sweeten the pile to optimize decomposition and animal manures to increase nutrients.

• Existential capital/Resources in the form of climate and ecosystem in the form of rain, water in dry periods and fungi/micro biota/worms to facilitate the entire processes above.

The above scenario is a sustainable part of the overall ledger to the garden however much depends on the decisions made to mitigate the issues that come from a reallocation of resources can create.

In the case of Welton, decisions are made in this regard. For Example:

The Tussock garden. Some herbaceous plants are much better performers in a lower fertility soil being less leafy requiring less staking, dividing, more resistant to Marlborough wind whilst still providing plenty of flowers for the summer. The removal of plant material from this bed sits as a nutrient/organic material loss annually gradually reducing the fertility of the bed over time. Soils/plants still need organic material to remain heathy therefore a high carbon low nutrient mulch (Arborist wood chippings from the property an existing capital) is applied as an annual mulch. This is highly sustainable.

Another large herbaceous bed, the Big Border, the plant material there performs much better in high fertility soils being plants of wet places and requires a duvet of compost returned every winter plus a weed suppressing high carbon mulch. Slightly less sustainable because of the higher inputs however no additional fertilizer is necessary and the bed performs well every year. The nutrient equation is roughly neutral with no additional fertiliser applied.

Lawns. Grasses dominate in high fertility soil therefore the removal of the clippings represents a loss of fertility with every cut, particularly nitrogen and with a corresponding reduction of vigour of the lawn grasses. A decision for a perfect lawn would require extensive inputs to rectify the losses in the form of artificial fertiliser, mostly Urea, therefore the decision was made to accept a “weedy” lawn. The lower fertility encourages more broadleaved forbs and therefore flowers, buttercups, Pratia, clover etc which we love! Additionally, the flow on effect of accepting the broad-leaved weeds has completely stopped the need for herbicide applications and the toxic waste of grass clipping that can’t be used in the compost recycling which used to be sent to the local landfill. In short WAY less inputs, time and materials and the hidden cost; the cost to the existential capital in the form of nitrate/herbicide pollution of the ground water, methane at the landfill and therefore the wider environment. Wasn’t a hard decision for us!

The hedges do need feeding occasionally and for this we use pelletised chicken/sheep manure. Clearly an external input so therefore a slight negative on the ledger.

Of course, there’s more to the compost story in the granular detail as this is just some of the major elements and the decision making that is involved when we’re looking at our processes in the garden through a sustainability lens. Worth noting is that compost is carbon neutral as at most the carbon within the plant material came from the atmosphere and will ultimately be returned in time.

Could this process be more sustainable? The answer is yes, an electric tractor and other vehicles used to transport the green waste and compost would reduce the carbon emissions (existential capital) of the process. Rome wasn’t built in a day!

This is just one example of how to think of sustainability within the processes of our gardens. A one size fit all concept is a bad one as different places/people require different solutions and for some people a “weedy” lawn is a sign of bad practice! For instance, I have no large compost system for garden waste here in my garden in Wellington because of the extreme terrain, (no wheelbarrows). I practice a “Chop and Drop” methodology, nothing leaves site.

There are many elements in a garden worthy of consideration which I haven’t covered; water use, pesticide/herbicide use, fertiliser use, planting design, etc etc etc. It’s a big list!