A Sustainable Backyard – Hamilton Gardens, NZ: A Productive Urban Garden Demonstration of Permaculture Principles
Hamilton Gardens is one of New Zealand’s notable and most recently established public gardens. Development began in the early 1960s but most of the development has occurred since the early 1980s on a former landfill rubbish tip next to the Waikato River. The 58 hectare garden is now one of Hamilton’s treasured green spaces.
As well as traditional formal rose and camellia collections, nurseries and glasshouses Hamilton Gardens’ most significant features are its magnificent themed gardens – one of which is The Sustainable Backyard.
A Sustainable Family Garden
The Sustainable Backyard is based on the traditional New Zealand quarter-acre section (1000 square metre lot) with the aim of providing a family of two adults and two children with much, though not all, of their requirements for vegetables, fruit and eggs.
The garden was designed and is managed on permaculture principles of ‘cultivated ecology’. Permaculture aims to ‘work with nature’ by creating a self-sustaining, low maintenance productive ecosystem in which the ‘waste’ products of one part of the ecosystem are recycled as a resource for others. Plants and animals are chosen not only for their food value, but also for their role in providing a favourable habitat for other beneficial companion species. Several techniques of permaculture, organic and biodynamic gardening are demonstrated in the sustainable backyard:
1) Companion Planting
Companion planting is a gardening technique which carefully chooses and grows compatible plants with one another to gain some practical benefit for one or both plants such as higher yield or improved pest control. Companion planting can also combine productive with aesthetic benefits where companion plants are chosen because they also look good together.
Layering or stacking recognises that plants grow to different heights and have different rooting depths which reflect their unique requirements for space, light, moisture and nutrients. The overall productivity of an area of land can be increased by growing mixed crops with different growth habits so that they do not compete directly for resources. Examples include growing tall vegetables (e.g. leeks) amongst shorter bushy types (e.g. lettuces), vines (e.g. beans) growing on tall sturdy species (e.g. sweet corn), or growing compatible crops beneath fruit trees..
A compact dual pond system demonstrates the purifying and productive potential of aquaculture. The pond system can provide food from edible water plants (e.g. water chestnuts) and also a habitat for plants and insects beneficial to the rest of the garden.
4) Biodynamic Flow Forms
The sculptured flow-forms, based on Rudolph Steiner’s biodynamic principles, generate figure-of-eight flow patterns which aerate and purify the water which is circulated between the ponds by a solar powered pump.
5) Chicken Tractors
Chicken tractors demonstrate important relationships between plants and animals within a productive garden ecosystem. Portable coops are rotated around the garden beds in which chickens can scratch, cultivate and fertilise the soil with their manure. They also eat weeds, seeds and invertebrate pests, as well as producing eggs. After their labour saving bed preparation, the coop is moved onto another area leaving fertile, tilled soil ready for replanting.
6) Composting and Mulching
A family consumes only a small proportion of the total biomass produced by a sustainable backyard. Only parts of most food plants are used, e.g. roots, tubers, leaves, fruits or seeds. The unused plant and animal ‘waste’ can be recycled efficiently through compost heaps and a worm farm to provide a soil conditioner and plant nutrients for subsequent crops.
Mulching (with compost or other materials) protects and conditions the soil, retains soil moisture, helps control weed growth and prevents erosion. The mulch also provides a favourable habitat for beneficial invertebrates (e.g. earthworms and beetles) which incorporate organic matter and other nutrients into the soil where plants can use them.
Other permaculture components include a beehive (for pollination and honey), cultivation of the nitrogen fixing aquatic Azolla (for fertiliser) and the benefits of liquid herbal manures (for mineral micronutrients).
A Working Productive Garden
Hamilton Gardens’ Sustainable Backyard is not just a demonstration garden but also a working productive garden with an educational focus managed and maintained by volunteers from the Hamilton Permaculture Trust.