Definition
Backyard gardens are privately managed residential green spaces that, when intentionally designed and maintained, can provide habitat, food resources, and ecological connectivity within urban environments.
What this strategy does
This strategy leverages cumulative, small-scale planting, habitat features, and low-intensity management across private properties to support urban biodiversity.
Context
In many Aotearoa New Zealand cities, private residential land makes up a substantial proportion of total urban green space. Collectively, backyard garden design and management therefore play a significant role in shaping urban biodiversity outcomes, particularly in suburban neighbourhoods.
Technical considerations
Design considerations
Spatial configuration and connectivity
Design gardens as part of a wider network of vegetation, functioning as stepping stones between parks, reserves, riparian margins, and other green spaces to support wildlife movement.
Vegetation structure
Use diverse, structurally layered planting (trees, shrubs, groundcovers, climbers) to increase habitat availability and support birds, invertebrates, and lizards.
Plant selection
Prioritise locally appropriate native species where possible, while recognising that some non-invasive exotic species can contribute to structural diversity and food resources.
Habitat features
Incorporate logs, dense ground cover, and refugia to support lizards and invertebrates. Install bat boxes only where bats are known to occur locally. Consult an ecologist about the appropriateness of installing bird nesting boxes.
Implementation considerations
Garden management intensity
Reduce mowing frequency, retain taller and structurally diverse vegetation, allow leaf litter to accumulate where appropriate, and minimise pesticide use to support soil organisms and invertebrate food webs.
Soil health
Use mulching and organic amendments to improve soil structure, moisture retention, and biological activity.
Bird feeding
Prefer plant-based food sources. Artificial feeding should be used cautiously, as it can alter bird community composition.
Issues and barriers
Space constraints
Small lot sizes can limit habitat extent, although layered planting and building-integrated vegetation can help offset this.
Invasive species risk
Poor plant selection and unmanaged gardens can introduce invasive plants or pests that negatively affect native biodiversity.
Domestic cats
Free-roaming cats exert significant predation pressure on birds, lizards, and invertebrates. Cat confinement or cat-free development approaches can substantially reduce wildlife mortality.
Social and behavioural barriers
Aesthetic norms, maintenance preferences, and upfront costs can limit uptake of biodiversity-supportive garden practices.
Synergies and opportunities
- Human wellbeing – Supports mental health, social connection, and everyday contact with nature across age groups.
- Food security – Pollinator-friendly and edible plantings contribute to household and community food resilience.
- Climate change – Vegetated gardens contribute to urban cooling, stormwater regulation, and climate adaptation when managed collectively.
Financial case
Ecosystem services and performance value
Distributed ecosystem services
Residential gardens collectively provide pollination, pest regulation, and soil-supporting functions that reduce reliance on external inputs.
Cost-effectiveness
Low-cost, cumulative impact
Household-scale interventions enable biodiversity gains at relatively low cost compared with large, centralised restoration projects.
Monitoring and evaluation metrics
Core metric
Presence and activity of birds, pollinators, and invertebrates can be measured through observations and simple repeat surveys.
Advanced metric
Residential biodiversity performance can be assessed using Gardenstar and the New Zealand Biodiversity Factor – Residential (NZBF-R).
Case study
Gardenstar tool
Related design strategies
- Artificial micro-habitats
- Compact high-yield urban agriculture techniques
- Container gardens
- Maintenance for biodiversity
- Natural micro-habitats
- Pollinator pathways and flora plantings
Additional resources or tools
iNaturalist NZ
https://inaturalist.nz/
Department of Conservation – Gardening with native plants
https://www.doc.govt.nz/get-involved/conservation-activities/planning-and-planting-a-native-garden/
People + Cities + Nature – Garden Star Tool
https://www.peoplecitiesnature.co.nz/garden-star-tool