The implications of trying to squeeze more people into our cities and suburbs are far more than most people realise.

• More buildings means that fewer plants are filtering pollutants and producing oxygen.
• More hard surfaces (roofs, pavement, roads) reduce water absorption, increasing flood risks.
• Temperatures rise without plants to offset excessive heat resulting in the urban ‘heat island’ effect.
• Gardening culture is threatened if future generations grow up in compact gardens, risking the loss of traditional gardening knowledge and experience.

These challenges are only part of the problem, but a growing movement of concerned gardeners and enlightened horticulturists is actively developing solutions.

Expanding the Urban Tree Canopy

Trees are our main defence against urban environmental problems. They support biodiversity, cool the air, absorb rainwater to lower flood risk, buffer strong winds to reduce infrastructure damage and offer eco therapeutic benefits for psychological health.

However, success relies on informed tree selection and appropriate management. Uninformed decisions can lead to root damage to infrastructure, safety risks and ultimately unnecessary tree losses.

Three very important considerations when creating a tree canopy are:

1. Choosing the right species based on site limits and climate suitability.
2. Choosing the right plants for the understory; consider the impact of shade and roots.
3. Ensuring through soil preparation, trees need an unrestricted, good quality, soil mass for root expansion.  Even small trees can require at least 5 cubic metres. Plant trees into a hole that is around 3 times the diameter of the root ball.

Small Gardens

No space is too small for gardening.

• Even if you only have indoor areas, you can absolutely still grow houseplants.
• One of the best hydroponic gardens I’ve seen was on a four-square-metre high-rise veranda, packed with container plants and vertical systems run off automated irrigation.
• In courtyards fill small spaces with pots. If the ground is concrete, just set up raised garden beds or no-dig beds right on top of the pavement.
• Renting? Stick to containers so your entire garden can easily move with you.
• Grow your own food; many high-yield plants thrive in tight spaces - like tomatoes, cucumbers, capsicum, herbs, bush beans, chives, and spring onions.

Tips for Growing Container Plants

• Over or under-watering is a common issue. Always feel the soil 2-3 cm down before watering or use a moisture probe if you're uncertain.
• Use top-quality potting soil.
• Nutrients wash out easily, making regular feeding important, but over-feeding burns roots.
• Exposed containers dry quickly - wind, direct sunlight, and indoor air conditioning all accelerate drying. Also, porous pots like terracotta dry out faster.

Green Walls

Vertical gardens add plants by using wall space instead of ground space. Whether on a building, fence, or trellis, vertical foliage cools the area and softens the aesthetic.

They typically involve two methods:

1. Climbing plants: Grown from the ground up. Roots need good soil and the species must be manageable. Because plant mass becomes heavy, especially after rain, the structure must support the weight without damage.
2. Wall containers: Attached bags, pots, or hydroponic channels, usually run off automated watering. Ensure there is adequate support for the weight of the growing media when fully wet.

Caution: Match plants to the structure. Invasive species like ivy can cause structural damage unless constantly monitored and maintained.

Green Roofs

With expertise, roofs can be turned into thriving gardens. New buildings can be engineered and built to support the weight of a roof garden after rain, and to protect the building underneath. Existing buildings however may require more careful consideration, and the expertise of specialists to determine the right way to prepare for and  manage a garden on a rooftop.

Community Gardening

People who have limited space available at home are increasingly finding other places to garden. 

• Volunteering is booming, from friends groups at botanic gardens to land care groups.
• School gardening projects (e.g. Stephanie Alexander Garden Foundation).
• Community Gardens and Allotment Gardens - thousands now exist around Australia
• Guerrilla Gardening  - people planting in public places e.g. road verges, waste land.

Public Landscaping Initiatives

Government authorities are increasingly embracing projects to increase greening of urban areas:

Eg.  Melbourne City council has implemented a swathe of urban greening initiatives that includes Green on Rooftops initiative (demonstration green roof at 1 Treasury Place).

LEARN MORE:  Study Biophilic Landscaping