Mass and Mixed Planting in Landscape Specification Across Australia

Mass planting has emerged as an essential strategy for landscape architecture in Australia over the last few decades, especially in the design of public spaces. They not only provide ecological and aesthetic benefits but also address practical concerns such as soil quality, climate resilience, and maintenance efficiency.

As specifiers become more ecologically-focused, they are turning their attention to mixed plantings, which share the same benefits as mass plantings with more diverse biodiversity resources and in-built resilience and redundancy.

If one species is impacted by pest or disease, the other species provide a buffer as they are less likely to be affected and may also help to slow the spread of pests and diseases.

For landscape specifiers, understanding how to harness these planting methods effectively helps create sustainable, functional, and engaging environments. Below, we explore the benefits of both mass and mixed planting while also examining the traits that make plants well-suited to these schemes.

Biodiversity and Ecological Value

Mass and mixed planting promote biodiversity, one of the most pressing concerns in urban and regional landscapes. By incorporating a diverse array of plant species, particularly Australian natives, these approaches create habitats that sustain birds, pollinators, and other wildlife.

For instance, layered mixed plantings in urban parks can serve as green corridors for pollinators like bees and butterflies, improving ecological connectivity.

The biodiversity benefits aren’t limited to wildlife; plant diversity itself contributes to functional stability. Mixed planting schemes introduce ecological redundancy, meaning that if one species struggles (due to pests or extreme weather), others can continue to thrive, ensuring the landscape’s overall functionality.

Mixed plantings can also be more aesthetically pleasing than vast expanses of a singular colour, shape or texture.

Soil Quality and Erosion Control

High-functioning landscapes start with healthy soil, and mass/mixed planting can play a key role in improving soil structure and resilience. Plants with varying root depths enhance organic matter by aerating the soil and preventing compaction.

Deep-rooted perennials, like Dianella caerulea and Lomandra longifolia, strengthen soil profiles while reducing erosion risks. This is particularly crucial in areas with heavy rainfall or steep gradients.

Another key advantage is the use of nitrogen-fixing plants, such as Hardenbergia violacea, in mixed planting schemes.

These plants replenish Nitrogen (which is air and water soluble) naturally, decreasing dependency on synthetic fertilisers. This sustainable approach aligns well with long-term maintenance and cost efficiency while supporting vibrant plantings. This is an under-rated landscape function that specifiers can use to reduce reliance on fertilisers.

For mass planting, groundcovers like Myoporum spp. offer dual benefits of soil stabilisation and weed suppression, further cutting down on maintenance needs.

Small to medium shrubs like Rhagodia spinescens and Westringia fruticosa provide layered height and texture contrast against strappy plants and low-lying groundcovers.

Climate Resilience and Sustainability

With more frequent extreme weather events and Australia’s inherently variable climatic conditions, designing for resilience is paramount. Mixed planting strategies are particularly suited to this challenge, as they combine species with differing tolerances to drought, salinity, and temperature fluctuations.

This strategic diversification helps ensure that if one species fails, others will continue to thrive, thereby maintaining the landscape’s functionality.

Plants like Callistemon viminalis  and Cenchrus purpurascens are used for their drought tolerance and durability in harsh conditions, making them ideal candidates for mass planting for minimal supplementary irrigation during drought.

Mixed plantings also support microclimates by combining shade-providing shrubs with groundcovers, which help retain soil moisture and reduce surface temperatures. By planning plantings with climate resilience in mind, specifiers can future-proof public spaces while reducing resource demands.

Amenity and Aesthetic Benefits

The visual and social benefits of mass and mixed planting are substantial. Public spaces designed with mixed planting often have dynamic layers of textures, colours, and seasonal changes, creating engaging environments that encourage connection with nature.

On the other hand, mass planting can provide bold, structured patterns that establish visual order and tranquillity, especially in high-traffic urban locations. Let’s face it, mass plantings are often easier to plan and maintain, as well.

A good mixed planting might include a tall tree like Luscious® Tristaniopsis laurina ‘DOW10’ PBR, a low shrub like Mundi™ Westringia fruticosa ‘WES05’ PBR, a flowering groundcover like Pink Fusion™ Scaevola humilis ‘PFS200’ PBR, as well as a couple of strappy plants like Baby Breeze™ Dianella ‘DCNC3’ PBR Intended, and Lady Tanika® Lomandra longifolia ‘LM360’ PBR.

Maintenance and Cost Efficiency

A common concern for specifiers working in public spaces is the balance between ecological ambitions and maintenance budgets. Fortunately, well-chosen plants can meet both needs. Low-maintenance species reduce intervention costs by requiring less irrigation, fewer chemical treatments, and minimal pruning.

Mass planting is particularly efficient, as uniform groupings share similar care requirements, streamlining routine maintenance. For example, a bed containing a mass planting of a singular Lomandra longifolia variety means that every plant in the bed shares the exact same needs (in theory).

On the other hand, mixed planting offers similar natural weed suppression through dense groundcovers and canopy layering, however where plants with differing maintenance requirements the maintenance can become more difficult.

A bit of horticultural knowledge from the specifier goes a long way to simplifying the maintenance schedule.

To make mixed plantings easier for specifiers, Ozbreed have been thinking about Machine-Efficient Biodiverse Installations (MEBI) plant lists, where the maintenance crew are able to chop the whole mixed planting down at the ground uniformly every few years.

MEBI plantings reliably bounce back from hard pruning, even when performed by maintenance operators lacking formal pruning education. More on this to come in the future.

Characteristics of Ideal Plants for Mass and Mixed Planting

Adaptability to Local Conditions

Species that thrive in local climates and soils are likely to succeed with minimal intervention. Always check climate and position info for all plants specified, and match them to the real-world conditions of the site. Hopefully this isn’t new information for you.

Low Maintenance Requirements

Hardy plants, such as Poa labillardierei and Carpobrotus glaucescens, are used for their ability to thrive without constant care, making them excellent choices for both mass and mixed planting schemes.

Ecological Benefits

Selecting plants that enhance biodiversity and soil health is key. Nitrogen-fixers like Hardenbergia enrich soils, and year-round flowerers like Chrysocephalum sustain local pollinators.

Aesthetic Appeal

Plants should complement the overall design intent. Bold, uniform species work well in mass plantings, while varied forms and seasonal interest are assets for mixed planting. Consider how colours, shapes and textures interact in mixed plantings.

Resilience to Pests and Diseases

Robust, pest-resistant varieties such as Shara Blue™ Lomandra ensure plantings remain healthy with minimal chemical intervention.

Climate Resilience

Plants like Rhagodia and Callistemon endure a range of conditions, ensuring that landscapes remain functional and visually appealing even under stress.

Top 10 Mass / Mixed Plants

The word ‘best’ is subjective, and depends on the functions you’re particularly interested in, but all of these plants are extremely high performing in terms of erosion control, soil improving qualities, and most are extremely beneficial for wildlife (with the notable exception being Lady Tanika® Lomandra which is sterile and is less attractive for pollinators).

Without further ado, here are out top 10 mass/mixed plants in no particular order:

• Lomandra longifolia ‘LM360’ PBR Trade Name Lady Tanika®
• Lomandra fluviatilis ‘LM380’ PBR Trade Name Shara Blue™
• Lomandra longifolia ‘LM604’ PBR Intended Trade Name Tanika® NEW IMPROVED
• Westringia fruticosa ‘WES04’ PBR Trade Name Grey Box™
• Myoporum insulare ‘MYIN01’ PBR Trade Name Ground Hug™
• Dianella caerulea ‘DCMP02’ PBR intended Trade Name Little Jess™ NEW IMPROVED
• Dianella caerulea ‘DBB03’ PBR Trade Name Cassa Blue®
• Dianella tasmanica ‘TR20’ PBR Trade Name Tasred®
• Rhagodia spinescens ‘SAB01’ PBR Trade Name Aussie Flat Bush™
• Westringia fruticosa ‘ WES05’ PBR Trade Name Mundi™

Daniel’s Wrap

For landscape specifiers in Australia, mass and mixed planting offer a harmonious solution to the complex demands of public space design. These strategies bring together ecological integrity, visual appeal, and practical functionality to create spaces that are sustainable and engaging.

Forward-thinking specifiers are moving away from mass plantings of a single species, and looking toward mixed plantings which often provide exponential ecological benefits. The problem is that by increasing complexity we can risk plant failures.

By opting for reliable high performers like those listed above, specifiers can be more confident that their designs will last the test of time in harsh climates that we expect to get harsher as the climate changes.