What grows up must come down ... the recent trend to smaller plants

By Gabrielle Stannus

The traditional notion of a garden space in Australian cities has changed greatly over the last decade or two. In the “noughties”, the McMansion phenomenon saw the development of over-sized houses on under-sized blocks, leaving little room for plants. Fast forward to 2018 and the number of smaller gardens is increasing as our major cities grow more vertical. Mark McCrindle, from McCrindle Research, says that over one-quarter (26%) of all Australian dwellings are now medium or high density, and almost two-fifths (43%) in Sydney and Melbourne 1 . In Australia's largest capital cities, medium and high density dwellings account for two-thirds of all new building approvals for housing. Gardeners are now planting on balconies, courtyards and increasingly smaller blocks and increasingly looking for more compact plants to put in these spaces.

Ricky Hayward is one designer working in this space. Together with Gayle Benchley, fellow Diploma of Horticulture student at the Swinburne University of Technology, Hayward designed ‘Retro Urbana’, a compact edible garden. ‘Retro Urbana’ was showcased in the Avenue of Achievable Gardens at the recent Melbourne International Flower and Garden Show. Each garden in this competition represents an average balcony garden or a very small courtyard garden and is five metres wide by three metres deep.

Hayward and Benchley wanted to show that small spaces can achieve more functionality and productivity than otherwise thought. They and other garden designers are not only selecting smaller plants, but also cultivars of bigger plants manipulated to be smaller. More than twenty edible species were planted in “Retro Urbana”, including Laurus ‘Baby Bay’, Malus ‘Gorgeous’, Citrus reticulata ‘Imperial Mandarin’ and Citrus x limon ‘Eureka’. Prostrate forms of rosemary and thyme softened paving and edging.

Hayward says columnar apples are a great way of achieving reasonably high yields whilst allowing for tighter planting, perfect for small spaces. He would like to see more fruit trees in columnar form, believing they would help to increase the popularity of edibles in small urban spaces. Hayward is not averse to ornamental species either, suggesting that small compact magnolias and crepe myrtles would work well as low formal and informal hedges. “I know there are already dwarf versions of these (crepe myrtles), but the new Diamonds (in the Dark) range would be great in a dwarf cultivar” says Hayward.

Angus Stewart, well-known horticulturalist and broadcaster, has experienced the demand for smaller plants first-hand. “With regard to kangaroo paws, which are the main crop I breed, there is a constant world-wide demand for cultivars less than 40cm in height” says Stewart.

For plant breeders like Stewart, the demand for more compact cultivars is largely driven by the companies that distribute new plant varieties. These companies service growers responding to demand from retailers such as Bunnings and their overseas equivalents such as Home Depot in the United States.However, breeding or selecting your own proprietary varieties may give your nursery a point of difference. Growing more compact plants may offer other benefits for your business. Smaller plants may mean you can fit more in your greenhouses and a uniform compact habit can also mean easier management.

Stewart is currently working on dwarf Kangaroo Paw species including Anigozanthos humilis, A. onycis and A. gabrielae. Tissue culture techniques such as embryo rescue have helped to make it possible to cross breed species that would not normally cross by simple cross pollination techniques. Stewart has also found it productive searching in the wild for naturally compact forms within genera such as Banksia and Callistemon. Selection from wild plant populations needs to take the grower's needs into account as well as the end consumer. Stewart recommends looking for traits such as ease of propagation, prolific branching, long flowering and colourful foliage as well as compactness.

If looking to breed more compact plant varieties, Stewart recommends working at a scale that is cost effective for your business. He highlights the work of other Australian growers, including Jon Steeds from Sustainable Natives Nursery who is breeding compact native finger limes. “Careful research of the best possible genetics to fit your production, distribution and consumer needs is vital to your business” says Stewart. Watch out for “sports”, genetic mutations that occur spontaneously, and seedling variations in your nursery. Many new cultivars have arisen this way and they can potentially generate significant royalties to the originator. Look far and wide for new varieties to introduce to the Australian market, but remember that most modern cultivars bred overseas are not always suited to Australian conditions.

Those of you unable to capitalise on this trend can take heart as Stewart concludes that although smaller plants are currently in demand, there will always be room for taller species.

Useful Links

Avenue of Achievable Gardens: http://melbflowershow.com.au/show-features/achievable-gardens/
Gardening with Angus: https://www.gardeningwithangus.com.au/
Rick Allen Designs: http://rickallendesign.com.au/