Edible Landscapes and Novel Crops

I am privileged to work as a lecturer and researcher at the Burnley Campus of The University of Melbourne, surrounded by historic gardens and an active field station dedicated to teaching and research. Many people remember our campus as Burnley Horticultural College when it was an independent college before it formally joined the University in 1996. This year is the 125th anniversary of a continuous horticultural education brand at Burnley and there will be a series of events throughout the year to mark the occasion.

Burnley has a strong tradition in training students to grow food through its urban horticulture courses. I’m lucky enough to run two subjects that teach food production for cities. I link these subjects to my Novel Crops Project which is identifying ‘new’ food plants for cultivation in Melbourne gardens, for example, Sweet Potato and Taro. The Project is trying to keep people excited about the idea of ‘edible landscapes’, gardens that look great and inviting but also provide food. Many of the plants we’re looking at could also be used in public parks and gardens and have great appeal across the community. We’re especially interested in ‘culturally appropriate’  species for diverse migrant and refugee groups whose interest in edible species from ‘home’ (as food and garden plants) is usually ignored by the mainstream.

In the Novel Crops Project we’re interested in perennial plants that are multi-functional. The best perennial food plants persist or reshoot in the garden once harvested, have more than one part you can eat, have outstanding aesthetic features, or provide other functions such as mulching. In short, we’re trying to capture the complex stories behind any given species, from the technical and scientific aspects of cultivation requirements to issues of yield, taste, nutrition and beauty.

How many species?

We grow around 20 novel crops including leafy greens including various tropical spinaches and other important species not normally associated with gardens in Melbourne, for example,. ginger and turmeric. Some of these species are well-known in supermarkets but not common in gardens; others are limited to migrant groups who cultivate them outside the mainstream of garden plants and vegetable gardening. Warmer overnight temperatures from climate change have helped some of these species perform better in Melbourne than they once did. As with most plants, however, many of these novel crops don’t like heatwaves above 40 degrees so there’s a limit to the benefits of climate change for even these warmth-loving plants. We’ve established a demonstration garden at Burnley to show off some of these crops in an edible landscape. So let me highlight here some of the outstanding crops we’ve investigated.

Oxalis tuberosa – Oca or New Zealand Yam

This non-weedy Oxalis species is widely grown in the Central Andes in South America, and in New Zealand. Small ‘yams’ are produced when days get shorter in autumn – from the equinox around 21 March. The plant has attractive clover-like foliage and is easy to grow from cuttings and tubers. Most importantly it is delicious and can be eaten raw or cooked. Although easy to propagate the long wait for tuber production requires patience and some planning and we’ve worked on how to make Oca growing a lot easier. My adventures in Oca growing are described in my blog at http://peopleplantslandscapes.blogspot.com.au/2014/05.oca-or-new-zealand-yam-harvest-how.html

Sweet Potato

Ipomoea batatas – Sweet Potato

Sweet Potato is now a familiar sight in Australian supermarkets, especially the orange Beauregard variety, but not many people realise that there are over 6000 varieties of Sweet Potato globally and that these vary greatly in terms of  colour, texture, growth habit and leaf shape. The leaves make a nutritious protein-rich spinach and are often cooked with coconut milk in south-east Asia. Sweet Potato grows surprisingly well in Melbourne given its tropical origin. We have grown huge amounts of tubers from around six varieties in different soil types across the city. Sweet Potatoes grow easily from cuttings and the trick to successful growing at our latitude is to induce slips from existing tubers ready for planting in mid to late November.

Hibiscus acetosella – Cranberry  Hibiscus

This sub-shrub Hibiscus is closely related to Okra and Rosella but is grown for crimson maple-shaped leaves used in soups, stews and salads. It’s widely grown and used for this purpose in sub-Saharan Africa, Asia and the Pacific. It has beautiful flowers but they won’t appear unless there is a very mild start to winter. The leaves have a lemony tart flavor and the plant as a whole is extremely attractive. It is very heat tolerant and survives dry weather well. It dies off completely in winter but can be perennialised by taking late summer cuttings, which strike easily. These may be kept in pots in a sheltered spot, ready for planting out in late spring.

Dioscorea alata – White Yam

White Yam is a deciduous, herbaceous climber and extremely beautiful. It has been cultivated in gardens in New Guinea for thousands of years. It produces big, gnarly, starchy roots ideal for baking and is an important staple in Africa, Asia and the Pacific. Its heart-shaped, glowing green leaves are the epitome of tropical lushness. Much to our surprise it grows exceptionally well in Melbourne.

Sechium edule – Choko or  Chayote

Chokos have been grown in Australia since the late nineteenth century and grow so well in the right climate that people often complain about the over-abundance of the relatively bland pear-shaped fruit. But don’t let this put you off because if you get the right variety, Chokos grow easily in Melbourne and produce edible shoots and leaves as well as the famous fruit, that soaks up the flavours of other ingredients when cooked. It’s native to the highlands of Central America and as a result is happiest in early to mid autumn when it puts on a growth spurt, sprawling over back fences and flowering and fruiting after equinox. It dies back in winter and then reshoots in spring as long as the soil is not too cold and wet.

Colocasia esculenta – Taro

Taro is an outstanding tuber crop, cultivated for thousands of years and arguably the first true agricultural/horticultural crop developed by humans. Through the Novel Crops Project we’re growing and trialling several varieties, from giant types popular in the Pacific Islands with metre-long elephant ears to smaller types grown in Asia. We have been impressed by their productivity and Taro deserves to become a standard edible landscaping crop. With sufficient irrigation they do well in difficult semi-shady spaces such as the side of houses. A clump of plants can be gradually harvested for their tubers or simply left for a year for their ornamental value. If exposed to frost the foliage will turn to sludge, but in my garden where they survive two frosts a year, they grow back vigorously from  early September onwards. Taro tubers are a source of densely packed carbohydrates, much less watery than potatoes and I have converted several people to their taste and texture.

Nelumbo nucifera – Lotus

In a city with such a rich horticultural history as Melbourne, it is surprising that Lotus doesn’t have a more established record of cultivation. Lotus is the sacred flower of Hinduism and Buddhism and grows naturally in water throughout India, south-east Asia, much of China and across northern Australia. It is therefore technically a native plant. It also has an edible rhizome popular in Asian cooking. In truth, through the Novel Crops Project we  grow it mostly for the extraordinary beauty of its big round, water- repellent leaves and also for its pink or white flowers and the dried seed pods, popular with florists. Many Lotus varieties grow well in Melbourne – all they need is full sun and a large pot with no drainage to grow in, preferably in heavy soil or ‘muck’. They die back in winter and re-emerge in mid to late spring.


Engagement projects

The Project now grows many of the plants discussed above with local government and community groups. We’ve established pop-up or permanent plantings at the Richmond Housing Estate, at the Carlton Neighbourhood Centre and at Dandenong Park in Dandenong. The City of Greater Dandenong is the most ethnically diverse municipality in Victoria. Our tropical edible landscape bed in Dandenong’s main park, grown in partnership with the council’s dedicated horticultural team, has proved very popular with local  communities who have never before seen their favourite food plants from ‘home’ present in Melbourne’s public gardens. The huge harvest of sweet potatoes from this planting last year was donated to charity.

This year we’re also excited about developing a horticultural training package for refugees and migrants at the Carlton Neighbourhood Learning Centre where members are keen to grow many of the ‘novel crops’ that we are proving grow relatively easily in Melbourne’s warm temperate climate.

Written by Dr Chris Williams

Published in the Friends of the Royal Botanic Gardens Botanic News, Winter Edition

Contact me at: chriscw@unimelb.edu.au

(Ed Note: This article was presented to the Friends as a talk in November  2015.)