Beds of flowering annuals are a traditional feature of public open space plantings. We spoke to Scott Watson about the costs involved.

ANNUAL BEDDING PLANTS IN PUBLIC OPEN SPACES

1. In some areas public demand for beds of annuals in public places is quite high. How costly is it to maintain these beds? Are the public aware of these costs?

It has been estimated by academics that a bed of annuals may cost around $300-$400 per square metre per annum to maintain. As a point of reference, this is typically 10-20 times the cost of maintaining beds of shrubs or ground covers. I doubt the public is aware of these costs as even open space managers are often unable to estimate the cost of maintaining annual beds!

2. Do you think the cost of maintaining annual beds is justified? Under what circumstances?

Of course there will always be circumstances where the cost is justified - but these situations are becoming fewer as resources dwindle for most public open space activities. Hitchmough (1994) suggests that annual beds can be justified in two situations. First, where significant users of a park are the middle-aged or elderly who pursue amateur gardening, and second, where the bedding will attract or encourage tourism. Clearly, both of these situations are limited in the broader picture of public open space.

While the broader community probably see the colour created by annual beds as an important traditional element within some open spaces, there is likely to be little objection where a cheaper substitute is used to provide a similar colour effect.

3. Is it possible to reduce costs and maintain acceptable quality?
In short, yes. On one hand the maintenance cost of annuals can be reduced through improved management, while on the other hand a less intensive approach to generating seasonal colour in the landscape can be developed. Increasingly we are seeing open space management being put out to tender, so costs are necessarily being reduced in this process.

Proper management of annual bedding will have a significant impact in reducing the costs of this landscape treatment. Firstly, the largest cost of annual bedding is that of labour so basic training is the most important starting point. Pre-planting weed control can have an enormous impact on the amount of post-planting maintenance where most labour is used. Seed of commonly occurring annual weeds such as Chickweed (Stellaria media}, Spurge (Euphorbia sp.) and Winter Grass (Poa annua) can be stimulated (through cultivation for example) and controlled prior to planting. At some point in the cycle of maintaining annual beds, the soil can be fumigated for a thorough destruction of the soil seed bank. While this latter activity is relatively expensive, it is possibly the most effective method of medium term weed control.

Basic mistakes commonly seen in post-planting maintenance include employees on their knees hand-weeding rather than the utilising a hoe or three pronged cultivator which are normally more efficient for annual weeds (hoes and cultivators are not normally used on perennial weeds). Correct tool selection and matching hoe size to soil type may also be important in achieving effective weed control. Unfortunately rates of weeding efficiency can be very variable - one of the downfalls in today's education system for on-ground horticultural employees in Australia is the lack of standards relating to efficiency in performing a task.

Design of the annual bed and planting programme can also lead to some reduced costs. Larger annuals may be more effective in competing with and controlling weeds, while direct sowing of annuals may be cheaper (although there is less control over the plant composition).

To greatly reduce costs of providing seasonal colour, other landscape treatments should be used rather than the continued use of annuals.

4. What are the alternatives to annuals for colourful displays?

There are several options available! The cheapest option would have to be mown turf with broadleaf 'weeds' that are allowed to flower, such as Cat's Ear (Hypochoeris radicata) Dandelion (Taraxicum officinale) or English Daisy (Bellis perennis). Flowering periods are limited, and the density of colour is rarely near that of traditional annual displays.

Herbaceous perennials can be used in several ways. Oehme and van Sweden (1990) in the USA have played a significant role in developing the use of herbaceous perennials and tussock forming grasses in bold patterns to provide colour through both flowers and foliage. This has also been popular in Germany and the Netherlands for some years, particularly for achieving the goal of nature conservation at the same time. Dunnett (1998) in the UK is currently investigating the use of directly sown annuals amongst a matrix of perennials as a method for providing dynamic colour. For example, one combination they recommend is Sedum 'Autumn Joy' oversown with Love-in-a-mist Nigella damascena. There have been many articles in the English journal Landscape Design over the past few years on various methods of creating wildflower meadows.

There has been some interest in utilising local native herbaceous perennials as floral bedding. Moreland City Council in Melbourne is likely to use indigenous plants for what was traditionally an annual display outside the Coburg Town Hall following recommendations by Ian Shears (1997).

Bulbs are another form of developing colour in the landscape. In cooler areas in country Victoria, Daffodils (Narcissus spp.) are a fantastically low maintenance method of providing massed winter colour along roadsides with little or no maintenance requirements.

Colour can also be achieved through other plant forms (such as shrubs or trees), hard landscape elements or perhaps even plastic flowers (why not?). However all of these do not express the same depth of seasonality that herbaceous material does.

Illustrations:
Above centre: A bed of primulas surround a Weeping Cherry in front of an Anzac memorial in Surrey Gardens, Melbourne.
Above right: Nemesias create a splash of springtime colour.

References
Dunnett, N. (1998) Dynamic meadows, Landscape Design, June, 1988.
Oehme W. & van Sweden, J. (1990) Bold romantic gardens, Florilegium, Melbourne.
Hitchmough, J. (1994) Urban landscape management, Inkata Press, Port Melbourne.
Shears, I (1997) Coburg Town Hall bedding: report on possible indigenous plant alternatives, Report to Moreland City Council.

About the Writer: Scott Watson is a part-time lecturer in landscape design and graphics and plant I.D. at Burnley College. He is also studying for his Masters in Landscape Architecture at the University of Melbourne. He does some work for Greening Australia from time to time, and is particularly interested in planting design with indigenous plants.

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