Creating a beautiful flower garden

The English flower gardens that Australian travellers continually hunger for were created in the middle of the last century, and reached their ultimate expression at Lawrence Johnson’s Hidcote garden and Vita Sackville-West’s Sissinghurst castle. With an extraordinary selection of perennial flowering plants that thrive through frosty winters and coolish summers no country in the southern hemisphere (except perhaps New Zealand) is so blessed with good consistent rainfall and cloudy skies that sharpen the flower colours to create unforgettable floral impacts.

However there are many garden adaptations that will lift Australian spirits despite our intense heat, poor soils and water limitations. Many of Australia’s native plants are of course perfectly adapted to extreme heat and drought. Over thousands of generations our native shrubs, both low and medium sized, have survived by evolving woody stems.

These shrubs have tough foliage and flower mostly in the cooler months of winter and spring. Their virtue is their evergreen foliage and ability to survive in soils low in phosphorus and carbon. However very few have the spectacular summer flowers of northern hemisphere herbaceous perennials such as delphiniums, lupins, poppies and hollyhocks that have soft, fleshy foliage spurred on by extreme cold and adapted to more fertile soils. Herbaceous perennials retreat underground in winter thereby building up energy stores for rapid and spectacular flowering in summer.

This article is not meant to denigrate our magnificent and spectacular wildflowers but simply point out that because they flower too early – just as tulips do – they are largely unsuitable plants for our summer gardens. Tulips of course are unsuitable for cultural reasons because they need dry soil in summer when they go into dormancy, but perennials with their rapid growth need watering which causes the tulip bulbs to rot.

Fortunately there are still hundreds of perennials that adapt well to dry summers and moderately cold winters. Just as ninety-nine percent of the vegetables and fruits we eat such as apples, strawberries, tomatoes and potatoes are exotics introduced to meet our food needs, the same is true of most of the flowers we grow in our gardens such as tulips, lavender, rosemary and lilies.

We call these modern perennials because they are heat tolerant and don’t need staking. These are permanent plantings with strong form above the ground, unlike short lived annuals that leave gaps after flowering and empty beds that weeds invade.

Perennials are manoeuvrable in the sense that they can be dug, divided and replanted. Most will live for 3 to 5 years, and some for decades. Because perennials are soft, fleshy (and not woody) and have soft green colours compared with our natives they have cooler textures and provide spectacular flowering throughout summer, not just in spring.

By choosing drought tolerant forms that don’t need staking these so called ‘old fashioned’ cottage flowers are the ideal solution for an Australian summer flower garden. Very few natives have the perennial form that fits within a perennial border.

Herbaceous perennials have annual flower stems and long-lived perennial roots. Their flowers and foliage die back during winter as the plant retreats underground to survive the cold. The foliage and flower stems emerge again in late spring, growing rapidly to begin flowering because they come from countries with much shorter growing seasons (Cold Zones 6, 7, 8). They have to flower and set seed months earlier than in Australian cities (Cold Zones 9, 10, 11).

Unfortunately Australia has a tiny range of herbaceous perennials compared with other continents. As the climate gets hotter, the woody stems of sub-shrubs predominate. Similarly in Mediterranean areas woody stemmed rosemary and lavender predominate. There are extensive selections of Australian herbaceous perennials in our frosty alpine areas but they translocate poorly in lower altitude coastal areas where our cities are located.

You may be aware, if you visit the gardens of St Erth or Heronswood, that you rarely find modern bedding annuals in our gardens. We avoid them because one of the lessons of colour is that it is a potentially dangerous tool, to be used carefully.

Enlarged flowers on plants are a “horticultural floral obesity” to be avoided. When used as true carpet bedding softened by a green lawn, pleasing impacts can be achieved – but rarely in the hands of inexperienced suburban gardeners.

Most annuals, particularly in the USA come in mixed colours – RED WHITE BLUE – which are their national colours. But like a neon sign that draws the eye, these are the colours our eyes rapidly tire of.