For clients with more modest means, Walling's approach was more relaxed, relying on curving lawns and garden beds to give the illusion of greater space. But rarely were there no stone walls or other structural features. Whether the garden was big or small, she created a succession of pictures. Her handling of space, contour, level and view was brilliant. Equally impressive was her mastery of plants and their visual and ecological relationships. Her gardens were clothed by a soft and consistent palette of plants. She favoured greens and used other colours sparingly, mostly in pastel tones or white. For many clients she produced an exquisite water-colour plan of the garden as a means of conveying her proposals. Most of her gardens were constructed by Eric Hammond. Walling often provided the plants from her own nursery and was frequently on site giving instructions and helping with the physical labour.
By the 1940s Walling's was a household name and she capitalised on her popularity by publishing four successful books: Gardens in Australia (1943); Cottage and Garden in Australia (1947); A Gardener's Log (1948); and The Australian Roadside (1952). A further monograph, On the Trail of Australian Wildflowers, appeared posthumously in 1984. Several more manuscripts were unpublished.
Her influence on C20th gardening in Australia was enormous. The visual impact of the hundreds of gardens she created, her extensive writing, and the respect she commanded from those with whom she worked, including Glen Wilson, Ellis Stones and Eric Hammond, had a considerable effect on the next generation. In the 1980s and 1990s she was to become almost a cult figure for many Australian gardeners and a number of books were published about her work.
In the mid-1940s Walling had developed a particular interest in native plants; she had begun using them in domestic gardens in the 1920s. An early and active conservationist, she joined battles to protect the natural environment and crusaded for the preservation of indigenous roadside vegetation. She was an outstanding photographer who always took her camera on her extensive travels. Classical music was another of her passions.
Miss Walling was not a person to be taken lightly. On site, dressed in her customary jodhpurs, jacket and tie, with strong, handsome features, she was energetic, determined and demanding. These character traits often provoked conflict, especially with some of her wealthy male clients. Yet she was also generous, fun loving and good company, attracting many loyal admirers and friends. By 1967, tiring of the characterless suburbs advancing towards Bickleigh Vale, she moved to Buderim, Queensland, to be in a warmer climate and near to her niece Barbara Barnes. Always single, Walling maintained a close relationship with Lorna Fielden, a teacher forwhom she had designed a house and garden at Bickleigh Vale. Fielden also moved to Buderim.