Waterhouse participated fully in the 1920s and 1930s expansion of gardening as an art form and way of life. His view always and everywhere combines a scholarly internationalism with unflinching aestheticism. In
The Home in 1926 he published "Gardening as an Interpretative Art", illustrated with photos of his own garden by Cazneaux. His argument was elaborated and refined in "Domestic Gardening as an Art" in 1943. Annual and perennial flowers were not enough to sustain the garden as a work of art. Texture and form, not colour alone, were stable enough to support the symphonic repetition and variation of garden elements. Garden rooms formed by walls and hedges should be provided with the "furniture" of pots and geometrical shrubs — juniper, hydrangea and camellia. Larger pieces of "furniture" were provided by classical or oriental temples at the end of sandstone paths. The "floor covering" of the garden room was a well made lawn. Its role in structuring garden space should not be confused by island beds but emphasised by well-planted borders. were severely devalued as "too scraggy" for a Waterhouse design. By 1943 the only rose bush he recommends for Sydney is 'Cramoisi Supérieur' for its combination of bright colour and firmly rounded form. The
Lombardy poplar, on the other hand, had everything Waterhouse admired in shape, texture, colour and sound. Starting at Eryldene, many of his landscape designs were marked by formal rows of poplars — often closely planted as a screen. :He looked forward to the day when this school of landscape architecture would be established, where people could go for inspiration and for effective training in the work that was now being done by amateurs. It was a dream of the future, but he hoped that it would be realised. In this and other ways he was instrumental in founding the profession of landscape architecture in Australia. Overemphasis on cottage gardens had detracted from the "dignity and personality" of trees, especially Australian native trees, in the landscape. In a scheme for the McMaster Building at Sydney University, he specified a row of poplars to stand opposite the façade, matching its height and width, closed off at one end by five
Coral trees with flowers to match the bricks. Waterhouse was also responsible for planting what became the well-loved and iconic
Jacaranda tree in the
University of Sydney Quadrangle. With the encouragement of the Vice-Chancellor, Waterhouse redesigned and replanted the grounds of the University of Sydney 1925–1949. He redesigned the garden around the
Royal Prince Alfred Hospital and made designs for the
University of New England. When the State Governor moved to Canberra as
Governor-General of Australia, Waterhouse spent many hours at
Yarralumla discussing the landscaping with
Lady Gowrie. Sixteen years later he dedicated a camellia to her, one of his "eight or nine really good varieties". His last book (with Norman Sparnon) was published when he was 87. It explores the use of camellias in
ikebana, on which his wife Janet was an acknowledged expert. ==Camellias==