( CNN ) -- When is a garden not a garden ? When it 's an avant garden . Designers of the past -- who were concerned with verdant lawns , traditional flowerbeds and tasteful ornaments -- would barely recognize the experimental gardens of today . `` Garden design has always been quite a traditional discipline , says Madison Cox , a garden designer and part of the team behind a new book , The Gardener 's Garden . `` Gardens are in a constant state of flux , and you can only do what the plants allow you to do . So it changes less rapidly than painting , sculpture or architecture , as it takes longer to experiment . '' Plant vocabulary . There have been other restrictions , too . In the past , garden design was limited by the plants available , as it was difficult to access plants that did not grow indigenously . But now , says Cox , the `` plant vocabulary '' has increased . `` Go to any garden center in England , Italy , America or elsewhere , and you 'll find plants from all over the world , '' he says . This -- together with the influence of radical breakthroughs in the disciplines of painting , sculpture and music -- has allowed a new generation of gardeners to create spaces that owed more to the imagination than tradition . The birth of a new experimental art form . It started with experiments like Lotusland , an extravagant garden in Santa Barbara , California that was created in the latter half of the 20th Century by Madame Ganna Walska , an eccentric opera singer . It contains exotic plants from all over the world , set in fantasy contexts . `` It 's completely mad , '' says Cox . `` The section called the Blue Garden , for instance , has many blue plants and blue-colored slag from a Coca-Cola bottling plant on the ground . The effect is this weird , underwater , blue light , that is at the same time eerie and soothing . '' Similarly , Marjorelle -- a public garden in Marrakech , Morocco , that attracts about 730,000 visitors a year -- showcases plants that are almost completely devoid of vivid color , and resembles a world of grays , light greens and pale blues . `` The only color comes from things that are not natural , like painted surfaces and pottery , '' says Cox . Taking design to the next level . In Kent , England , the garden that belonged to movie director Derek Jarman eschews grass and traditional trees to embrace flotsam , weeds and found objects , creating a space that is in many ways closer to a movie set than a garden . Modern experimental designers have been taking things to another level . The Red Sand Garden in the Royal Botanic Gardens in Melbourne , Australia , resembles a martian landscape , complete with rock circles , curving escarpments and striking forms and foliage . However , modern avant garde designers are not completely free from all constraints . `` In today 's world , we have other pressing environmental issues , such as water conservation , '' says Cox . `` Designers need to consider what is appropriate to the specific climatic conditions they are working in . This is of vital importance . '' The heart of any garden . Ultimately , he says , a garden is a garden if it represents a retreat from the world . `` In recent years there has been an explosion of creativity , '' he says , `` but we have never lost that sense that garden is a paradise , a retreat from the world , and an alternative to our normal surroundings and chaotic lives . `` That has always been the point of a garden , and that will never change . '' One hundred years since the 'Golden Age ' of posters began . The enduring allure of steam trains : A nostalgic journey back in time . 9 maps that reveal London 's secret history , from Shakespeare till today .
The Children 's Garden features some of the most beautiful gardens from around the world . A new generation of gardeners are creating experimental spaces . Modern avant garde gardens are considering climate change and water conservation .