Whilst the symbol-based planting plans discussed above undoubtedly achieve a naturalistic distribution of plants across an area, they are also complex and very time­consuming to lay out. It has already been noted that the majority of practitioners in this field either lay out the plantings themselves or supervise the layout of the plantings. It has also been noted in Chapter 2 that even in Germany, where this style of planting originated, examples in public landscapes are relatively rare and are generally restricted to former garden festival sites that have subsequently become public parks, demonstration sites or botanical gardens, as well as private gardens. Part of the
explanation for this could be the technical difficulty in implementing the plans, but may also be partly related to maintenance. Ironically, laying out plantings with such a strong naturalistic pattern may require ongoing maintenance to maintain that pattern and to prevent dominance by more vigorous species or weedy invaders. And this maintenance must be skilled and knowledgeable to enable the desired balance of structural plant types to be maintained. This is perhaps the biggest difference between ‘naturalistic’ styles and ‘ecological’ styles—whilst the former are maintained to be nature-like in appearance, the latter are maintained to be naturelike in function. Of course, the natural patterns in wild or spontaneous vegetation from which the inspiration for nature-like plantings are derived are much more a result of chance—plant distributions are related both to the random chance that a particular species is available but also to whether that species is able to establish and persist under the precise set of environmental conditions operating on that site. Natural patterns develop over time and, as has been discussed elsewhere in this book, are not static entities but continually develop and change over the years.

For this reason, significant strands of naturalistic planting design have not relied on precise planting plans at all, but have rather been based upon the specification of mixtures of plants that are laid out with varying degrees of randomness. This has been most widely applied to woody plantings but there is now also increasing interest in the use of mixtures of perennial plants.