The purpose of this study is the development of a landscape design methodology based on the use of a Cellular Automata (CA) algorithm in order to introduce the plant-plant interaction factor in the plantation design of a site. This design methodology introduces the relations between neighbouring individuals of different species as parameters of the project. These parameters are codified in order to define the Cellular Automata rules. Parameters related to the growing and morphologic characteristics of the species but also programmatic and aesthetics parameters of the project may be introduced as rules that influence the behaviour of the CA algorithm. The algorithm developed it is called NNB-CA (Natural Neighbouring Behaviour Cellular Automata) and it is based on the original John Conway’s “Game of Life” CA. The design methodology takes in account site conditions and is developed in 2 phases. In the first one, starting with a list of species, a preselection of them is done taking into account parameters of the site and defines which species are able to populate on each area of the discretized site. In the second phase, the CA algorithm is run applying the relational rules with the selected species. This iterative process is applied until it reaches to an equilibrium state. Rules related to the competition between species according to their growing characteristics are studied comparing an analog/natural evolutive process using rapid development plants and the correspondent digital process that simulates the analog one.