A garden has always been an interesting and masterly synthesis of geometric or fantastic realities and plant elements skilfully combined one with the other, thus representing a privileged place for experimentation of the artistic sense and planning wits in all civilizations. The problem of preserving and restoring historical gardens is particularly complex, because in these environments the vegetation component is integrated and permeated within the architectonic part, producing actually green monuments in the open air. It has been correctly affirmed several times that a garden is a living work of art and, therefore, its preservation and restoration cannot neglect biological and genetical laws of the plant world. Though one must consider more general aspects on the safeguard of cultural heritage, a complete filing and study of the green area for any kind of maintenance, preservation, requalification and restoration activity is essential. Especially in cases of a seriously compromised areas, it is necessary to give a particular attention to all architectonic, vegetative, hydrological, and structural elements that characterize the historical garden, along with an examination of the visual and functional connections with the surrounding landscape. In fact, the knowledge of all elements of the gardens cannot be irrespective of an exact comprehension of the territory in which they are merged and in which they were created. Besides the collection of historical information and archive documentation, a correct knowledge of the territorial unit enclosing the garden and the immediate surroundings is necessary. The survey of the vegetation -though objective difficulties may exist because of natural growth, developmental and progressive deperishment processes of the plants- can provide interesting hints about the definition of the most convenient management and restoration strategies to apply. Sometimes it could be necessary to introduce green coulisses or climbing plants so to hide territorial alterations, caused by buildings, factories, electric lines or roads that change important landscape views. A further problem, is also represented by the disappearance of internal views and perspectives, because of an excessive growth of the vegetation, that hampers the perception of depth, colours and contrasts, with a visual and psychological damage for the park, since the deep message conveyed by the garden and the chances to stimulate feelings and emotions fade away. In these cases, correct and scheduled prunings, considering plant canopy architecture can be useful. A reason to hope in a more efficient preservation of historical parks and gardens is undoubtfully represented by the growing interest towards these themes at an academic level, and also among professional operators, such as agronomists and forest engineers, who were once working only sporadically in the field of the management and restoration of historical gardens.
Keywords: historical garden, knowledge, safeguard, exploitation, filing, vegetation restoration