The Hedges: when gardening becomes art

In the creation of a garden, hedges are a fundamental, indispensable element, even if this does not reach large dimensions. The hedges cannot be missing both for the practical function they perform and because they enrich it aesthetically: in fact, the hedges give the garden a harmony and a style that makes it a true work of art.

But what is a hedge?

Commonly, by hedges we mean plants, especially evergreen ones, raised in a precise geometric shape, obtained by periodically pruning the hedge. However, this concept of a hedge is particularly reductive, first of all because there are various types of hedges in relation to the needs they have to meet. In fact, they effectively meet a plurality of situations, from the more general (defensive, windbreaks, etc.) to the specific and particular (hiding an unpleasant view both inside and outside that garden). Precisely in order to meet these numerous requirements, the choice of species that can be used in the formation of gardens, parks and green areas has become much broader and more diversified.

Returning to the initial question, the term hedge must be understood in a very broad sense, not only in relation to function, but also in relation to the very wide range of plants that can be used. These plants can also be very different from each other in terms of size and habit, whether they are evergreen or deciduous, whether they have thorns or not, etc. Man’s intervention can also manifest itself in different ways: by giving the plants a precise shape or by leaving them free to grow and assume their own habit.

All these different plants, with a final form that may be natural or desired by man, are brought together in the group of hedges because together they form a ‘barrier’, they create a ‘separation’ with linear and vertical development. The hedge must therefore be understood as everything that divides, divides or separates. The words ‘separation’ and ‘barrier’ (a term used especially for medium to tall hedges) clarify both function and use; it also explains why this group also includes plants that cannot be kept in shape, such as the agave (Agave americana).

Hedges were created to enclose and isolate certain areas, but their function has been enriched with aesthetic meanings, to the point where they have become true works of art. In other words, hedges have become the meeting point between man and nature. In fact, man was no longer content to use hedges only at the edge of his property for ‘defensive’ purposes, but wanted to make them part of the garden, giving them a new task and adopting, for the plants used, absolutely original forms obtained through admirable chiselling, thus giving nature a whole new order and life.

All this must not lead one to think that this type of intervention is violence to plants, a distortion of nature to realise man’s selfish interests. Rather, man has only been able to carry out these works after a careful knowledge of plant biology. Indeed, if man wants to give the hedge an unnatural form, he uses plants whose main characteristic is that they are strongly bushy and particularly tolerant of pruning. Furthermore, continuous pruning strengthens and reinforces the plants, so that their branches are less prone to breakage.
Man’s great interest in these ‘hedge’ plants has not been limited to cultivation care or periodic pruning; he has also selected new, stronger and disease-resistant varieties that are also particularly beautiful to meet the needs of every garden.

THE CLASSIFICATIONS OF THE HEDGES

1) According to human intervention
 a) natural
 b) artificial
 b1) free
 b2) polite

2) According to function
 a) defensive hedges
 b) ornamental hedges
 c) windbreak hedges

3) According to the height

The hedges have been grouped and classified into a few broad categories.
The first of these is based on the way in which human intervention manifests itself in the planting, formation and maintenance of hedges.
The second classification considers the function that the hedge must perform. This classification will include defensive hedges, ornamental ones and windbreaks.
Finally, hedges can also be classified according to their height. We will thus have woody border hedges, medium-sized hedges and tall hedges or hedges; the latter exceeded in height only by those windbreaks.
These last two subdivisions are not based only on the use made by man, but, first of all, on the study of the characteristics of plants; characteristics that are the basis of their use. However, the use that can be made of a plant is strictly related to the size that the plant can reach; in this sense these last two classifications interpenetrate each other. For example, it is clear that a defensive hedge must have an adequate size. These classifications will also give us the possibility to list and treat many species of plants used to make up the various types of hedges.

1) CLASSIFICATION ON THE BASIS OG HUMAN INTERVENTION

Hedges can be divided into two large groups: natural and artificial ones.
The former are mostly devoid of any human intervention and their origin is always spontaneous, while the latter are established by the will of man. Artificial hedges are in turn divisible into two subgroups, consisting of free and educated hedges.

 a) The natural hedges they are those that arise spontaneously in marginal areas of the countryside, left uncultivated by man, such as the edges of the roads, the drainage channels of the land, or on the borders of the land itself. It is probable that in very ancient times these hedges were left to grow to constitute, with the boundary stones, a very evident sign of the division of properties, materially hindering those who wanted to access them, and constituting the first example of a “hedge”, from which all the others have evolved. These hedges, made up of plants typical of the flora of the Mediterranean area, or which have perfectly adapted to it, multiply easily and can become intrusive. They are often thorny and maintain a deterrent function towards strangers, but they can also be left to grow to consolidate landslide embankments, especially if they have a strong root system as in the case of Robinia pseudoacacia. Among these spontaneous plants I remember the bramble (Rubus fruticosus), the thorn-crucifix (Paliurus spina-christi), the blackthorn (Prunus spinosa), the hawthorns (Crataegus monogyna, oxyacantha) and in southern Italy the prickly pear (Opuntia ficus-indica).

b) The artificial hedges they are planted by man according to his own taste and the function they must perform. Generally this type of hedges are formed by plants of a single species because, if different plants or plants belonging to different species were placed on the same row, at a short distance from each other, it could create an unpleasant aesthetic appearance. In fact, for example, the coloring of the leaves of the common cypress and the oriental thuya differ in tone, and this marked difference stands out particularly, even from a distance, if we place these two plants side by side in a hedge.
Furthermore, it has an unpleasant effect when deciduous essences, such as Maclura, are planted alongside other evergreens, such as Pyracantha.
It is not advisable to form hedges with plants of different kinds also for physiological reasons: in fact some plants have a higher growth rate than others. Thus the former, vegetating more rapidly, would alter the harmonious vision of the whole and would certainly occupy the space of the plants with a slower growth rate, up to overwhelm them and make them succumb. A typical example of plants with different growth rates is the pittospore and the glossy privet, which do not have to grow together for this very reason, even if the color of their foliage coincides and would make them associate.

Artificial hedges are divided into free and polite.  

b1) In free hedges man is limited to the plant, after which the plants are free to develop in height and width, without man having to intervene with pruning to contain them. This category includes windbreak hedges. Even in gardens we can meet free hedges in the form of isolated bushes, formed by plants of modest height.

b2) In polite hedges human intervention is more marked; in fact it manifests itself with periodic pruning, designed to keep the plants in a specific shape, with weeds eradication, periodic fertilization, watering during the dry season, pesticide and fungicide treatments if the animal attack or the fungal infection is so serious as to compromise the aesthetics and / or the lifespan of the plants. This group includes all cultivated hedges, even if they have different functions such as defensive ones, those for borders etc., which will be treated later.

2) CLASSIFICATION BASED ON THE FUNCTION THAT THE HEDGE MUST PERFORM

The functions that hedges must perform are essentially two: that of enclosing and that of decorating; each of these two functions is fulfilled by different plants with different characteristics. In some areas particularly beaten by winds, the need has arisen to place high protective barriers; this barrier is called a windbreak.

a) THE DEFENSIVE HEDGES

The oldest function is undoubtedly that of fencing a private area, to prevent the entry of strangers. Hedges that perform this function are called “defensive”. For this function we have chosen plants that have robust thorns such as Maclura aurantiaca. This plant does not belong to the Italian flora but has adapted well to the Mediterranean climate, and is often used for defensive purposes due to the presence of strong thorns and its rusticity. Another plant used for defensive purposes is certainly Pyracantha, an evergreen, rustic plant with obviously thorny branches. This plant also has a certain ornamental value because, if grown in a natural form, it produces very decorative red berries that remain on the plant from September to March; if, on the other hand, it is raised in a forced form, or subject to frequent pruning, the production of berries will be much lower. The Crataegus are also used to build defensive hedges, but also for ornamental purposes as they have very decorative flowers and small reddish fruits that remain on the plant even in winter. The European hawthorn (Crataegus oxyacantha) belongs to this genus of plants. It is a rustic, deciduous plant, and obviously with thorny branches, which resists well to the fumes and gases of the urban environment, and therefore lends itself to being cultivated also in the city.

b) THE ORNAMENTAL HEDGES

The hedges also have another function, the ornamental one; these hedges are created only for an aesthetic use. We can say that the hedges are the stroke of the landscape architect’s pen. In fact, the land where the hedge will rise can be considered as a hypothetical white sheet on which the hedges will draw, for example, long green corridors designed to divide the garden into several sectors, within which there could be other hedges to delimit the flower beds, making them the drawing is more evident. The flower beds could be isolated and unique, forming large flat geometric figures, for example, or they could be symmetrical with respect to other flower beds, etc. The flowerbeds could be used as mosaic tiles: the set of their designs can give life to a new and complex figure.
The hedges can be designed to guide the eye towards particularly valuable areas of the garden, as happens, for example, when in the center of the garden itself there is a fountain with water features, which, due to its position and beauty, has been designated as the most important point of the garden. The human eye will be guided towards it by the paths bordered by hedges, which will start from various points in the garden to all converge towards the fountain. The hedges that draw a garden are necessarily made up of small plants, so that the eye can easily grasp the intertwining of the lines, the geometries and therefore the overall effect. The hedges can also become the “closing” element of the garden: in this sense the hedges surround the garden not to prevent access to strangers but to prevent the eye from “leaving” the garden and getting lost.
These hedges necessarily have larger dimensions than the previous ones, so they are built with different plants with higher development. They can be considered the ideal setting for the garden. The hedges also give a small garden that regularity, that geometric order, which constitutes the right combination of art and nature.
The ornamental hedges must not be understood only as a play of lines, symmetries and flat geometric figures; in this meaning must be included also and above all solid figures, geometric and otherwise. Wonderful prunings have transformed the plants into three-dimensional figures that give the garden a fantastic and classic look together. The creation of solid figures using plants has given life to a real art: topiary art.

Garden of the villa Gamberaia – Parterre – Settignano Florence

The most used plant to obtain “flat geometries” is undoubtedly boxwood (Buxus sempervirens). This species of boxwood is a plant that has a very slow development speed, never reaches large dimensions and for these two reasons it lends itself very well to form ornamental hedges of modest size, such as those found at the edge of flower beds or that delimit paths. or driveways. Boxwood is also widely used because, thanks to periodic pruning, it assumes a very compact habit and is devoid of thorns. In fact, it plays a leading role in the history of Italian gardens.

Among the plants that can be used to frame the garden to form solid figures I remember the yew, the holm oak and the cypress.
The plants to be used to make up these types of ornamental hedges must always be chosen among those of the Italian flora such as boxwood, laurel (Laurus nobilis), yew (Taxus baccata), holm oak (Quercus ilex) etc.

c) THE WINDBREAKS

Plants that can be used to build windbreaks must have certain characteristics. They are: rapid development, compactness, elasticity and height. The height, together with the elasticity, is certainly a very important quality, because the width of the coverage offered by the windbreak depends on it. In fact, the protected area is equal to ten times the height of the windbreak. This function is performed more by rows of trees than by actual hedges. A fairly common wind barrier is formed by rows of Italian cypress (Cupressus sempervirens). This plant has a compact crown, of good height and above all a fair elasticity, a basic feature to resist even the most impetuous wind.

The Italian cypress can also be used to build tall hedges because, like many species of cypresses, it tolerates pruning quite well. Many other plants of the Cupressaceae family are used to form hedges or high barriers; among these the Leyland cypress (Cupressocyparis X Leylandii) stands out. This plant is particularly rustic, very resistant to pruning and indifferent to any type of soil. Furthermore, among its peculiarities there is a high rapidity of growth.

We can also mention the Monterey cypress (Cupressus macrocarpa) as a windbreak tree, which is mainly used in coastal areas due to its resistance to brackish wind.

In marine areas the Eucalyptus is equally widespread as a windbreak tree, both for its rapid growth and for its resistance to brackish winds, and, above all, because near the sea the temperature remains mild, an indispensable aspect for this species, which can not stand too intense cold.

In many areas of Italy it is common to use cypress poplar, which is a very common variety of black poplar, to create windbreak barriers. This plant is called “cypress” poplar because it has a columnar bearing, branches very close to the trunk and therefore a very compact crown, reminiscent of the common cypress. It also has in common with the cypress the flexibility of the trunk and a good height. Cypress poplar is a fast growing plant that thrives and develops especially in constantly humid areas.

3) THE CLASSIFICATION BASED ON THE HEIGHT OF THE HEDGES

A further subdivision of the hedges is based precisely on the height of the hedges themselves: low or decorative hedges and high hedges or hedges. In fact, when the hedges do not reach forty centimeters in height, we should speak more precisely of woody border. The woody borders are made up of plants that do not reach great heights per se, such as boxwood, and must only fulfill an ornamental function. The difference between wooden borders and hedges of modest or medium height, on the one hand, and tall hedges or hedges, on the other, lies in the fact that the former allow the observer to dominate them, given their modest height, while the latter have precisely the task of closing the view on what is present “beyond”.

Among the species most used to build woody borders we remember Mahonia, Berberis thumbergi atroporpurea, the euonymus (Evonymus), lavender (Lavandula), Santolina chamaecyparissus, thyme (Thymus vulgaris) etc.

The high hedges are made up of plants that in nature have a bearing of several meters, such as the holm oak (Quercus Ilex), which easily reaches 20-25 meters in height with a crown diameter that can reach 15.

Dates these characteristics, it is self-evident that it will be used for large hedges that can reach 6-8 meters or more, or to form isolated solid geometric figures such as truncated cone or spherical, dimensionally considerable.

Among the plants that are often used to build this type of hedges, the cypress and cherry laurel (Prunus laurocerasus) stand out. The latter plant is widely cultivated in urban areas because it tolerates polluted environments.

The cherry laurel grows quickly and is used for hedges that can reach 3-4 metres in height and more. The cherry laurel, like the holm oak and cypress, is an evergreen plant. Hedges with ornamental value can be created with these plants: for example, they can be used to create real green walls at the edge of the garden, to frame the garden itself, or to create large isolated figures. But to achieve these effects one must have a large garden, and suitable means to reach the top of the plants.

The Hedges: when gardening becomes art (Part 2)
The Hedges: when gardening becomes art (Part 3)
The Hedges: when gardening becomes art (Part 4)

BIBLIOGRAPHICAL REFERENCES 
– AA.VV. “THE GREAT BOOK OF FLOWERS AND PLANTS” Selection from Reader’s Digest – Milan – 1978
– E.Susini “MY FLOWERS AND MY GARDEN” Edagricole 1987
– E. Susini “HEDGES AND BORDERS” Edagricole
– E. Susini “GUIDE TO THE DESIGN OF SMALL GARDENS” Edagricole
– M.G.Bellardi “MAL BIANCO SU LAUROCERASO” Taken from “GIARDINI” May 2005
– M.Ferrari “LIMANTRIA OR BOMBICE ODD” Taken from “GIARDINI” May 2005
– M.Ferrari, A.Menta, E.Marcon, A.Montermini “DISEASES AND PARASITES OF FLOWERING, ORNAMENTAL AND FORESTAL PLANTS” Edagricole
– M.Ferrari, D. Medici “TREES AND SHRUBS IN ITALY – recognition manual” Edagricole 2003
– L.Crespi “BONSAI – practical guide to art and cultivation” Fabbri editori 1989
– G.Oelker “FLORICULTURE HANDBOOK” Edagricole 1957

Paolo Pecchioli, Agro-Technician, holds a qualification as a horticulturist-floriculturist. He currently holds the position of Technical Assistant at the Agricultural Technical Institute in Florence.

USEFUL LINKS

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http://it.wikipedia.org/wiki/Siepe
http://www.rivistadiagraria.org 
http://www.giardinaggio.it/speciali/Siepe/Siepe.asp
http://www.vivaioclorofilla.it/html/giardini_isegreti.htm