When you want to create a garden in countries where rainfall is absent during several months of the year, like ours, you can not ignore irrigation.
Our climate is in fact characterized by long and dry summers during which the survival of plants is put to the test. Even if we want to use Mediterranean species and therefore suitable to withstand dry periods once they reach maturity, we must consider that for the first two years after planting, all plants need to be watered more or less frequently.
We must not be fooled by what happens in nature, where plants suitable for a given place survive without any human intervention.
This happens mostly through a process of natural selection, whereby only a small percentage of the seeds take root and, among these, only a small part reaches maturity as adult plants.
In the garden obviously we cannot afford to lose most of the elements implanted and therefore we must necessarily have an irrigation system to facilitate its engraftment.
The alternative is to water the plants manually, but this implies a considerable effort in gardens of large size.
Gardens without irrigation
Nevertheless, it is possible to conceive the realization of a garden without irrigation under certain conditions.
The first one is the use of species particularly suitable for dry climates, the so-called xerophilous plants. These plants do not like water during the summer period, since they go into vegetative rest in these months unlike the winter ones.
These are obviously purely Mediterranean plants, which give the garden a very specific character. So you have to partly adapt your tastes to what you can do without water.
A second condition is to put in place the plants in the autumn period. In autumn the plants of our garden live a second phase of growth after the months of summer rest.
Thanks to the cooler temperatures and the still long days, the plants put in place during this period have the opportunity to settle in their environment and then meet comfortably the cool months of winter.
During the following spring the plants will then continue to root and take complete possession of their environment: they will therefore be ready to endure the hottest months and the greatest stress having two vegetative cycles behind them.
So it will be enough to water during the first warm season at intervals of about two or three weeks and then let the garden evolve without watering.
A third essential condition if you want to avoid an irrigation system as part of the garden, is to give up the turf.
The so-called English lawn is typical of a climate very different from ours, characterized by temperatures that are always relatively mild and constant rainfall throughout the year.
Despite the fact that in our latitudes we use more suitable mixtures for our climate consisting mainly of ‘Festuca arundinacea’ and ornamental varieties of ‘Cynodon dactlyon’ , the turf still needs a considerable water supply.
In our country, apart from exceptions such as mountain areas, the lawn needs about 4 or 5 liters of water per day per square meter, at least in the first season.
Once it is well planted, a healthy turf subjected to the necessary fertilizations (four interventions per year) and to the planned maintenance (regular mowing and autumn aeration) can be irrigated every other day or even less frequently. In any case, however, it will be necessary to allways provide a large quantity of water.
In the absence of irrigation it will be possible to use mixtures for rustic lawn characterized by the presence of different species, even dicotyledonous, with a more natural appearance and therefore perhaps less appreciable especially when observed closely, or even resort to walkable flowering meadows with a fairly high cost of planting.
Types of irrigation systems
Therefore, having an irrigation system for the garden allows greater freedom of choice regarding the plant species to be used and greatly relieves the burden of post-plant management.
However, it is necessary to distinguish irrigation of trees and shrubs from that for turf.
In the case of plants, the necessary water will be distributed by means of a drip irrigation system, in order to maximize the effectiveness of wetting thanks to the slow penetration of each drop of water into the soil until it is evenly soaked.
It is a matter of using sections of pipes equipped with valves spaced at regular intervals, called dripping wings, which allow a uniform leakage of water along the entire length of the pipe.
Immediately after planting the plants it will be necessary to irrigate daily or at most every other day, but after the engraftment period longer but less frequent irrigation times will be used.
In fact, more intense wetting, which affects a good part of the soil at greater depth, will have the effect of pushing the root system to deepen, making the plants more resistant and autonomous over time.
This is particularly true for trees, which should be watered even more rarely but providing considerable amounts of water at each watering.
In the case of turf, a sprinkling irrigation system is used in which retractable sprinklers come out of the ground to distribute the water as it was rain.
Alternatively, you can use a sub-irrigation system, or a network of underground pipes that give water directly to the roots, in a similar way to what happens with underfloor heating systems.
In both cases it is absolutely essential that the network distributes the water evenly over the entire affected surface.
It should be noted that, in the case of turf, watering is not the same as pouring water.
Irrigating means providing a uniform and constant amount of water over the entire surface of the lawn. In fact, uneven irrigation involves dry areas alternating with areas that are too wet, with harmful effects in both cases.
Distributing the same amount of water to the entire turf implies the preparation of a project of the irrigation system, in which it will be necessary to select the correct sizing of the pipes, the position of the various sprinklers, the nozzles to be used and the irrigation times to be programmed.
This implies the involvement of companies specialized in the design and installation of systems of this nature.
Pump, tank and control unit
The irrigation system will have to include some fundamental elements.
First of all it is essential to have a source of water available, which in gardens of considerable size must consist of a well, to avoid resorting to a precious asset such as drinking water.
The water taken from the well will be accumulated during the day in a storage tank, usually buried.
In fact, the water regime of the well will hardly allow us to have all the water necessary for the garden at the time of need.
The water will be taken from the well gradually over the course of 24 hours by means of a primary submersible pump, based on the water regime of the aquifer from which it is drawn. That is, a certain amount of water will be pumped into the storage tank until the well has emptied, after which the pump will stop and wait for its filling to draw more water and so on.
Watering the garden will take place once a day, in the early hours of the morning. As said earlier, It is important to avoid evening or night irrigation, which favors the onset of fungal diseases especially on the turf.
The various parts of the garden will be irrigated by dividing them into sectors, so as to be able to program the irrigation time and the amount of water needed for each area in a flexible way, based on the type of plants that we have planted in each sector and above all, the maximum flow rate that our pump can deliver.
Everything will take place in an automated way, through a control unit that is programmed according to the needs of the garden during the year.
The control unit will operate a collector equipped with solenoid valves, each connected to a sector of the garden: the opening of a specific solenoid valve will activate the secondary pump placed in the storage tank that will start the irrigation of that specific area.
It is useful to underline that with the irrigation system, it is possible to provide nourishment to the plant elements of the garden in an automated way.
In fact, fertigation systems in which certain nutrients are taken at predefined dosages and distributed directly mixed with irrigation water are increasingly spreading. It is a solution that, combined with the normal cycles of fertilization of plants and lawn, can contribute to substantially improve their state of health.
It is therefore a good idea to always provide an irrigation system when creating a new garden.
It is a system that must be designed and installed by professionals and is a significant part of the expenditure when calculating the cost of the garden.
However, it is a necessary element if you want to guarantee the maximum result from the investment made on plants and turf.
