The micro-sprinkler for your garden

The Micro Sprinkler is a watering system particularly adapted to large flower beds and rock gardens.

The Micro Aspersion produces a very fine rain that waters at low pressure (it does not damage the flowers, even fragile ones) and over different distances quite wide (1 to 3 meters radius depending on the brand).

This one is very easy to install since all the pipes are on the surface, with connectors to be plugged or screwed: many parts are common with a Drip system (see sheet: balconies and terraces). However, never mix micro-sprinklers with drippers on the same pipe.

So, a programmer on the faucet, a piece of garden hose with fittings, a filter + pressure reducer, PE hose with a diameter of 13x16, ground spikes to hold the hose in place, a small shut-off valve at the end of the hose that will allow for easy draining in the winter (since the hose is on the surface, it is not protected from the cold)

Once the main 13x16 pipe is in place, simply create branches on small pipe (4mm or 4.6mm) to a support.

At the top of this support, the micro-sprinkler is screwed or plugged in.

Note that the small tube branches should be relatively short (generally not more than 1 meter) and that between the support and the micro-sprinkler, it is often possible to place an extension (to raise the micro-sprinkler according to the vegetation) and a small regulating tap (to adjust the distance of the jet).

A micro-sprinkler is placed every 2 or 3 meters or so (depending on the technical characteristics): the jets must cross each other, as one sprinkler must always try to water its neighbor.

Even if they water at a pressure of a few bars in fine rain, the micro-sprinklers can have a large flow (up to 100 liters for some). It is therefore not possible to place too many of them on a single pipe.

The main technical advantages of micro-sprinklers are, if compared to drip irrigation:

• Excellent watering coverage over a large area (for a rock garden for example). The drip only waters a strip of land about 60cm wide.
• less hoses to pass through the beds, it facilitates the maintenance/planting and reduces the risks of breakage.
• in a caricatural way, where 50 drippers are needed to water a bed, we obtain a much better water distribution with only 5 sprinklers.
• the sprinklers, in height, do not get blocked, contrary to drippers which can end up being buried in the very dense massifs.
• it is easy to move a sprinkler since it is always in branch of the main pipe on a support planted in the ground. As a remark, I would indicate that the solution of putting the sprinklers directly in the 13x16 pipe is not qualitative in terms of watering and can, in some cases, be defective very quickly (from the second year).
• finally, the micro-sprinkler system is aesthetic when it works (editor's note: you will tell me that it must work around 2:00 am, and that the visual aspect is not essential at this hour ....)

All this being very easy to install, I wish you a "good installation".

Micro-irrigation to save water

Micro-irrigation is an effective water-saving technique that offers a solution of choice for both gardeners and agricultural companies. With an incomparable efficiency, this system allows to water the plants at the right time and at the right dose.

What is micro-irrigation?

Developed in the early sixties, micro-irrigation ensures optimal distribution of water under low pressure directly to the feet of the plants concerned. Of course, already in ancient times, the issue had been addressed by the use of oyas, these porous buried jars that ensured effective watering close to the roots.

But let's go back to the current system which has the advantage of being able to be planned by cycles, according to the climatic conditions, and which allows to choose the flow intended for each plant.

Otherwise known as 'localized irrigation', this technology was created in Israel in 1959, when the advent of plastic pipes allowed its development. Patented in 1960, drip irrigation quickly took off in America and Australia. Nowadays, this system is recommended in arid countries and in hot climates. Unlike conventional irrigation, which waters the entire soil indiscriminately using maximum pressure, micro-irrigation provides water in a punctual manner, on a well-defined area of the soil and at low pressure.

What does a micro-irrigation system look like?

There are several micro-irrigation media, although drip irrigation is the best known and most widely used, especially by individuals.

• The drippers work under a pressure of 1 bar. Each dripper is fixed independently on the whole length of a pipe of 0,5 to 1,5 mm of diameter. With one or more holes for water flow, the dripper can be chosen or adjusted (depending on the model) to the right flow rate for each plant (from 0 to 20 l/h).
• Micro-sprinklers, micro-diffusers or micro-sprayers are generally used in arboriculture. They can be fixed on a stake and diffuse water on 40 cm by rotation of the cap with an adjustable flow from 0 to 60 l/h.
• Micro-porous pipes are perforated with a multitude of small holes from which the water flows at low pressure along the whole length.

Advantages of micro-irrigation

This controlled watering technique allows enormous water savings (25 to 40%) compared to flood or runoff irrigation techniques with an efficiency 40% higher.

• Micro-irrigation can be coupled with a programmer, or even a weather station or an application to manage the watering according to the real needs corresponding to the climatic conditions. You can even be notified in case of water shortage or technical problem.
• Evaporation is less, especially when the system is activated at the end of the day. It also helps avoid many cryptogamic diseases that spread through the watering of foliage.
• The hydric shocks so harmful to plants are avoided. Plants not stressed by the lack of water are more vigorous and less sensitive to parasites.
• In a large farm, it allows to reduce labor costs.
• The rooting of the plants is favored by this system.
• There are far fewer weeds, which avoids competition for cultivated plants and tedious and time-consuming weeding.
• This technique allows for the direct addition of fertilizer during watering in large-scale agricultural operations.
• Knowing that the water consumption of intensive agriculture corresponds to nearly 70% of the world consumption, that water resources are beginning to decline or even disappear in some areas, the problem of food security may become burdensome. Micro-irrigation helps to overcome this problem.

Disadvantages of micro-irrigation

Although few in number, there are some disadvantages to installing a micro-irrigation system.

• The cost can be prohibitive when it comes to irrigating a large plot of land. However, at the level of a medium-sized private garden (500 m²) or even better, a simple balcony or terrace, it is possible to obtain very affordable kits that will quickly pay for themselves.
• Another concern is the technical nature of the installation (calculation of pressure losses, installation of the pressure reducer, knowledge of the right pipe diameters, creation of the different circuits, adjustment of the flow rate of the drippers and their number, installation and adjustment of a possible programmer...) which can frighten the novice gardener or those who are not very handy.
• The drip system should be checked often enough because some drippers can be clogged, especially by ants or soil debris.
• Leaks and breaks are not impossible, especially after the brushcutter has been used! If you don't do your own brush cutting or mowing, always remember to tell the person in charge of this work that an automatic watering system is in place, otherwise your garden will be compared to the water games in Versailles as soon as the watering system is turned on!

The installation seen from the trenches

You have now the technical study in hand to realize your underground watering system. Now it's time to tackle one of the most difficult parts (for the arms...): the earthwork.

Let's see the steps and our advice for the earthwork for the installation of your underground sprinkler.

1/ The trenches

Make the trenches as shown on the plan

The width does not matter. A trencher makes cuts 9 cm wide and this is more than enough to pass pipes and sprinklers. If you are working with a backhoe, there are small buckets that make narrow trenches (so there is less soil to put back in place afterwards!). Finally, with a spade, there is no choice but to get the width of the tool.

Remove all the stones if possible.

In terms of depth, there are several opinions...

• I often advise 35 cm minimum (a little more than a spade).
• It is useless to dig at 60cm to protect yourself from frost. In some regions, if the winter is very hard, the ground can freeze very deeply. It is better to foresee anti-freeze systems as soon as the installation is done.
• The idea of putting the pipes at 90 cm to be sure that nothing freezes is very risky: the sprinklers are on the surface, and they will be damaged by the cold: it is therefore better to have the possibility of draining the whole installation. Moreover, at this depth, when it is necessary to intervene to modify or repair, it is very complicated. Think about the hole that will have to be made for a simple connection to be added.

Don't forget when opening the trenches to foresee the location for the manholes (see manhole picture).

2/ Setting up the pipe network

Unroll the polyethylene pipe at the bottom. In case of important presence of stones or pebbles, put a bed of sand under the pipes (in this case, dig deeper).

Install fittings and sprinklers.

DO NOT PLUG UP!

At the end of the line, do not put the plugs in yet. You must first send water into the pipes to clean them of all the debris that could have slipped inside. (see photo turbine380)

Screw in the plugs once this step is completed. Shim and adjust your sprinklers. Leave the system running and check ALL the connections.

There are no leaks after your installation? You can now fill in the gaps...a little...

3/ Locate the water network

3) If you have a 40 cm deep trench, put 20 cm of earth and then put a blue wire mesh. This will avoid piercing the pipes if you have to work on them in a few years: it will indicate the presence of pipes underneath. The blue color of this plastic mesh is important, it is a recognized standard for water (for information, green = telephone, red = electricity, yellow = gas).

4/ End of the earthwork

That's it, you can fill it in completely. Let the soil settle for several days before renovating the damaged lawn.

Technically, the trenches are not the most difficult part, but a well done earthwork allows an easy maintenance during the following years.

Underground irrigation programmers

The use of a buried automatic watering controller allows you to control the watering time at the most convenient time of the day. 

One of the most important ways to save water is to water only as long as you need to, when evaporation is lowest, i.e. in the middle of the night or early morning.

To do this, your underground watering system must include an important element: the programmer. It will allow your installation to start and stop at the desired time; it will control the solenoid valves, so that your garden is watered in successive sequences: we speak then of several networks or ways.

There are four main types of multi-network programmers:

1. The battery-operated programmer, connected to the solenoid valves by a cable with many wires. This is a choice to be reserved exceptionally for places where there is no power supply. Compared to other options, this product is quite expensive. (main manufacturer: RAIN BIRD).
2. The wireless battery or current programmer. This one is connected by waves to the solenoid valves. The installation is thus strongly facilitated.
3. On the other hand, it is still a very expensive product, but practically all suppliers are trying to develop this type of programmer. We can therefore hope that the prices will decrease in the years to come. (Main manufacturers: RAIN BIRD, GARDENA...).
4. The wall-mounted programmer, with a separate transformer (photo opposite), connected to the solenoid valves with a multi-core cable. This is the best quality/price ratio. There are, apart from the "first prices", very reliable models at around 75 Euros that can control up to 6 solenoid valves. The only problem is that these products must be installed indoors (garage, cellar, storeroom, etc.), near a power outlet, as the electrical transformer (220v/24v) is not protected from water projections. (main manufacturers: RAIN BIRD, NELSON...).

The wall-mounted programmer, with an integrated transformer, connected to the solenoid valves with a multi-core cable. This is the largest choice available on the market. There are all models (from 2 to 48 networks) and all prices (from 170 Euros for the big brands). These devices have the particularity to be in the standards for a wall installation outside, even in the rain.
They are also products that can be installed inside. The advantage is that there are less visible wires, the transformer being included with the programmer in a single box, with a door that can be closed. (see photo below)

Logically, the many existing models and the discretion in terms of wall installation make these products very often preferred by craftsmen. (Main manufacturers: HUNTER, RAIN BIRD...).

The purchase of a programmer should not be based solely on its price: it is the submerged part of the iceberg (the rest of the installation being buried) and you will use it frequently (changing the watering times according to the season for example).

So you need a model that is easy to modify.

More and more products are available with hundreds of programming options. Even if you don't need all of them, the more options a controller has, the easier it is to adjust if you only focus on what you need for your garden.

So don't necessarily look for the cheapest one that seems simple, as this may limit the use you want to make of it.

Finally, in addition to the notions of saving water, a programmer is obviously a comfort of use, like all the rest of an underground watering installation.

Note that there are now programmers accessible from your smartphone.

Installation of a solenoid valve manhole for an underground irrigation system

Here is an illustrated example of a solenoid valve assembly in a manhole. This one, as well as those that could follow, is only an example among many solutions or preferences that each installer may have. Nevertheless, some basic principles are stated.

1/ Mounting the manifold

Here two solenoid valves with the water inlet in the center. Although there is a main water cut-off, a shut-off valve is always placed at the manhole inlet. The solenoid valves are removable before and after, by the "removable union" type fittings. The solenoid valves have been disassembled so as not to bother with the wires, protective tape (orange here) prevents the intrusion of earth. Pipe primers allow the manifold to be mounted completely without worrying about the rest of the piping.

2/ Positioning the collector

After the hole has been made for the manhole (wider than necessary), the bottom is laid flat, the solenoid valve manifold is placed, as well as a sheath here to allow the cable to be passed later. The pipes under the manifold allow to raise it a little with respect to the level of the manhole (the usefulness of this will be seen later).

3/ Arrival of the manhole

The manhole has been cut with a hole saw in order to let the pipes pass. It is positioned over the collector. We check that it is level and aligned with the limits of the garden (wall, alley, ...). Note that the manhole is deliberately larger than necessary: it is a false economy to try to put a maximum number of valves in a small manhole; maintenance and repairs are difficult, the connections are not accessible, ...

4/ Wedge the manhole

Once the manhole is correctly in place, we start to backfill all around it, gently so as not to shift it. The geotextile film is pulled up along the outside walls so that the soil does not enter the manhole.

5/ Backfilling

Once the manhole is in place, it can be completely filled in. The pipe primers are useful on some sites where the manholes are installed well before the garden pipes.

6/ Manhole bottom 

The bottom of the manhole is filled with pebbles. The pieces of pipe which supported the collector are removed.

7/ Cleaning

The manhole is cleaned with water. All the components of a collector are watertight, so it can be washed with water. The solenoids are screwed -by hand- on the solenoid valves, the wires will not interfere anymore. The multi-core cable coming from the programmer is brought into the manhole, longer than necessary (it will not be cut).

8/ Connections

All that remains is to connect the wires of the solenoids with the cable, using waterproof connections. Here, the connections are enclosed in a box, for cleanliness reasons, so as not to leave unsightly connections lying around: be careful, it is never the box that makes the watertightness, but the specific connections used.

Renovation of a solenoid valve manhole for underground watering

Here is an example of a manhole installation using existing cables or pipes.

1/ Assembly of the new manhole

After the old manhole with its solenoid valves has been completely dismantled (the cables are not cut, it is better to keep the connections), a new complete manifold is assembled, adapting to the existing one.

Here, three watering networks, drip, so three solenoid valves. A stop valve was added at the entrance of the collector, as well as a second valve to easily purge the collector before the winter.

This is a solution that I recommend very regularly (even if it is not systematic). Removable fittings before and after the solenoid valves.

2/ The manhole

We check and try the positioning of the manhole. In renovation, it is always a little more complex than in a new creation. It is necessary to check that a maximum of elements and connections are inside the manhole (and not under the edges, the walls, inaccessible).

3/ Connections

The manhole has been installed, wedged and filled, it is time to make the watertight connections.

Here you can see the old connections (brown), which have not been removed in order to identify the wires as the new connections are installed (blue or black).

4/ Finishing

Once finished, a bottom of garviers or pebbles, then we wash the manhole; the old grey cable has not been shortened, and there is room in this large manhole to work if needed.