Cultural Backgroung

The onion (Allium cepa L.) is a biennial herbaceous plant belonging to the Liliaceae botanical family. However, commercially an annual cycle is carried out, with sowing (or transplanting) with times varying according to the destination of the product and the photo-periodic requirements of the cultivars used. Whether it takes place in late summerearly autumn or late winter-early spring, the biological cycle of the plant does not exceed four-five months.

Physiological characters and irrigation management

Although it adapts to drought (cylindrical and wax-covered leaves), irrigation plays a fundamental role in onion cultivation, allowing for high production standards, increasing the yield per hectare, standardising the size and calibre of the bulbs and improving their aromatic characteristics.

The water requirement of onions is about 2000-3500 m3/hectare/year, which varies according to the growing area and the season’s climatic conditions.

Generally, there would be one-two weekly irrigations at the beginning of the cycle, up to three times/week or daily during bulb enlargement. This is the phase that is most sensitive to water stress and responsible for reducing the calibre of the bulbs.

Irrigation schedules lengthen as the harvest approaches, with irrigation being suspended about 10 to 15 days in advance to encourage complete leaf senescence, allow the bulb to ‘settle’ well into the soil and ensure optimum shelf life in the post-harvest period.

Irrigation system for onions

Although spray irrigation is widely used, drip irrigation has also been common practice for onions for some time. Thanks to the localised water delivery, this system ensures an irrigation efficiency of around 90% and a drastic reduction in fungicide treatments as the aerial part of the plant is not watered.

Given the short cultivation cycle, Irritec offers its lightweight continuous-labyrinth driplines (Tape and eXXtreme Tape) for seasonal use or the lightweight drip line with flat dripper P1 (also available in two versions P0 and P5, respectively with an ultra-compact drip line and a longer, more robust drip line) which is also suitable for multi-seasonal use.

The recommended hourly flow rates are 0.9 or 1.2 litres, while both the spacing between the drippers (generally 10-15-20-30 cm) and, even more, the distance between the wings depend on the type of planting (single rows, twin rows, groups of three-four-five rows, high or very high seeding density, etc.).

For small-scale systems where a large part of the cultivation work is manual, you can opt for classic drip heads with flat (D5, M5, D7) or cylindrical (Junior and Tandem) drippers, ensuring a product life of several years.

For the main and header hoses and the classic polyethylene pipes, Irritec recommends the LayFlat pipe, which, being light, flexible and easily rewindable at the end of the season, is well suited to cultivating onions, which are usually rotated in different plots.


The onion benefits from a pH close to neutrality and electrical conductivity of no more than 1.2 mS/cm: higher salinity values can lead to a drop in production or even compromise production altogether.

This is why, in addition to a simple injection of fertilisers into the piping, it is essential to monitor the two main parameters of the irrigation water (pH and EC).

Irritec offers solutions that are simple to install, easy to use, and suitable for short growing cycles such as onion cultivation: the automatic Dosabox junior, for example, is a simple, modular fertigation machine that is suitable for both greenhouse and open field use. Its operation is based on injecting up to three fertilisers (+ corrective acid) via a set of injection pumps using the Venturi tube system.

It is supplied ready for connection to any existing irrigation line. It is equipped with an EC/pH/Temp. display and has two different selectable operating modes: proportional dosage – dosing fertiliser in a percentage proportional to the water flow rate (requires a volumetric meter with pulse emitter on the main pipe) or volumetric dosing – dosing one volume of fertiliser per hour.

Onion cultivation - Drip irrigation system - Irritec

A practical example of how to drip irrigate onions

Onion irrigation system -Irritec

Here are the Irritec products you need to drip irrigate onion


P1® – Irritec Tape®

High-quality hoses with turbulent flow dripper designed for open-field irrigation Easy to lay and install, they have excellent occlusion resistance. Available in various models, covering long lengths with maximum uniformity of delivery.

P1 and tape for onion - Driplines Irritec



Single-ply PVC flexible pipeline reinforced with a high-strength fabric that is easy to handle and store. Facilitates end-of-season operations for irrigation systems that need to be moved quickly and safely. Lightweight and flexible yet durable, it reduces installation costs and recovery time. Easy to cut and equipped with a wide range of connections makes the layflat pipe system an indispensable accessory for drip irrigation of tomatoes. Available from 2.4 to 6 bar, in all commercial diameters from 1 1/2″ to 8″.

Pipes for onion irrigation - Irritec



Irritec® filters provide the best filter protection for every irrigation system. The simple and safe structure, the result of precise construction technology, reduces maintenance to a minimum. Resistant to pressure fluctuations and external stress, the filters feature robust and flexible filter elements. Hydraulic tightness is ensured even at high pressures and the filter elements guarantee maximum filtration efficiency. The variety of filtration degrees available (from 20 to 450 mesh) can meet all filtering needs.

Filters for onion irrigation - Irritec



Irritec® injection systems are reliable and easy to use. They allow the injection of fertilisers (liquid or diluted in water) at rates of between 150 l/h and 1700 l/h (depending on the model).

Fertigation system for onion irrigation - Irritec



Complete range for connecting tape, light and classic dripline, available in sizes 16, 20, 22, 23, 25 and 29 mm.

DRIPLINE FITTINGS AND BRANCHES for onion irrigation - Irritec

Discover how to irrigate others crops

Irritec wants to make life easier for those who take care of the plants, for work and for passion. We aim to ensure that every drop is spent as well as possible, minimizing the ecological footprint.

Agronomic Irritec Team support the farmer also on after-sale and installation, with continuous assistance and efficiency control. Continuous attention to the customer needs to provide succesful and sustainable solution with an efficience service.