Irrigation, not irritation – including tips for winter

As the season draws to a close, the winter months are the ideal time to review how your irrigation system has performed, says Peter Robinson, our Technical Area Sales Manager for the North-West of England. With over 30 years’ experience as a nurseryman and precision irrigation/fertigation specialist, he outlines key factors to assess when designing or reviewing a system, followed by practical tips for winterising it.

Well-designed and correctly operated irrigation systems are worth their weight in gold but often under-appreciated. When functioning well, they deliver major value through improved crop uniformity, reduced labour, more efficient nutrient use, and fewer disease problems. When they don’t, issues accumulate quietly until they become impossible to ignore.

Uniformity is key

A system should never be judged solely on whether it applies water. The real measures of performance are uniformity, application rate, and the hydraulic stability of the entire network. Poor distribution leads to uneven growth and rooting, while incorrect application rates can cause leaching, run-off, or inadequate wetting.

Pressure differences across zones are another common cause of inconsistency, particularly as systems age or production areas expand. Modern irrigation should also integrate reliably with fertigation, biostimulants, and biological inputs such as our Seeka nematodes. If a system cannot dose accurately, growers risk wasted inputs and reduced effectiveness.

Water source matters

System design must suit the nursery’s conditions, and the water source is a critical variable:

• Mains water is stable but expensive.
• Borehole water often requires filtration or pH correction.
• Rainwater is sustainable but needs pre-filtration and biological management.
• Recycled water demands robust filtration plus continuous monitoring of EC, pH, and potential pathogens.

The irrigation method – overhead sprinklers, drip lines, or booms – must match both crop type and production layout. Sprinkler uniformity depends on nozzle choice and pressure; drip systems need pressure-compensating emitters and balanced manifolds; booms can offer excellent control for container crops but rely on consistent pump output and high-quality filtration.

Systems drift over time

Hydraulic design is the backbone of any irrigation system. Pipe sizing, pump capacity, filtration rating, and valve configuration must all meet peak seasonal demand. Even the best-built system drifts over time, making pressure gauges and accessible flush points essential for diagnostics. A pressure variation of more than 10% within a zone is a warning that maintenance or redesign is needed.

Tips for winterising your system

Winter brings its own challenges. While some growers have pumps and pipework in frost-free environments, most are less fortunate.

Pumps, valves, and pipework are particularly susceptible to frost – especially in unheated structures. Protecting the pump house is the first priority: insulate the building and maintain a frost-free temperature with a thermostat-controlled heater or temporary heat source during cold spells. Trace-heating cables can help protect exposed pipework, but the system must still be thoroughly drained.

Pumps, manifolds, and pressure vessels should be emptied using drain plugs; compressed air can clear remaining water. Control valves and outdoor pipework require similar care. Solenoid valves are best removed and stored dry, though good insulation works when removal isn’t feasible. External pipe runs and spray lines should be drained and blown through.

Sprinklers and drippers need particular attention because many contain anti-drain features that trap water, making them more prone to frost damage. These should be drained or isolated.

When planning new systems or upgrades, include accessible drain points and break points – small design choices that make every winter far easier to manage.