Irrigation System Maintenance Through the Season

The irrigation system is the only installation in the garden that works while you are away, and whose work is judged only once something goes wrong. Until then everything looks tidy: the controller fires the zones, the heads pop up, the grass is green. Problems rarely announce themselves with a breakdown; more often it is a yellow patch along the edge of the terrace in July, by which time it is too late to put things right by watering.

This piece deals with what comes after installation, that is, with monitoring and adjusting a system that is already running.

Checking coverage: walk through a cycle

The most useful check is also the simplest. Once a month, run each zone manually, in daylight, and stand beside it while it works. Fifteen minutes or so for the whole garden, and it reveals almost everything.

There are several things to look at. Whether every head rises fully and retracts once it shuts off. Whether it has sunk into the turf or tilted out of vertical, because a tilted head throws its jet at an angle. Whether the rotary sprinkler travels the full arc set for it or stops short, which usually means its mechanism is full of fine sand. Whether the jet strikes a fence, a post or an overgrown shrub that was not there last year. And whether the jets from neighbouring heads really do overlap as far as the next head, because that is how the system is designed. Overlap that looks like too much water is the only way to get even distribution.

Signs the grass gives before you notice a fault

Grass dries out in a pattern that gives away the cause. A regular circle around a single point means a head delivering less than it should. A wedge spreading outwards from a head means a stalled or shifted arc. A strip along an edge means the head has sunk, so the jet cuts through the grass instead of flying over it. Scattered pale patches across a whole zone are usually not a fault but watering that is too short.

The container test: how much water actually falls

Minutes on the controller mean nothing until you know how many millimetres of water they deliver. That is easy to measure. Set out six to eight identical straight-sided containers across the zone, empty tins for example, some near the heads and some midway between them. Run the zone for fifteen minutes, then measure the water in each one with a ruler.

You get two figures. First, the average amount, from which you work out how many minutes a dose needs. A lawn in our conditions wants around 25 mm of water per week in total, rain included, and that spread over two deeper waterings rather than a daily sprinkle across the surface. That means a little over 12 mm per watering, so if you have collected 6 mm in fifteen minutes, the zone needs about half an hour.

Second, and more important, you get the difference between the containers. If the fullest holds twice as much as the emptiest, the zone is not balanced, and a longer run time will not solve that; it will only drench one part while the other is still thirsty.

The controller follows the weather, not the calendar

A schedule set in May is wrong by August and wasteful by September. Follow the season in a few steps: short and less often in spring, a full dose in July and August, then tapering off through September. After a rainy week the cycle is skipped, because rain counts towards those 25 mm.

Water early in the morning, between five and eight. In the evening the blade stays wet overnight, and that is an invitation to fungal disease. When the wind blows, the jet is carried away and the sheltered side stays dry, so on those days water in the earliest hours and split the cycle into two shorter ones. This is felt most at the start and the end of the season, when the košava, a south-easterly to east-south-easterly wind, can hang about for days in Srem.

Pressure drop and what it tells you

If the jet suddenly has no reach, or the heads barely rise, the pressure has dropped. Weak pressure across all zones points to the supply, the filter or the valve on the main line. Weak pressure on one zone alone points to that zone: a clogged filter in the head, a damaged valve, or a leak underground, betrayed by a permanently damp or unusually lush patch of grass.

Pressure that is too high is recognised by a fine mist instead of droplets. That water goes off into the air and away with the wind, and it is the commonest silent loss in a system.

Filters and nozzles

Water from a well or from a canal carries silt and fine sand, so the mesh filter on the main line is rinsed out several times over the season. The heads have their own screens beneath the nozzle: unscrew the head, take the screen out and rinse it under running water. Never with a pin or a piece of wire, because that permanently widens the nozzle opening and that head will deliver more than its neighbours for ever after. Drip systems need the same, only more strictly, since with them a blockage is not visible from the outside but shows only in a plant that wilts.

Why zones lose their balance over time

A system that was perfectly set on day one is no longer so after two seasons, and that is normal. The soil around the heads settles, the nozzles wear unevenly, and the garden itself changes: a once-sunny bed is today part shade beneath a canopy and needs less water than the zone beside it. So adjustment is not a one-off job but an item that recurs every season.

When to leave it to someone else

Rinsing a filter and levelling a head are things most people do themselves. Balancing zones, replacing nozzles and tracing underground leaks call for experience and tools, so those checks form part of seasonal maintenance contracts, along with mowing, feeding and pruning. If, even after checking, you cannot narrow the problems down to a single cause, through our work on irrigation systems we make a site visit, look over the installation and tell you what is really wrong with it, with no obligation to give us the job.

And one more thing at the end of the season: the first frosts in Vojvodina arrive in the second half of October, so the system should be drained before then. Water left in the pipes and valves over winter causes damage that only comes to light in April.