Irrigation Systems North Shore

North Shore irrigation for sloping sections and clay banks

Many North Shore gardens are on slopes. The land falls toward the Waitematā Harbour and the Hauraki Gulf bays, and sections around the East Coast Bays, Glenfield and Northcote often step down in terraces or banks. Water on a slope runs downhill, so a standard drip line delivers more at the bottom of a run than at the top. We use pressure-compensating drippers that give the same output along the whole line, and split upper and lower terraces into separate zones. Lawns on the flatter tops of sections can still use pop-up sprinklers, laid out so the spray patterns overlap evenly.

Inland the soil is clay over uplifted Waitemata sandstone, the same ground that made farming the inner Shore hard. Clay takes water slowly and banks shed it quickly, so the best approach is short, repeated cycles with time to soak in between, rather than one long run that washes soil and mulch downhill. On steep banks that is also about stability. Saturating a clay bank is never a good idea, and irrigation should put down only what the plants need.

The south-east of the Shore is different. Around Lake Pupuke and Devonport the ground is volcanic and was historically more fertile, and soils there tend to drain more freely. Gardens on that ground can take water a little more often without staying wet.

Coastal gardens along Takapuna Beach and the bays face wind, so spray heads should throw larger droplets or be replaced with drip where wind drift is a problem.

On the backflow side, Shore systems drawing from the mains carry a double-check valve on the garden branch, which then needs testing every twelve months, and we can set up that test as part of the job. A tank supply with mains changeover is another option for keeping terraced gardens alive through summer restrictions.

Local tip: On a sloping Shore section, run irrigation in short cycles so clay banks absorb the water instead of shedding it downhill.