Our District

Deep pipes: a case study, Waikanae MenzShed

Remember summer 2017, when it barely rained from October until January? Despite the drought, trees and shrubs planted at the Waikanae Beach MenzShed thrived – thanks to being planted with deep watering pipes.

“The idea is that the roots get deep down,” says gardener Jim Fraser. “If the water gets down, the roots will stay down there. Then even if the top layers of soil dry out, the roots can still get water.”

Watering pipes went in, for example, with a row of feijoas donated by Gus Evans at the beginning of summer. Each tree has its own 60cm length of black flexible drainage pipe. “You can use any pipe,” says Fraser. “Offcuts of downpipe, drainage pipe – you don’t need to spend a lot of money.”

MenzShed gardeners Jim Fraser, Ron Blackmore and Peter Moldenhauer

The pipes were filled by watering can or hose every few days at first, down to once or twice a week once trees are established. Every now and then, a handful of sheep pellets also goes down the tube for fertiliser. “At home I have a pipe next to the lemon tree, and I put in the fish guts and fish heads, chop them up and put them down the pipe,” says Fraser. “You have to put a brick on top though or the cats will try to get them.”

A good thick 10cm layer of mulch around the shrubs also keeps soil from drying out, protects roots and keeps away weeds. (An added advantage of the watering pipes is that you’re not watering weeds, which tend to be surface-rooting.)

Being only a block from the beach, the MenzShed are on a base of pure sand - yet a few simple waterwise tricks have helped their garden thrive, providing vegetables and fruit for members and surplus for Waikanae Foodbank.

Any pipe offcuts can be used

  • Ideally, deep pipes go in at the time of planting a tree or shrub, so there’s no damage to the roots (if they can go in later, it can be fiddly to dig the hole.)
  • Angle or curl the pipe if possible so it finishes directly below the trunk, in the centre of the planting hole, so you don’t end up with a lopsided root system. Alternatively, put one pipe on either side of the tree.
  • Plastic bottles can be buried upside-down next to a plant, with a flap in the bottom for refilling, if pipe isn’t available. For a plastic-free option, lengths of thick bamboo also work.
  • There’s no water runoff, even on slopes, and plants have been proven to form much larger root systems. (See Gardening with Less Water, David A Bainbridge, available in Kāpiti libraries.)



Akeake are thriving in the sand, despite the drought

Other waterwise techniques used by the MenzShed gardeners include growing green manures, shown here after being dug into a bed

Find out more about deep pipe irrigation here

Last updated 14 June 2018 12.23pm