Pittosporums, trimmed every four to five years, can be used
in shelter plantings under irrigation, native plant
specialist Hugh Thompson says. Photo from Allied Press
Native plants can help farmers in a multitude of ways,
South Canterbury expert Hugh Thompson says.
Speaking at the Trees on Farms workshop at Pleasant Point on
April 30, Mr Thompson said native species could be used in
shelter belts and riparian plantings, for soil stability in
creeks and steep areas, for biodiversity, and for aesthetic
''They look natural and they're there forever.''
Six years ago, concerned by the neglect of native vegetation
on farmland, Mr Thompson became a full-time horticulturist
and started a native nursery.
''All the work is in the first few years, then they manage
and perpetuate themselves,'' he said of native plants.
''They do well in Canterbury under irrigation. Centre pivots
provide a great opportunity.''
Flaxes, coprosmas and pittosporums could be planted to
provide shelter without interfering with irrigation.
Pittosporums would probably need to be trimmed every four to
In shelter belts, natives were almost as quick to establish
as introduced species, especially in South Canterbury, Mr
''They do well in wetter areas. They don't fall over.''
Before planting, it was important to get the fencing right,
he said. He saw ''a lot of poor decisions about where
fencelines go'', sometimes leading to runoff straight into a
Fences should allow room for vegetation buffer zones.
''Some fencing just hugs the creek. There's no room for trees
Trees that shaded the water could help improve stream health.
Preparation of the planting site was also important, Mr
Thompson said. He advised spraying early to clear unwanted
vegetation that could hinder native species' growth.
Rank grass, twitch and heavy weeds often needed a double
spray before planting. He mostly used glyphosate, which was
most effective on twitch.
''Sometimes it takes me almost a year to get rid of twitch.''
Farmers should order their plants early.
''There can be a big run on certain plants some years.''
Mr Thompson said he tended to get the biggest plants he
could, so they were easily visible when spraying and would
grow more readily and evenly.
''I operate on a 90% to 95% success rate. I can't afford
failures. My aim in the first year is to have them weed-free.
That might involve three sprays. I can basically leave them
When planting, there should be no potting mix showing above
the ground, he said.
He usually spaced the plants 1.5m to 2m apart. The closer
they were, the more readily they smothered grass, but that
could be a lot more expensive than wider spacing.
''Sometimes groups of plantings are better than big blocks.
With natives, they look natural.''
Bigger species such as miro, totara and kahikatea could work
well among plantings, Mr Thompson said.
- by Sally Brooker