Benefits of vetiver

A Kerikeri woman believes a non-invasive Southern Indian plant - vetiver grass - could be nature's secret weapon against environmental and climatic damage.
For the last eight years Wendy Hamilton-Gates has vigorously promoted the use of vetiver grass after she chanced upon its benefits following a visit by World Bank senior agriculturist and conservationist John Greenfield.
Considered a world authority on soil and moisture conservation, Mr Greenfield has spent 40 years worldwide developing a system of soil and moisture conservation that would be sustainable in extremes of climate.
He introduced the Vetiver System concept to India in 1980s and is author of the Green Book, Vetiver Grass - A Hedge Against Erosion.
At the time Ms Hamilton-Gates was the co-owner of a busy herb and lavender nursery - she put the plant in a bucket of water and promptly forgot about.
Months later she remembered the plant and was surprised to find it was still alive and thriving with a massive root system.
She planted the grass and after watching its rapid growth, she began researching how and what the plant was used for and became convinced of its benefits.
Apart from preventing slips and erosion she learned vetiver had been effective overseas in the cleaning up of toxic water from old sawmill sites where arsenic and other toxic chemicals were hidden in the soil.
It was used at old mining sites for stabilisation and chemical removal.
She says vetiver - a semitropical plant - grows well in the north. It is drought tolerant but can handle the odd drowning by flood water. It does not flower, seed or sucker, making it non-invasive and able to live for up to 100 years. Planted so it forms a hedge it can grow up to a metre tall and 60cm wide, (sometimes as quickly is within six months), but its root system grows straight down into the soil as much as four to five metres within a three year growing season.
The top can can be trimmed if desired or cut and fed to stock.
"Its dense hedge top takes the power out of the torrents of water during extreme heavy rain, allowing the water to trickle through the hedge, hence keeping the soil intact. Underneath the soil, the fibrous root system joins together - like holding hands and prevents the earth from collapsing," she said.
Nowadays Ms Hamilton- Gates' business has grown from a solitary plant to a thriving nursery that supports two contract growers.
When time permits she is happy to travel to sites that require her expertise and will work with property owners to ensure the vetiver is planted to achieve the best results.
She will also deal with water run off, land contour , soils and other related issues. Vetiver can be used to clean polluted waterways, in wetlands around rivers and lakes and in soils ranging from clays to sandy shale.
Ms Hamilton-Gates says her journey with vetiver has changed the way she plants and mulches her own garden.
"I have planted vetiver around the veggie gardens and orchard to keep away dogs and pesky pukeko which eat my fresh plump corn before I have a chance to harvest it, she said.
"I also use vetiver to mulch the garden - last summer's drought did not affect the growth of my garden because the heavy mulch retained the moisture around the summer crops."
October to April is the best time to plant vetiver - the longer days and warmer soils allow the plant to thrive - with or without water.
She recommended the plants were saturated with water when planted and then left to their own devices.
The plant has a natural purple tinge in winter but can be kept green by side dressings of blood and bone if desired.
Vetiver has other uses - overseas the leaves are woven into a number of craft and household items and it also used in the perfume industry.
Roots scattered into an old sack in dog kennels are reported to keep fleas away.