Weed of the month: Wild Ginger

Why is kahili ginger so bad? Because wherever the kahili ginger (Hedychium gardnerianum) goes, nothing else grows and, most alarmingly, it doesn't mind shade and can grow within native bush.
Nothing can grow through the mats of tubers and the dense leaves block light and smother natives. It spreads easily - birds disperse seeds and fragments of tubers will produce new plants in forest, plantations, unfarmed land, streams and road edges.
It's everywhere and weedbusters around Northland have worked long hours digging up or spraying the plant.
Their hard work was illustrated this year when Peter Harding, of Whangarei Heads, was able to employ two men for two days a week as opposed to last year when five men worked 32 hours a week each.
The ginger has been reduced to one large area on the Taurikura Ridge, which they will tackle in the coming months, and they are keeping a watchful eye on previously treated sites.
Small infestations keep appearing, possibly because of birds. Of the 14 species of weeds they deal with, there is growing concern about the rapid spread of privet.

The Southern Hokianga Ginger Group have a team tasked to go on to public and private land to get rid of ginger in the south Hokianga around Waimamaku. Ginger was all along the roadsides when they first started work 12 years ago.

Weedbuster Raewyn Honeybone is keen to set up a group at Matapouri to deal to ginger and Herekino Landcare has a programme in place.
Despite its name, this tall vigorous perennial from India is not edible. Introduced into New Zealand in the 1890s, kahili ginger spread rapidly out of gardens; beginning in the Waitakere Ranges and spreading up to Northland, across the East Coast, and all the way down to the South Island's West Coast.
Don't be seduced by the striking yellow flowers and shiny red seed capsules. The root system has to be seen to be believed; tortuous tubers pile up on one another forming extensive root mats. This plant is an unwanted organism and is banned from sale, distribution and propagation.
When digging out kahili ginger, make sure all the roots and tubers are removed as they can go a long way down into the soil. This can be backbreaking work.
If you have large areas, you may need to consider using a herbicide; check out www.weedbusters.org.nz for more information.
Ginger tubers can't be composted so it's a case of bagging and binning for deep burial or a trip to the refuse transfer station.
A couple of nice natives you could try instead are parataniwha (Elatosterma rugosum) or the rengarenga lily (Arthopodium cirratum).