Weeds are some of the most persistent and determined plants in nature, they often survive in the most barren of soils.  Weeds compete for valuable nutrients, light and moisture and they can harbor a wide range of pest and diseases.

Weeds seeds arrive in your garden in various ways, by sticking to your shoes and clothes, carried in by birds and wind. Often just cultivating the soil can bring seeds that have laid dormant for years to the surface where they will germinate.

Keeping weeds under control is an ongoing job in the garden, there are many methods you can use and the most convenient is to use weed killers.  The choices of weed killers can be a bit daunting as there are so many different types on the market and depending on their chemical makeup they each have a different type of killing action. Understanding the killing action will enable you to choose the right product for the job.

Selective- this will only kill the weeds that it has been blended for – the type of weeds that it kills will be shown or stated on the bottle. These types of herbicides are commonly used on lawns where they will kill broadleaf weeds, clover, prickle weed and moss but not the grass.


Non-selective- these herbicides will damage everything the spray touches, even desirable plants in the garden, and so special care must be taken to prevent spray drift.


Knockdown weed killer does just what is say’s it will it will very quickly knockdown the green growth but still leave the roots intact and the weed can grow again.


Pre-emergent or residual weed killer acts as a barrier over the ground preventing weeds from growing through this barrier. It is better to remove the weeds so you are spraying on to clean area and once sprayed it will stay weed free for any where up to 9- 12 months depending on the amount of rain. Often used over large areas of paving or cobblestones, it can also be applied with a watering can for large areas.


The McGregor’s Weed Out range explained:

McGregor’s Weed Out –Non Selective.  This is the most used weed killer around the home, this chemical compound breaks down quickly and will not remain in the soil so the sprayed area is ready for replanting within a couple of days.  Controls – Couch, Paspalum, Kikuyu, Thistles etc.

McGregor’s Weed Out Lawn Weed Spray –Selective. A weed killer that can be used on your lawns; it is blended to control weeds in your lawn without harming the grass. Controls - Clover, Dandelion, Cat’s ear, Chamomile, Thistles, Chickweed, Dock etc.

McGregor’s Weed Out Woody and Scrub Weed Spray – Non Selective.  For the tougher woodier weeds and vines this spray can also be applied straight to the stumps of woodier weeds to prevent re growth.  Controls - Broom, Ink weed, Wild lupins. Buttercup, Cape ivy, Dock, Thistles, Convolvulus etc.

McGregor’s Weedout Amitrole – Non Selective. This is for the harder more difficult to kill weeds, so be careful around your favorite plants as it will damage what it touches. Controls - Bamboo, Couch, Kikuyu, Wild onion etc.

McGregor’s Weed Out Path and Patio Weed Spray - Non Selective. This weed killer is used to control weeds in areas where long term control is required, cobbled areas, driveways, paths and fence lines. For the best result spray the area with McGregor’s Weed Out first then once the growth is dead, clear away the dead foliage and apply to the bare surface and this will prevent germination of weeds for up to 12 months.

 McGregor’s Weed Out Onehunga Weed Spray – Selective. For Onehunga weed in your lawn, and will not kill the grass, for the best results use in October and again in autumn.  This is when the weed is in its most active phase and producing flowers.



  • Oxalis can be a very tenacious weed to get rid of as not all the bulbs will sprout at the same time, successive spraying will be needed.
  • Onion weed is also a bulb and can take a few applications to remove all the plants, as the bulbs will often sprout at different times.
  • The active ingredients in all weed killers will over time lose their efficacy, so if you are using up old bottles – you may not get the best results. The best way to remember the date of purchase is to write it on the bottle in felt pen.
  • Mowing over dock and dandelion will not remove them as they continue to re grow from a long tap root you will need to spray or dig out the plant by the root.
  • For around the vegetable garden use McGregor’s Torpedo Hoe regularly, this will lift the smaller weeds out by the roots.