Weed control

Driveways and waste areas

The best weed-killer in this situation is a glyphosate product such as Roundup or Zero.

These products kill the widest range of weeds and grasses. Mallows and clovers are the only common weeds somewhat resistant.

Glyphosate products rapidly bio-degrade on contact with the soil.

They are of very low hazard to people and the environment.

Vegetable garden

Regular cultivation between rows and hand weeding are still the safest and most effective control measures for vegetables.

Mulching with straw or similar is also very effective at suppressing weed germination.

It is also important not to let weeds seed as this will make the weed problem worse next year. 

Flower garden

For annual bedding plant areas the same comments apply as above for vegetables.

Shrub and perennial garden

Here the best result is achieved by using a combination of strong growing ground cover plants or shrubs and mulching each year with straw or a garden mulch.

For a more permanent mulch and less work, weed mat can be used. This is a woven plastic sheet which when laid on the soil surface will stop weeds germinating, but allows rain to enter and the soil to breathe.

A decorative mulch such as granulated bark can be placed on top of the weed mat.

Mulching has an additional benefit of keeping moisture in.

Zero or Roundup can be used to spot spray difficult weeds that persist, but care must be taken to ensure no spray contacts leaves of desirable plants.

In the garden weeds compete with plants for light, moisture and nutrients. They can totally smother and kill small less vigorous plants. 

This page outlines control measures for different situations.

Weeds are simply a plant in the wrong place, they are a part of nature and have adapted to thrive in a particular position.

In the garden we can aid weed control by selecting plants which thrive and compete with weeds, rather than plants which are weak and unsuited to the area.

From the home gardeners point of view weeds fall into two broad categories.

Annual weeds- which are mainly a problem in cultivated vegetable and flower gardens.

Persistent perennial weeds -which tend to compete strongly everywhere.

In addressing weed control, it is important to consider in what situation is the weed growing.

Lawns

A well- drained, well fed lawn, that is mown high rather than short, will suppress weeds quite effectively, minimising the need to spray.

Weeds in lawns can be suppressed by topdressing 3 or 4 times a year with Tui Lawn Food. In addition it is recommended that lawns are mown at a high level rather than short. This allows the grass to grow thicker and suppress weeds.

Weeds in new lawns largely disappear after 5 or 6 mowings.

Once the lawn has been established for a year, most weeds and clover can be controlled with Grosafe Lawn Guard, to give wider control. 
Grosafe Lawn Guard is best applied in early spring (Mid – late Sept), especially for control of Onehunga / Prickle weed.

If Prickle weed is a serious problem, use Grosafe Prickle Weed Killer

If Hydrocotyle weed is a problem use Grosafe Hydrocotyle Weed Killer

If moss is a problem, consider whether the lawn is too shady, poorly drained, receives insufficient fertiliser, or is mown too short. It is important to correct these deficiencies first, or moss will continue to be a problem.

Yates Surrender Moss Killer can be used to control moss.