How to Control Pigweed in Your Lawn

Pigweed is a low-growing, succulent plant with reddish stems and small, fleshy, oval-shaped leaves. It produces small yellow flowers that develop into seed pods, allowing it to spread rapidly. This weed thrives in warm conditions and is commonly found in lawns with thin or weak turf coverage.

Pigweed is particularly prevalent in coastal and inland regions of Australia, flourishing in disturbed soils and areas with high sun exposure. It can invade all major warm season grass types, including Buffalo, Couch, Bermuda, Kikuyu, and Zoysia. Cool season grasses are less susceptible as the weed prefers warmer temperatures.

Pigweed will germinate in lawns with thinning canopy coverage, so ensuring a lush, healthy lawn is a great way to stave off invaders like Pigweed. Pigweed spreads through the seed pods that develop out of its distinctive yellow flowers, and like most weeds it’s a voracious grower, meaning once those seeds are distributed the weed can take hold quickly.

Pigweed also spreads through its underground root system and can shoot from stem fragments, meaning outbreaks should be cut a wide berth with the lawn mower and line trimmer until the outbreak is controlled.

The weed is most active during the warmer months of Spring and Summer, as it thrives in high temperatures and can tolerate drought conditions.

Manual Removal

Pigweed outbreaks can be managed by manually removing the plant, ensuring to remove the entire root system without distributing any seeds. You may find this easier to do when the soil is damp and soft, such as after rainfall or irrigation, and a small forked hand weeding tool might make the task easier.

Using Herbicides

Chemical control is the most effective way to manage weeds like Pigweed. Currently, few herbicides are registered as being effective for Pigweed specifically, but many common active ingredients like Dicamba and MCPA have shown efficacy in its knockdown.

LawnPride recommends Contra M Duo for the treatment of Pigweed, though this product is not safe for Buffalo lawns.

The efficacy of liquid herbicides can be improved by using a surfactant like Wetter 600 to help the herbicide stick to the weeds, improving first round kill rate. It’s also recommended that you abide by the manufacturers recommendation when it comes to application rates, and ensure you’re spraying safely using their recommended protective equipment.

Luckily, invasive weeds like Pigweed/Purslane can be managed through the use of a pre-emergent herbicide. Pre-emergent herbicides are a powerful tool that lawn lovers use to neutralise seeds before they even get a chance to germinate, which is a great way to keep foreign flora out of your established lawn. As well as managing seasonal grasses like Poa Annua or wintergrass, a pre-emergent is also incredibly effective at managing undesirable weed outbreaks from plants like Pigweed/Purslane and others, whose seeds are easily spread and can germinate quite quickly.

Pre-emergent herbicides will often provide up to six months cover. They’re typically applied in Autumn to protect lawns through Autumn and Winter, and then again in Spring to cover Spring and Summer.

They are available in liquid form through products like Spartan or Barricade, or can be purchased in granular form through products like Onset GR or Oxafert, the latter of which has the added benefit of a slow release fertiliser.

Mowing regularly at the correct height for your grass type can also help suppress weed growth by encouraging a dense, healthy turf that outcompetes invasive species.

Whether you’re looking at managing an outbreak that you’ve just identified using a broadleaf or selective herbicide, or you think preventing weeds through the use of a pre-emergent herbicide would be more effective, you can purchase common post-emergent herbicides like Contra M Duo (not safe for Buffalo), and pre-emergent herbicides like Spartan, Barricade, Oxafert or Onset GR through the myhomeTURF online store.