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Common Lawn Weeds in Western Australia

As our biggest state, Western Australia is a vast land of contrasting climates, from Mediterranean in the south to tropical in the north.

In the south-west, the most populated area, the mild temperate climate has four distinct seasons and mostly winter rainfall.

The tropical north has a wet summer season and a dry winter, while much of the inland is semi-arid to arid.

This variation means you’ll find many different types of weeds trying to make themselves at home in your lawn, depending on where you are.

Because weeds are opportunists, they can grow in places other plants won’t, such as nutrient-deficient, compacted and poorly drained soils.

So it’s no surprise they thrive once they find themselves in a place that is cared for with water and fertiliser on tap.

And since most grass types suitable for WA lawns go dormant in winter, leaving space and nutrients available for weeds, that’s when you’re most likely to see them.

This means you’ll need to stay on top of tasks such as controlling weeds in your lawn in order to prevent them gaining a foothold and taking over your pride and joy.

Knowing where to start can be tricky, so we’ve put together a guide to common lawn weeds in WA.

Read on to learn more about the type of weeds you might encounter, how to identify them, the best methods for killing and preventing weeds, and which products we recommend.

Weed Types

There are two main weed types: Broadleaf weeds and Grassy weeds.

As the name suggests, Broadleaf weeds are plants that usually have a wider steam and leaf with a central vein that branches out.

The leaves can be segmented, in a variety of shapes and colours, and once broadleaf weeds mature many develop a tap root and produce visible flowers.

This usually makes them easier to distinguish from your lawn.

By contrast grassy weeds look more like your lawn, with shallow fibrous roots, long thin leaves that may have parallel veins, and what look like joints where the leaf meets the stem.

There’s also a third type of weed that’s neither a broadleaf nor a grass weed: Sedge.

Sedges, which are spread by both seeds and underground rhizomes, are extremely hardy weeds with triangular stems and can be difficult to control using common weed killers.

Weeds are also perennial or annual (and occasionally both).

A perennial weed is one that can lay dormant during winter but will regrow every spring from either rhizomes, bulbs or taproots, as well as from seeds in some cases.

Annual weeds are shorter-lived and usually sprout from seed, grow for a season, set seed and die off after a year.

There’s a guide to the most common lawn weeds here.

Identifying Weeds in WA

The WA climate provides habitats suitable for a huge number of different weeds.

Broadleaf weeds to look out for include

  • Burr Weed – A creeping weed that germinates in autumn and winter, it has serrated heart-shaped leaves divided into three. Stems are long and reddish, and the clustered flowers are small yellow and pea-shaped. Pods produce prickly burrs that dry out and spread seeds.
  • Bindii – A low-growing weed with carrot-like leaves, it has creeping hairy stems and in spring develops fruit that dry to become prickly burrs.
  • Cape Weed – A low-growing herbaceous annual, it starts as a rosette of deeply lobed leaves with whitish undersides. The daisy-like flowers have pale yellow petals and dark purplish centres made up of tiny tubular flowers.
  • Carrot Weed – Also known as Batchelor’s Button or annual Buttonweed, it grows in a thin mat with spindly stems and produces yellow or white button-like flower heads with no petals.
  • Catsear Weed – Often mistaken for Dandelions, it has hairy leaves and produces tall stalks that can have multiple small yellow flowers.
  • Chickweed – It has soft hairy stems and small oval leaves paired along the stems. Plants can produce tiny white flowers as soon as 4-5 weeks after germination.
  • Cudweed – Rosettes of grey-green, serrated-edged leaves, plants put up a stem in spring that supports small heads containing many flowers. Leaves and seedheads are often covered in fine white woolly fibres.
  • Dandelion Weed – The rosette of toothed leaves lays flat on the ground and plants put up a hollow stalk with a single bright yellow flower that becomes a puffball of seeds. Broken stems and leaves ooze a milky substance.
  • Dock Weed – A perennial with large oval green leaves that have a distinct mid rib. Tap roots can be very long, up to 90cm, and they produce large numbers of seeds. Often found growing near nettles and rubbing a crushed leaf on nettle stings can help ease the pain.
  • Dollar Weed – Also known as Pennywort, has bright green, glossy rounded leaves with wavy edges, that look like small lilypads. Tiny star-shaped white flowers grow in umbrella-like clusters.
  • Farmer’s Friends – Also known as Cobbler’s Pegs for the annoying black barbed seeds that attach to socks, trousers and animals, this is a short-lived plant with upright square stems and serrated paired leaves.
  • Fleabane – The rosette soon develops hairy upright branched stems. Lower leaves are bluntly toothed and the smaller upper leaves are narrower and more finely toothed. The flower heads turn white and puffy as they mature.
  • Khaki Weed – Also known as Khaki Burr, it is a low-growing perennial with oval-shaped leaves that grow in pairs on short stalks, and hairy reddish stems up to 60cm long. Mature flowers in the leaf forks develop sharp points and prickles.
  • Marshmallow – A semi-upright weed with a very deep tap root, it has rounded leaves with seven lobes, produces small mauve, pink row white flowers and reproduces by seed that can persist for up to 100 years. It can be poisonous to animals.
  • Onion Weed – The tall thin leaves and stems smell like onions or leeks when rubbed or broken. It puts out mostly white bell-shaped flowers at the top of a long stalk.
  • Oxalis – Also known as Creeping Oxalis, it has small heart-shaped leaves and produces tiny yellow flowers. It spreads by putting out runners and can regrow from the roots.
  • Plantain – Also known as Lamb’s Tongue, it has flat leaves with distinct veins and long, thin flowering stems that carry a dense brown cone-shaped seed head.
  • Soursob – Also known as Sour Grass and Bermuda Buttercup, Soursob is an extremely annoying fast-spreading weed. It has heart-shaped leaves, often with black dots, and produces bright yellow flowers with five petals.
  • Stinging nettle – The leaves have serrated margins and fine hairs which cause a sharp burning pain when brushed against the skin. They favour damp ground that’s been cultivated or left bare.
  • Summer grass – Also known as Crabgrass, this annual weed thrives in heat and humidity. Leaves are grey-green, stems can be red or brown and it spreads via runners. The seed heads contain small spikes.
  • Thistles – Herbaceous annual weeds that have spiky leaves and stems and mostly purple flowers.
  • White Clover – The bright green leaf on each stem is split into three leaflets with a paler moon-shaped mark. Flowers are made up of lots of small tubular flowers growing from the centre in a pom pom shape.

Grass weeds to look out for include

  • African Lovegrass – A hardy drought tolerant grass that grows in clumps and has stems up to 1.2m. Seed heads have many branches with lots of grey-green or purplish coloured elongated flower spikelets.
  • Barley grass – An annual species renowned for rapidly germinating after autumn rain, it grows to 45cm, has light green leaves that are often twisted, and produces hard seed heads.
  • Crabgrass – Looks like grass but has a wide leaf blade and sends out tough stems with fingers of seed heads at the tips.
  • Crows Foot Grass – A tufted short-lived grass with spreading or semi-upright stems up to 60cm long and narrow leaf blades. Seed heads can have up to 10 spikelets on each stem.
  • Onion Grass – Also known as Guildford Grass, it is a shiny, thin wiry weed that grows from a corm and produces small purple flowers with six petals.
  • Parramatta Grass, Rat’s Tail Grass – An upright, tussocky grass, with hairless stems that carry numerous densely packed flower spikelets and oval seeds that turn reddish brown as they mature.
  • Paspalum – A tufted grass with slightly folded leaf blades that grows from spring to autumn. The sticky seed heads are up to 10cm long and arranged along a thin stalk.
  • Wild Oats – An erect cool season annual grass with open branched nodding clusters of spikelets. Mature seeds are notorious for burrowing into the ears and skin of pets and causing abscesses.
  • Winter Grass – Most prevalent in winter and spring, it has a bright green leaf that is very soft when young and difficult to mow. It develops into clumps and the invasive roots will choke out your lawn.

Sedges to look out for include

  • Mullumbimby Couch – Grows year round, producing bright green leaves and pale green seed heads on three-sided stems up to 40cm long. It has long underground runners.
  • Nut Grass – Grows all year round, with long narrow leaves and puts out erect spikelets of red-brown or purple-brown flowers on triangular stems. It produces a network of creeping underground stems with small tubers.

How to Kill Weeds in Your Lawn

The best method of controlling weeds will depend on the type of grass in your lawn, the type of weed, how large the weeds are and how many there are.

There’s a guide to controlling Broadleaf weeds here and a guide for Grass weeds here.

Using a Herbicide

In general, contact herbicides such as glyphosate will give the quickest results. But because they’re not selective and kill anything they touch, including your lawn, you’ll need to be very careful with application.

Selective herbicides are usually safer for your lawn because they target specific weeds. If you’re still not sure what weed you’re working with, it’s best to seek advice from a lawn care professional.

Whenever working with herbicides always wear safety equipment such as gloves, protective glasses, boots and overalls, read the directions on the product label before use, and follow the instructions for application.

Recommended Products

Indigo Duke 100WG 100gm

Indigo Duke 100WG 100gm is a selective herbicide for controlling a range of broadleaf weeds and suppressing grass weeds. It can be used on Kikuyu, Buffalo and common or hybrid Couch grasses, but not Queensland Blue Couch or Zoysia grasses.

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Indigo Contra M Duo 1L

Indigo Contra M Duo 1L controls a very large range of broadleaf weeds. It is suitable for use on Zoysia, Kikuyu and Couch grasses, but cannot be used on Buffalo lawns.

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Syngenta Barricade 1L

Syngenta Barricade 1L is a pre-emergent liquid herbicide that prevents a range of grass weeds as well as several broadleaf weeds. It is suitable for use on Zoysia, Kikuyu, Buffalo and Couch grasses.

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Turf Culture Bow and Arrow 500mL

Turf Culture Bow and Arrow 500mL is a liquid herbicide with outstanding broadleaf weed control at very low application rates. It is suitable for use on Zoysia, Kikuyu, Buffalo and Couch grasses. Temporary discolouration can occur on Kikuyu, Carpet Grass and Queensland Blue Couch.

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Indigo Halo-Force 750WG 25gm

Indigo Halo-Force 750WG 25gm can be used for selective post-emergence control of Nut Grass and Mullumbimby Couch. It is suitable for use on Kikuyu, Couch and Buffalo lawns.

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TUFFWEED Liquid Glyphosate 1L

TUFFWEED Liquid Glyphosate 1L super concentrate is a non-selective herbicide that combats the toughest of all types of weeds, from broadleaf to grass, sedge and woody weeds. This includes weeds such as Blackberries, Thistles and Nut Grass.

You can browse the full range of products from leading lawn care brands in myhomeTURF’s online store here.

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When to Apply Weed Killer?

Plants must be actively growing, not under stress from pests, disease or waterlogging, and the leaves dry.

It’s best to tackle weeds before they flower or set seed to reduce the likelihood of the problem popping up again next year.

Avoid applying selective herbicide within two hours of rain or irrigation, or during very dry or frosty conditions.

If using glyphosate, don’t apply within six hours of rain and don’t disturb or mow the treated area for seven days after spot spraying.

How Long do Weed Killers Take to Work?

Selective Herbicide

It can take 7-10 days for the first signs, such as yellowing foliage, to appear and 4-6 weeks for the plant to die.

If there’s new growth or regrowth during that time, repeat treatment.

Keep people and pets off treated areas until the sprayed solution has dried and don’t feed clippings from treated areas to chickens or other animals.

Non-selective Herbicide

Glyphosate is a contact herbicide, so it will kill any plant it touches.

Effects can usually be seen in 3-7 days on annual weeds, and 2-3 weeks or longer on perennial weeds, depending on weather conditions after application by spot spraying or wick wiping.

Killing Weeds Without Damaging Your Lawn

Spot spray only with selective herbicides that are suitable for your grass variety.

In areas where weeds that spread via seed are a known problem, you could try using a pre-emergent herbicide in autumn to stop weed seeds from germinating in the following spring.

myhomeTURF recommends OxaFert, which is a combination product containing both fertiliser and pre-emergent herbicide.

You can browse the range of products from leading lawn care brands in myhomeTURF’s online store here

How to Get Rid of Weeds Naturally

The best way to avoid damaging your lawn is to prevent weeds from gaining a foothold by caring for your lawn properly, using the right kind of fertiliser, maintaining the optimum soil pH and mowing your lawn to the recommended height.

Other preventative measures include fixing any drainage or irrigation issues and stopping water from collecting in hollows in your lawn.

The second best method is to remove small plants by hand.

There’s a guide to Pulling Weeds From Your Lawn here.

Most larger weeds can be dug up with a sharp spade, taking care to leave a generous margin around and under the roots, as well as making sure to pick up any runners, tubers and bulbs that might be left behind.

Avoid cultivating weeds that spread via runners, tubers and bulbs – chopping them up will only spread pieces that can then grow into more new plants.

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