How To Remove Sedge Weeds From Your Lawn

Also known as Sedge Grasses, Sedge Weeds often look like grasses when they’re small, but they soon grow taller than your lawn and that’s when the differences become apparent.

Sedges are distinguishable by their stiff, narrow leaf blades, triangular stems and prolific seed heads.

They can reproduce by seed, from rhizomes, or both.

Common Sedge Weeds to look out for are:

• Flat Sedge – Also known as Tall Nut Grass, Tall Flat Sedge and Umbrella Grass, it grows from rhizomes and has erect stems up to 90cm, with long, thin, pointed leaves radiating from the top. Flat Sedge is regarded as an environmental weed in New South Wales, Victoria and Western Australia.
• Mullumbimby Couch – Also known as Short-leaf Flat Sedge and Perennial Greenhead Sedge, it grows year round, producing bright green leaves and pale green seed heads on three-sided stems up to 40cm long. It reproduces from both seed and long underground runners, and is regarded as an environmental weed in parts of Western Australia, Queensland, New South Wales and Victoria.
• 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.
• Umbrella Sedge – Also known as Umbrella Palm and Umbrella Papyrus, it is a long-lived reed-like plant with upright stems which usually grows 45-120cm tall. Often used in ponds and water features, Umbrella Sedge has escaped and become a common weed of waterways and wetlands across Australia. Umbrella Sedge reproduces mainly by seed but can spread from its short rhizomes to form large clumps.

Sedge Weeds can be difficult to eradicate because plants produce a large number of seeds and have an extensive system of underground rhizomes and tubers.

The main control options are mechanical and chemical methods, which are more likely to succeed if undertaken when plants are actively growing, not stressed and haven’t produced seed.

Using a Herbicide

Applied correctly, glyphosate can be effective on Sedge Weed, but as a non-selective herbicide it will poison everything it touches, including the surrounding lawn.

Products containing the active ingredient halosulfuron-methyl can be safely sprayed on many turf varieties to kill Sedge Weed, while others should only be used for spot application. This includes products containing MCPA that are marked on the label as being suitable for Paspalum, Nut Grass and Clover.

Depending on the maturity of the Sedge Weed plants and how large an area is affected, it may be necessary to spray more than once.

Always read and follow the safety directions and instructions on the product label before use.

Indigo Halo Force Herbicide 25gm

Tuffweed Liquid Glyphosate 1L

Always read and follow the safety directions and instructions on the product label before use.

The label will indicate the best time and method for applying the herbicide. This is often in late summer, from February to mid-April.

As a general rule, both the weeds and your lawn should be actively growing, not stressed by too much or too little moisture.

The weather should be not too hot, still and with no rain – or irrigation – within a few hours before or after application.

How Long does Herbicide Take to Work?

Signs of successful weed control with a selective herbicide containing the active ingredient halosulfuron-methyl start with a gradual yellowing of foliage and seed heads, followed by drying and browning of the plant.

Initial symptoms may take 7-10 days to be noticeable, with full effects occurring 4-6 weeks after treatment.

If there’s new growth after this time, a follow up treatment might be required.

Visible effects from glyphosate application include gradual yellowing and wilting of the plant.

This advances to complete browning above the ground and deterioration of underground plant parts.

These effects take 3-7 days for annual weeds, and 2-3 weeks or longer on perennial weeds, depending on weather conditions after spraying.

There will be times when manual removal of weeds is the best, cheapest or safest method of control.

When weeds are small or there’s only a few of them, it makes more sense to pull them up by hand than going to the trouble of mixing and spraying a batch of herbicide then properly disposing of the leftover mixture.

Other scenarios include new lawns, which are more vulnerable to chemical damage than established lawns, and when weeds are growing in Soft Leaf Buffalo lawns which are more sensitive to herbicides than most other grasses.

Take care not to break Sedge Weeds off at ground level because new plants will shoot up from the underground rhizomes.

The best way to tackle them is to target small plants before they’ve had a chance to develop an extensive rhizome network under the ground.

Soften soil with water and gently loosen it with a garden fork before you carefully follow the roots, taking care to collect any rhizomes or tubers along the way.

If that takes too long, or there are too many plants, use a sharp spade to dig them up when small.

Leave a generous margin around the Sedge Weed and make sure you go deep enough to capture any rhizomes or tubers.

Whatever you do, don’t put Sedge Weeds into the compost heap, because they will go wild.

You can read our complete guide to pulling weeds from your lawn here.