Winter Grass (Poa Annua) in Lawns

Winter Grass (Poa Annua) in Lawns

Winter Grass (Poa Annua) is a highly common weed in most lawns throughout Australia. It has a bright green leaf which is very soft in it’s early life cycle, and will most commonly appear at the beginning of winter and can often last until the New Year.

It’s bright green leaf makes the grass very apparent as a weed in home lawns, and it never mows very well, neither with a rotary or cylinder mower.

The weed can become a real problem over time as the many generations create more and more root systems, which will keep filling the soil like spiders’ webs. The root systems are very intensive and will eventually fill the soil and choke out the lawn’s own root system.


How to Kill Winter Grass

The herbicide for Winter Grass is the most unique amongst most other herbicides. This is because it acts on the root system of Winter Grass rather than on the leaf system like other poisons.

Winter Grass herbicide can be bought in a concentrated form in a small or large bottle. It is then mixed with water in a spray bottle and sprayed onto the lawn as per the manufacturer’s instructions. Alternately, a pre-emergent granular herbicide such as OxaFert can be used, this combination product also acts as an effective fertiliser. Always check the herbicide’s label to make sure it is suitable for your lawn variety.

Because this herbicide works on the root system, it must be watered immediately into the lawn after application.

One of the most important factors in controlling Winter Grass is to treat it as early as possible in its lifecycle. The more Winter Grass matures, the more difficult it is to kill, and it can often resist weed sprays. The other reason to treat this weed early is to kill it off before it has a chance to produce a new generation of weed seeds, which will only create more Winter Grass in the years to come.

Expect to treat Winter Grass for a few years running, as the seed banks will take some time to deplete their stocks in the soil.

Pre-Emergent Control of Winter Grass

Winter Grass needs to be treated as early in its life cycle as possible, in fact, the best time to treat Winter Grass is before it is even seen.

This is when the Winter Grass seeds have germinated in the soil but have yet to emerge into the lawn’s surface.

This may seem like a tricky act, but it really is very easy.

If you have had Winter Grass on your lawns in previous years, then you will most certainly have it this year.

So, if Winter Grass is expected, you simply apply the herbicide in May, knowing that the weed has already germinated, around April, within the soil.

myhomeTURF recommends OxaFert, which is a combination product containing both fertiliser and pre-emergent herbicide. Always read the safety directions and instructions on the product label before use.


Post-Emergent Control of Winter Grass

Post-emergent control of Winter Grass is also an option once the weed has already germinated. 

The post-emergent herbicide targets the Winter Grass root system and stunts the growth of the weed.

However, unlike pre-emergent herbicide, post-emergent herbicides can not control new generations of the weed.

myhomeTURF recommends Poachek, which is a soluble liquid post-emergent herbicide. Always read the safety directions and instructions on the product label before use.

Note: Poachek is not suitable for use on Kikuyu grasses.


myhomeTURF also recommends Indigo Duke, which is a post-emergent liquid herbicide. Always read the safety directions and instructions on the product label before use.

Note: Indigo Duke is not suitable for use on Zoysia grasses.


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