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Why Your Lawn Goes Dormant In Winter

Why Your Lawn Goes Dormant In Winter

If you've ever stepped outside on a cold July morning, stared at your patchy, straw-coloured lawn, and wondered what on earth went wrong, you're not alone. The truth is, your lawn dormant in winter is doing exactly what it's supposed to do. Nothing's dead. Nothing's broken. It's just your warm-season grass having a well-earned rest, and the best thing you can do right now is understand why, and plan ahead for spring.

Close-up of a warm-season lawn gone golden brown and straw-coloured through winter dormancy

Why Warm-Season Grasses Go Dormant in Winter

Australia's most popular lawn varieties (couch grass, kikuyu, buffalo, and zoysia) are all warm-season grasses. They thrive when temperatures are high and the sun is strong, but once the mercury drops and days shorten, they pump the brakes.

Couch grass (Cynodon dactylon) growing as a fine-bladed green sward, photographed in Brisbane
Couch grass in active growth. Fine blades and a dense, low-growing habit. This is what it looks like before winter takes the colour out of it.
Kikuyu grass (Pennisetum clandestinum) close-up showing broad blades and creeping runners
Kikuyu. Broader blades and aggressive runners, and it tends to hold colour a little longer than couch in mild coastal areas.

The key driver here isn't just air temperature. It's soil temperature and lawn growth. Once soil temperatures consistently fall below around 12–15°C, warm-season grasses dramatically slow their metabolic processes. Photosynthesis winds down, root activity decreases, and the grass enters a state of dormancy. Couch grass winter dormancy is particularly noticeable: that lush green sward can turn a dull beige almost overnight once conditions cool.

Infographic showing warm-season lawn dormancy by soil temperature: below 12C deep dormancy, 12 to 15C slowing, above 15C active growth and the spring renovation window, with winter do-nots and the five renovation steps
Soil temperature, not the calendar, is the reliable trigger. Save or print this for the shed wall.

Kikuyu dormancy follows a similar pattern, though kikuyu can hang on a little longer in milder coastal climates. Either way, the diagnosis is often simple: it's winter, and not a lot will happen until it begins to warm up again. As one seasoned lawn enthusiast put it, if you've got couch and it's winter, let it do couch stuff until spring.

Heavy morning frost coating grass blades, the cold conditions that push warm-season turf into dormancy

What to Watch Out for While Your Lawn Sleeps

Just because your grass is dormant doesn't mean your lawn is problem-free. Winter brings its own set of challenges.

Winter weeds are the big one. Poa annua (winter grass) is the most notorious: a light-green, clumping annual grass that absolutely loves the cold and will happily colonise your dormant lawn while your warm-season turf can't compete. Broadleaf weeds like bindii, clover, and capeweed also take advantage of the gap.

Poa annua (winter grass) showing fine light-green leaves and branching seed heads in a clumping habit
Poa annua, or winter grass. Light-green, fine-leaved clumps with branching seed heads. It thrives in exactly the conditions your lawn cannot.
Capeweed (Arctotheca calendula) showing pale yellow daisy flowers with dark centres above a flat rosette of deeply lobed leaves
Capeweed. Pale yellow daisy flowers with a dark centre, sitting above a flat rosette of deeply lobed leaves that smothers turf underneath.

Fungal disease is another winter lawn concern, particularly in regions that experience wet, overcast weather. Cool, damp conditions with poor airflow create ideal environments for fungal pathogens to establish in turf. Keep an eye out for unusual patches, rings, or discolouration that doesn't match typical dormancy browning.

Mowing height in winter matters more than many people realise. Don't be tempted to scalp a dormant lawn. Raise your mowing height slightly and mow less frequently. Cutting too low stresses already-dormant turf and can expose the soil to weed germination.

Mowing a lawn with the mower deck set high, the correct approach for dormant winter turf
Lift the deck over winter. A higher cut protects the crown and keeps light off bare soil where weed seed is waiting.

Should You Fertilise in Winter?

Short answer: no. Applying a nitrogen-heavy lawn fertiliser to a dormant warm-season lawn is largely a waste of product and money. The grass isn't actively growing, so it can't take up nutrients efficiently. Worse, excess nitrogen sitting in the soil over winter can promote weed growth and contribute to fungal issues.

Patience is the real fertiliser during winter. Save your quality lawn fertiliser for spring, when soil temperatures begin to climb back above 15°C and you start to see that first flush of green growth returning to your couch or kikuyu. That's when the grass is ready to respond and you'll get real value from feeding.

Timing Your Spring Lawn Renovation

Spring is when the real work begins. A spring lawn renovation is your chance to reset the lawn after winter and set it up for a cracking summer. Here's how to approach it:

  1. Wait for consistent warmth. Don't rush. A couple of warm days in late August doesn't mean spring has arrived. Wait until soil temperatures are reliably above 15°C before you start aerating, scarifying, or top dressing.
  2. Control winter weeds first. Before your warm-season grass fully wakes up, tackle poa annua and broadleaf weeds. This is also the ideal window to apply a pre-emergent spring treatment to prevent summer weed seeds from germinating as temperatures rise.
  3. Aerate and top dress. Compacted soils from winter foot traffic respond well to aeration. A light top dressing with quality sand or soil mix helps level the surface and encourages lateral growth. For the full timing detail on both jobs, see our spring lawn scarifying and top dressing timing guide.
  4. Feed strategically. Once growth kicks off, apply a balanced granular or liquid fertiliser to support recovery. Follow up with a soil wetter to ensure nutrients and water are penetrating efficiently. Sandy or hydrophobic soils can be particularly stubborn after a dry winter.
  5. Adjust your mowing gradually. As the lawn thickens up, gradually bring your mowing height back down to your preferred summer height. Don't drop it all at once.z

Recommended Products

Here are a few products to have ready for your spring lawn renovation:

Barricade Pre-Emergent Herbicide 250mL – Syngenta is a professional-grade pre-emergent herbicide that provides long-lasting residual control of grassy and broadleaf weeds in established turf. Apply in early spring before weed seeds germinate to get ahead of summer annual weeds.

Bow and Arrow Herbicide 500mL is the industry standard for broadleaf weed control in Australian turf. If winter weeds like bindii and clover have crept into your lawn, Bow and Arrow is an excellent post-emergent option to clean things up before your warm-season grass takes off.

Lawn Addicts Fertech Complete Liquid Fertiliser is an NPK 18:0:12 liquid fertiliser with added iron and slow-release nitrogen, ideal for that first spring feed when your couch or kikuyu is waking up and hungry for nutrients.

EcoGrowth Eco-Wet 1L bottle is a quality soil wetting agent to ensure water and fertiliser penetrate efficiently once you start your spring program. Perfect for hydrophobic soils that have tightened up over winter.

Sunlight breaking through lush green grass blades, the spring green-up that follows winter dormancy

Winter can be a frustrating time for lawn lovers, but understanding warm-season grass dormancy takes the stress right out of it. Rest easy, plan your spring program, and your lawn will reward you for it.

Ready to get prepared for spring? Visit nutrienwaterstore.com.au to browse our full range of lawn care products and get your order sorted before the growing season hits.

Image credits: Hero dormant lawn and patchy dormant turf photos by Engin Akyurt via Pexels. Frost on grass photo by Keagan Henman via Unsplash. Closing spring green-up photo by Aniket Bhattacharya via Unsplash. Mowing and pre-emergent spraying photos by Gustavo Fring via Pexels. Core aeration photo by Naoki Suzuki via Unsplash. Couch grass photo by John Robert McPherson (Wikimedia Commons, CC BY-SA 4.0). Kikuyu photo by Forest & Kim Starr (Wikimedia Commons, CC BY 3.0). Poa annua photo by Sam Kieschnick (Wikimedia Commons, CC BY 4.0). Capeweed photo by Xemenendura (Wikimedia Commons, CC BY-SA 3.0). Soil temperature timeline produced in-house by Nutrien Water. Product imagery courtesy of Nutrien Water.

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