G’day, Nikolai here from The Lawn Firm. If you see tiny yellow flowers and clover-like leaves spreading through your grass, that’s creeping oxalis. I deal with it across Canberra every year. It spreads fast, sits low, and crowds out healthy turf. Here’s my simple plan to stop it.

What creeping oxalis looks like

Leaves: Three heart-shaped leaflets, smaller and finer than clover
Flowers: Small, bright yellow, held above the leaves
Habit: Low, spreading mats that root at the nodes
Roots: Fine, shallow, quick to re-establish if fragments remain

Why oxalis takes hold in Canberra

Thin turf after summer creates gaps for colonisation
Low mowing or scalping opens the canopy
Compacted clay weakens roots and helps weeds win space
Dry, hydrophobic soil leaves bare patches that oxalis exploits

When oxalis is most active

You notice new growth from late winter, with peak spread in spring and summer when the plant flowers and sets seed. I aim to act before flowering.

Fast checks I use on site

Leaf size test: Oxalis leaflets are smaller and more delicate than clover
Flower check: Yellow, five-petal flowers (clover is usually white or pink)
Spread pattern: Runners that creep and root at nodes
Pull test: Small clumps lift easily in thin areas but regrow if roots remain

Prevention beats cure

Raise mowing height to shade soil and protect crowns
Feed on a seasonal schedule so turf stays dense
Core aerate compacted areas in spring or autumn
Use wetting agents in warm months to stop dry patch gaps
Overseed and top dress thin zones to close space

Control once oxalis appears

Hand removal (small patches): Loosen the soil after rain or a light soak. Lift the plant and as much root as possible. Bag and bin it.
Targeted treatment (wider spread): Use a selective approach suitable for broadleaf weeds. Apply on actively growing oxalis. Avoid blanket spraying stressed turf.
Timing tip: Treat before or early in flowering to reduce the seed bank.

Aftercare to stop it returning

Rake out dead material so grass can fill in
Top dress 5–8 mm with fine sandy loam to even scars
Overseed to rebuild density and block light to the soil
Light fertilise to support steady recovery
Water deeply, not often to drive roots down

Common mistakes I fix

Scalping to “cut it out” – this weakens turf and invites more oxalis
Leaving root fragments during hand-weeding
Random spraying with the wrong product type or timing
Skipping aeration on compacted clay soils

My ACT timing guide

Late winter / early spring: Feed, raise mowing height, treat early oxalis
Spring: Aerate, overseed, and top dress thin areas
Summer: Use wetting agents, water deeply, maintain mowing height
Autumn: Strengthen roots, close gaps, and prep for winter

DIY or call The Lawn Firm?

You can hand-weed small patches and adjust mowing and watering. For full-lawn outbreaks, timing and technique decide the result. I assess the site, apply the right control, and line up aeration, overseeding, and nutrition so oxalis loses its foothold, and your grass wins the space back.