Catsear (Hypochaeris radicata)
Catsear is one of the most common flat weeds found in New Zealand lawns. It’s a perennial weed that forms a rosette close to the ground and produces tall, branching stems topped with yellow daisy-like flowers. Because of its appearance, it’s often mistaken for dandelion or hawkbit, but catsear is its own species and can be even harder to remove once established.
It thrives in low-fertility soils and compacted areas, often popping up where grass has thinned or dried out. Its deep taproot allows it to survive drought and mowing, and it spreads both by seed and through regrowth from root fragments. Once it settles in, catsear can quickly take over thin lawns, creating rough, uneven patches that ruin the look of your grass.
Identification
Catsear grows as a rosette with hairy, lobed leaves that sit flat to the ground. This is one of the easiest ways to tell it apart from dandelion, which has smooth leaves. The undersides of the leaves are also slightly paler and covered in fine hairs.
When flowering, catsear produces multiple branching stems, each with small yellow flower heads. This is another key difference—dandelion and hawkbit have single, unbranched flower stems, while catsear and hawksbeard have several. Unlike hawksbeard, however, catsear’s flower stems are bare and leafless.
After flowering, the seeds are carried away by the wind on fluffy pappus, just like dandelion seed heads, helping it spread easily through lawns and neighbouring areas.
Why It’s a Problem in Lawns
Catsear competes strongly with grass, particularly in dry, compacted, or under-fed lawns. Its broad rosettes block sunlight and prevent grass from filling in, and its deep roots make it tough to remove completely by hand.
Because it survives mowing and produces seed throughout much of the year, it can quickly re-establish after removal. A lawn full of catsear usually indicates poor soil fertility, compaction, or neglect, so fixing those conditions is just as important as weed control.
Control in Home Lawns
Catsear can be managed effectively with the right herbicide program and improved lawn health.
Best control methods:
- Physical removal: Dig out individual plants using a weeding knife or narrow spade, making sure to remove as much of the taproot as possible. Even small root pieces can regrow.
- Chemical control: Use selective herbicides such as triclopyr/picloram (NZLA Gold) or 2,4-D/dicamba blends for reliable control. Clopyralid (NZLA BWC) can also be used at higher rates. Apply when the weed is actively growing in spring or autumn for best results.
- Avoid composting treated clippings: These herbicides leave residues that can damage garden plants if used in compost within a few months of spraying.
- Cultural improvement: Aerate compacted soil, apply balanced fertiliser, and keep the lawn thick and healthy. Well-fed grass will outcompete new seedlings and limit regrowth.
Prevention Tips
- Fertilise twice a year to maintain strong grass growth and reduce bare spots.
- Aerate heavy or compacted areas, especially high-traffic zones.
- Reseed thin areas promptly after weed removal to prevent reinfestation.
- Mow regularly but avoid scalping, as low mowing encourages rosette weeds to spread.