Mallow (Malva spp.)
Mallow is a common broadleaf weed found throughout New Zealand, particularly in lawns, gardens, and waste areas. The term “mallow” refers to several related species in the Malva genus, including small-flowered mallow (Malva parviflora), dwarf mallow (Malva neglecta), French mallow (Malva nicaeensis), and large-flowered mallow (Malva sylvestris). While there are subtle differences between them, they all behave similarly in turf and are controlled in the same way.
Mallow can act as either an annual or a short-lived perennial depending on conditions. It’s tolerant of drought, compacted soils, and low fertility—making it well-suited to thin or neglected lawns. The weed often grows flat to the ground, forming wide mats that smother surrounding grass. Once mature, it becomes woody at the base and develops a strong taproot, making hand removal difficult.
Identification
Mallow has rounded, crinkled leaves that resemble those of geranium. Each leaf has five to seven shallow lobes, giving it a scalloped, fan-like appearance. The leaves are usually soft and slightly hairy, with long stems attaching them to the main crown.
The plant typically grows low to the ground (around 20–30 cm), but in favourable conditions it can reach up to a metre tall. In lawns, it forms flat rosettes that escape mowing blades. During spring and summer, it produces small pink or pale purple flowers, followed by a ring of seed capsules (known as “nutlets”) that split apart when dry.
Mallow can be distinguished from similar weeds like creeping mallow or geranium by its fibrous stems, larger leaf size, and the way the leaves alternate up the stem.
Why It’s a Problem in Lawns
Mallow competes aggressively with grass, especially in compacted or dry areas. Its spreading habit shades the soil and prevents new grass from establishing, while its deep taproot allows it to survive long dry spells and regrow after mowing or partial removal.
It’s also tolerant to many common herbicides, making it harder to control than most broadleaf weeds. Once mature, it develops a tough, woody crown that can survive mowing, trampling, and even light herbicide applications. Its presence is often a sign of poor lawn fertility or neglected soil structure.
Control in Home Lawns
Mallow can be controlled, but persistence is key. Early treatment—while the plant is young and actively growing—gives the best results.
Best control methods:
- Physical removal: Hand-pull or dig out young plants, making sure to remove the full taproot. Older plants are harder to remove cleanly and may regrow from root fragments.
- Chemical control: Use selective broadleaf herbicides containing 2,4-D/dicamba (e.g. Banvine) or triclopyr/picloram (NZLA Gold) for strong control. These are effective on both young and mature plants. Apply when the weed is actively growing and avoid mowing for several days before and after treatment.
- Seedling control: In very young stages, herbicides containing flumetsulam can help suppress seedlings before they mature.
- Cultural management: Improve soil health through aeration and fertilising, as mallow thrives in compacted, nutrient-poor soils. Thick, healthy grass cover will crowd out new seedlings.
Prevention Tips
- Feed the lawn regularly with nitrogen-rich fertiliser to maintain dense grass growth.
- Aerate compacted areas annually to improve drainage and root development.
- Avoid overwatering, as mallow can tolerate both wet and dry conditions.
- Reseed thin or bare patches promptly after weed removal.
- Monitor through summer and autumn—mallow can germinate year-round in warm conditions.