Creeping Woodsorrel (Oxalis corniculata) is a pervasive weed that challenges homeowners and gardeners. This low-growing plant quickly colonizes lawns, flowerbeds, and pavement cracks, often surviving year-round in milder climates. Successful eradication requires a targeted, multi-step approach addressing the plant’s unique biological advantages and aggressive growth habit. This guide outlines the necessary strategies to identify, remove, and prevent the return of this pest.
Identifying Creeping Woodsorrel and Why It Is Difficult to Control
Creeping woodsorrel is easily recognized by its trifoliate leaves, which feature three heart-shaped leaflets resembling clover, often displaying a distinctive green to reddish-purple color. Small, bright yellow flowers with five petals appear throughout the warmer months, leading to the seed capsule. These elongated pods are filled with tiny seeds and, when mature, they physically rupture, forcefully ejecting seeds up to 16 feet away.
The plant is difficult to control due to its robust root system and aggressive spread. As a perennial, it uses prostrate, above-ground stems called stolons, which root at the nodes to form new plants. It also develops a deep taproot and underground rhizomes, meaning clipping the top growth leaves behind viable pieces that can readily regenerate, ensuring a continuous cycle of re-infestation.
Manual and Cultural Removal Strategies
For small infestations, non-chemical control can be effective with precision and persistence. Hand-pulling is a viable option, but the entire plant must be removed, including the taproot, stolons, and rhizomes. This task is easier when the soil is moist, reducing the likelihood of brittle root pieces breaking off and remaining in the ground.
Cultural controls alter the environment to make it less hospitable for the weed. Applying a heavy layer of organic mulch, 2 to 3 inches deep, suppresses seed germination by blocking light. For severe infestations without desirable plants, soil solarization—covering the soil with clear plastic sheeting during hot weather—can destroy dormant seeds. Maintaining a dense, healthy lawn through proper mowing and fertilization is also a strong defense, as vigorous turf crowds out the woodsorrel.
Effective Herbicide Treatments
Chemical control is necessary for widespread or persistent infestations, using pre-emergent and post-emergent herbicides. Pre-emergent herbicides are applied before seeds germinate, creating a chemical barrier that prevents seedlings from emerging. Active ingredients such as dithiopyr, isoxaben, pendimethalin, or prodiamine are effective in turfgrass areas. These products are most beneficial when applied in the spring and fall, coinciding with peak germination periods.
For existing, actively growing plants, post-emergent herbicides are required. Selective herbicides formulated for turfgrass often include combinations of active ingredients like triclopyr, dicamba, or 2,4-D, which target woodsorrel without harming established lawns. These systemic herbicides are absorbed through the leaves and transported throughout the plant, ensuring complete kill.
A non-selective herbicide containing glyphosate can be used for spot treatments in landscape beds or on hardscapes. When applying any chemical, target young plants, as they are more susceptible than mature ones. Always follow the product label instructions carefully, especially concerning safe application temperatures, to prevent damage to surrounding vegetation.
Stopping Woodsorrel From Coming Back
Long-term management is necessary to prevent re-establishment because seeds remain viable in the soil for extended periods. Continuous monitoring for new seedlings is important, and young plants should be removed immediately before they flower and produce seed capsules. Reliance on mowing alone is insufficient for control, as mowed woodsorrel can still set seed.
Sanitation practices reduce the spread of seeds and plant fragments. After working in an infested area, wash or air-spray mowing equipment and gardening tools to remove attached seeds or stolon pieces before moving to weed-free areas. Addressing small gaps and cracks in walkways or patios with sealant or non-selective spot treatments will also eliminate common refuge points where woodsorrel frequently takes hold.