Creeping Woodsorrel

What is creeping woodsorrel?

Creeping woodsorrel is a low, spreading oxalis that turns up in lawns, beds, nurseries and greenhouses from coast to coast. creeping woodsorrel identification is easiest when you check three things together: clover-like leaves made of three heart-shaped leaflets, small yellow flowers with five even petals, and narrow upright seed pods.

It is one of the most stubborn small weeds a homeowner can face. One plant can fling thousands of seeds several feet, its stems root as they creep, and bits of stem and taproot left after weeding grow back. It sets seed even when mowed to a quarter inch, and UC IPM notes that extra fertilizer and water do not crowd it out; a more vigorous lawn just means a more vigorous woodsorrel.

Creeping Woodsorrel identification: what to look for

Check the leaf base and the flower. Clovers and medics have a small leafy stipule where the leaf stalk meets the stem, plus pea-shaped flowers; woodsorrel has neither. Its leaflets are notched like hearts, and its yellow flowers have five even petals.

• Leaves: Three heart-shaped leaflets on a long stalk, green to purple or maroon. They fold downward at night and in bright sun, and turn reddish and wilt under drought or heat.
• Stems: Prostrate stems creep above and below ground and root at the nodes, forming mats.
• Flowers: Bright yellow with five petals 1/8 to 1/3 inch long, one to five on slender stalks.
• Seed pods: Erect, hairy, cylindrical capsules with a pointed tip, 1/3 to 1 inch long, that split and throw seed when ripe.
• Seedlings: Two small round seed leaves come first, followed by true leaves already shaped like the mature heart-shaped leaflets.

Where it grows in the United States

USDA treats creeping woodsorrel as native to the lower 48. NC State lists it as hardy in USDA zones 4 through 8, and Extension services from North Carolina to California and Washington deal with it in lawns, beds and greenhouses. It is a major weed of container nurseries, so it often arrives in the soil of a new potted plant.

It grows in sun or partial shade wherever there is moisture, in clay, loam, sand or rich organic soil, from acid to alkaline. It establishes fastest in semi-shaded lawns and competes hard in bermudagrass and other warm-season turf while the grass is dormant. Extreme heat or cold slows it but does not kill it.

Creeping Woodsorrel look-alikes

A few plants get mixed up with it:

• Yellow woodsorrel (Oxalis stricta): A very similar oxalis with the same leaves and flowers, but it grows more upright instead of lying flat and rooting along its stems.
• Bermuda buttercup (Oxalis pes-caprae): A larger, upright oxalis that grows from bulbs. Its leaves are often dotted purple, its flowers reach 3/4 to 1 1/2 inches across on leafless stalks, and it dies back in summer.
• White clover (Trifolium repens): Has a small stipule at each leaf base, leaflets without woodsorrel's pronounced notch, and white to pale pink pea-like flowers in round heads.

How to get rid of creeping woodsorrel

Pulling, digging and mowing: Hand-weed before plants flower and set seed. Stems snap easily, so lift as much stem and taproot as you can and expect several rounds; carry pulled plants off the site. In beds, buried or mulched seed stays dark and will not sprout. You can also water and lightly cultivate to bring up a flush of seedlings, then destroy them. Before replanting a badly infested bed, solarize it under clear plastic for at least four weeks in June, July or August.

Cultural control matters most, because the right conditions keep it from coming back.

• Mulch beds 2 to 3 inches deep with organic mulch or landscape fabric topped with mulch; avoid sawdust-fine mulch that seeds can sprout on.
• Wash or blow off the mower after cutting infested areas so seed and clippings do not travel to clean turf.
• Inspect new plants, use seed-free potting soil, and skip nursery plants with oxalis growing in the pot.
• In a heavily infested bed, it can be easier to salvage the plants you want and start the bed over.

Herbicides: Preemergence products matter most because the seed bank drives an infestation. UC IPM lists dithiopyr, isoxaben, pendimethalin and prodiamine, applied in early fall when most seeds germinate and possibly again about eight weeks later; lawns can take up to three timings a year (early fall, midwinter, late spring). For plants already up in a lawn, triclopyr and fluroxypyr work best in cool-season turf. Triclopyr injures bermudagrass and kikuyugrass, so warm-season lawns rely on fluroxypyr or lower-strength blends of triclopyr with MCPA and dicamba. Mixes of 2,4-D, MCPP and dicamba usually need a second application, and 2,4-D alone does little. No selective product controls emerged woodsorrel in ornamental beds; careful spot treatment with glyphosate or glufosinate is the option there, and both injure any plant they touch. Use products labeled for the site and follow the label exactly. The label is the law. If you hire someone to spray, make sure they hold your state’s pesticide applicator license; the rules for each state are in our pesticide applicator license guide.

Keeping it from coming back

Stop seed first. Pull or treat plants before spring flowering, mulch beds so buried seed stays dark, and keep after new seedlings in fall, when most of them appear.

Keep it from hitching a ride. Check every nursery pot before planting, use clean soil in containers, and clean mowers, tools and boots after working in infested areas.

Questions we get about creeping woodsorrel

Similar weeds

Yellow Wood SorrelOxalis strictaBermuda ButtercupOxalis pes-capraeWhite CloverTrifolium repens