Managing Oxalis Weeds: How To Get Rid Of Oxalis Weeds In The Lawn

Oxalis looks a bit like a miniature clover plant, but it bears tiny yellow flowers. It is occasionally grown as a groundcover but to most gardeners it is a tenacious and annoying weed. The persistent plant is found in many parts of the world and rises from stem fragments and tiny bulbils. Managing Oxalis weeds takes determination, bulldog-ish stubbornness and inflexible resolve. Oxalis weed control also takes time, as each and every bulbil is removed or becomes ineffective.

Oxalis Weed Facts

Buttercup oxalis, wood sorrel or sourgrass. By any name the weed is Oxalis, a tear your hair out dogged weed that can take years to remove from your garden. The low growing plant can re-establish from just a tiny stem fragment, fragile breakable rhizomes or bulbils. It produces volatile viable seed and also relies upon bits of itself being transported by animals, or us, to establish itself in almost any type of soil. Learn to get rid of Oxalis weeds with some easy steps and save yourself time and energy as well as sanity.

Oxalis is a perennial weedy groundcover, which spreads through interlocking rhizomes that are easy to break apart. Each rhizome will eventually produce tiny bulbils. The seeds are also prolific and are ejected when ripe from tiny seed pods that look like mini okra. Anywhere the stem touches the ground the plant can root, potentially producing more and more plants. It also forms a fleshy taproot and an extensive branching root system. Managing Oxalis weeds can be a huge challenge due to all the tough root system and the different methods the plant has to reproduce itself and persist.

Types of Oxalis Weeds

There are over 800 species of Oxalis. Two of the most common types of Oxalis weeds are creeping wood sorrel and Bermuda buttercup. Both of these are found across the Northern hemisphere and are persistent pests in the landscape.

  • Bermuda buttercup is most likely to grow in full sun in coastal areas.
  • Creeping wood sorrel is found in either sun or shade in moist locations.

Both spread by rhizomes and stem fragments as well as seed and bulbils. Leaves are heart shaped in both plants and held in pairs of three. One of the more terrifying Oxalis weed facts for those of us fighting this plant, is that it can bloom and set seed at any time of the year.

Managing Oxalis Weeds

The word “management” may seem like a cruel joke if you have done battle with Oxalis before. Oxalis weed control can be achieved with an herbicide. Use a formula marked for broadleaf plant control such as Dicamba, 2,4D, Clopyralid, or Tiplopyr. These are serious chemicals and you must follow all instructions and apply before the plant sets seed.

An organic option is to use liquid chelated iron. This may work in grass, which can tolerate the iron whereas the weed cannot.

The most non-toxic way is determined hand digging, but this can take several seasons to get all of the Oxalis out of your garden. Pulling is not effective, as it will leave behind fragments of rhizome, stem and bulbils, which will simply establish new plants.

Oxalis Control: How To Get Rid of Oxalis

Oxalis is an annual or perennial plant that some people find pleasant to look at because of their delicate clover-like leaves and attractive blooms. If you’re trying to keep a uniform lawn, though, Oxalis can be one of the most annoying and difficult weeds to eradicate.

Oxalis is a perpetual weedy groundcover, which spreads via interlocking underground stems (or rhizomes) that are easy to separate. Oxalis has plentiful seeds which drop when ready from little seed cases that look similar to okra. Anywhere the stem touches the ground the plant can root with the potential of creating a large number of plants.

This noxious weed usually dominates in areas of the garden planted with low ground covers. When Oxalis grows alongside ground covers it is virtually impossible to get rid of without damaging the surrounding desired grass. Managing Oxalis can be difficult because of its tough root system and the different methods the plant has to reproduce itself and persist.

If you are having a problem with Oxalis on your lawn, our DIY Oxalis treatment guide can help. The directions below were recommended by our lawn care experts and will show you how to properly eliminate Oxalis from your lawn or garden.

Identification

Oxalis, also known as wood sorrel, looks very similar to another weed called Clover, with the signature three-parted rounded leaves. Oxalis can grow between 6 to 12 inches tall and have unique shamrock-shaped leaflets in various color combinations including ones with speckles. Oxalis leaves arise from a creeping rootstock and unlike Clover, Oxalis bears flowers which vary in color from yellow to white or purple, depending on the species. At night, the leaflets fold back and droop.

Use the description and image above to help you to properly identify oxalis on your property. If you are not totally sure, contact us and send us a photo of your weed and we will identify it for you and suggest treatment options.

Inspection

Where to Inspect

Oxalis thrives in partial shade and moist, poorly-drained soil but can spring up in almost any type of soil. Oxalis grows low to the ground and even after hand-pulling and mechanical control methods, it can return from just a small left behind stem fragment, fragile breakable rhizomes or bulbils.

What to Look For

You will be able to easily notice Oxalis on your property due to its shamrock-like leaves and if mature, it’s bright flowers. It is often seen forming thick clusters of groundcover in open areas on lawns and flower beds.

Treatment

Before weed treatment, please first make sure you have on the necessary PPE (gloves, mask, glasses) prior to handling any herbicide chemicals.

If Oxalis is appearing on your lawn, apply Martin’s TopShot. TopShot is our go-to herbicide for Oxalis control because of its affordability, ease of use and the fact that it is labeled for both warm- and cool-season grasses.

Apply Topshot in the late spring when the weeds are younger and smaller. Herbicides are less effective the older and more mature the weed gets. It may need to take multiple applications to get total control of this pesky weed, especially if you have a significant outbreak.

Step 1: Mix and Apply TopShot

Martin’s TopShot comes with 2 pre-measured ampules of product that each cover 2,500 sq. ft. of area. Adding a surfactant to the TopShot mixture such as Alligare 90 can enhance the effectiveness of the Topshot. Apply Alligare 90 at a rate of 4 Teaspoons per 1 gallon of solution.

Measure the square footage of your yard and then input the appropriate amount of TopShot in a pump sprayer or hose-end sprayer by squeezing the ampule into the sprayer mixed with water. Add surfactant to the Top Shot mixture at a rate of 0.5 to 4 tsp. per gallon of the solution and agitate until well mixed.

Apply the TopShot solution to the Oxalis on a fan tip nozzle spray setting to spray a fine mist that will evenly coat the weed. Noticeable results occur in 1 to 3 weeks.

Prevention

To prevent Oxalis from popping up in lawns, make sure that you maintain thick, healthy turf. Fill up any bare spots in your lawn with sod or seed because that is where Oxalis weeds will eventually spring up. Mulch garden beds with a two- to three-inch layer of organic mulch to prevent the weed from making a home amongst your perennials or vegetables. Without sunlight, the weed seeds cannot germinate.

A pre-emergent (such as Nitrophos Barricade) may be a good preventative measure, especially if the problem is an annual occurrence. Oxalis thrives in open, fertile soil, which is why it can such a recurring problem where the soil is so favorable to growth.

Key Takeaways

  • Oxalis is a fast-growing and extremely aggressive annual weed known for its tendency to take over lawns and gardens with its low growing ground cover.
  • Our top recommendation for treating Oxalis is Martin’s TopShot due to it’s ease of use, affordability and effectiveness on both warm-season and cool-season grasses.
  • A pre-emergent herbicide like Nitrophos Barricade can be applied to your lawn before the growing season to prevent Oxalis seeds from sprouting.

Oxalis Control

Oxalis or yellow woodsorrel (Oxalis stricta) is a common cool-season perennial weed that persists almost year-around in Southeastern lawns. It grows sporadically in landscape beds among shrubs and flowers, in vegetable gardens, and is known to pop up occasionally in container plantings.

Oxalis (O. stricta) can be pulled up by hand easily when found growing intermittently in landscape beds.
LayLa Burgess, © 2017 HGIC, Clemson Extension

Oxalis has an upright form with slightly hairy stems that branch from the base of the plant at almost ground level. Erect stems give rise to an alternate leaf arrangement. Oxalis stricta leaves are green, whereas the commonly found creeping woodsorrel (O. corniculata) has green to purple leaves. Oxalis leaves are distinctly trifoliate (leaflets of three) with a heart shape similar to the leaves of clover. Often the leaves will fold along the midrib and hang down in the heat of summer, in intense light, and at night. Oxalis produces 5-petalled, yellow flowers singly or in clusters on a branched stalk. Small okra shaped fruiting capsules are formed that contain minute seeds. When mature, seeds are ejected from the capsule for a considerable distance from the parent plant. Oxalis reproduces primarily by seed but may spread by underground slender rhizomes.

Oxalis (O. corniculata) often invades container flowerpots but can be easily removed by hand pulling. Oxalis produces a 5-petalled, yellow flower followed by a seed capsule.
LayLa Burgess, © 2017 HGIC, Clemson Extension

Oxalis grows under a variety of conditions, but prefers moist fertile soils and full sun. It will tolerate shady areas. All plant parts are poisonous because of the production of soluble oxalate, but are only mildly toxic and generally causes little problem if ingested.

Cultural Control

Oxalis flowers and produces seeds heavily in the spring and summer, but can produce both all year long. Small plants can easily be handpicked or dug as they appear before they flower or form seed. Removal of all vegetative portions of the plant, including roots and rhizomes, is important. Rhizomes can be easily removed when soil is moist. Do not place the weeds with seeds in compost bins for reuse in the landscape.

A light layer of mulch in landscape beds and around flowers and shrubs will aid in preventing further germination of oxalis seeds. The seeds require light for germination, so limiting light to the seedbed with mulch will reduce the numbers of new oxalis plants.

Oxalis forms a fruiting capsule that contains multiple seeds.
LayLa Burgess, © 2017 HGIC, Clemson Extension

Maintenance of healthy, dense lawns will create less space for oxalis to invade. Lawn maintenance should adhere to fertilizer and lime recommendations obtained from soil test results combined with proper mowing height and frequency requirements. For more information on soil testing, see HGIC 1652, Soil Testing.

Chemical Control in Landscape Beds

In landscape beds, a non-selective herbicide containing glyphosate is the best choice for spot treatment of oxalis. Apply glyphosate spray to thoroughly wet the foliage of the weeds. Target oxalis seedlings and young plants (before the flowering stage) for best results. Examples of products containing glyphosate are listed in Table 1. Always read product labels for safe use around landscape ornamentals and established perennials.

Table 1. Examples of Products Containing Glyphosate in Homeowner Sizes.

Active Ingredient Product Name
glyphosate Roundup Original Concentrate
Roundup Pro Herbicide
Martin’s Eraser Systemic Weed & Grass Killer
Quick Kill Grass & Weed Killer
Bonide Kleenup Weed & Grass Killer 41% Super Concentrate
Hi-Yield Super Concentrate
Maxide Super Concentrate 41% Weed & Grass Killer
Super Concentrate Killzall Weed & Grass Killer
Tiger Brand Quick Kill Concentrate
Gordon’s Groundwork Concentrate 50% Super Weed & Grass Killer
Zep Enforcer Weed Defeat III
Eliminator Weed & Grass Killer Super Concentrate
Monterey Remuda Full Strength 41% Glyphosate
Southern States Grass & Weed Killer Concentrate II
Total Kill Pro Weed & Grass Killer Herbicide
Ace Concentrate Weed & Grass Killer

Chemical Control in Lawns

For small numbers of oxalis plants scattered throughout the lawn, a spot treatment with a recommended post-emergent herbicide may provide adequate control. For larger oxalis infestations in the lawn, pre-emergent and post-emergent herbicides may be necessary. Pre-emergent herbicides prevent seed growth, whereas post-emergent herbicides are applied to foliage of the weeds once they emerge. Post-emergent herbicides are often more effective at killing smaller weeds rather than older, mature ones.

Pre-emergent and post-emergent herbicides for oxalis (yellow woodsorrel) control in South Carolina lawns are listed in Tables 2 and 3. Always read the product label for mixing rate for weed control on each turfgrass species and for safe use of the product. Pre-emergent herbicides need to be applied at the proper time of the year, may require one or more subsequent applications, and need to be watered in appropriately. When using a post-emergent herbicide, spray to just wet the foliage of the weeds. For safe use on lawns, spray herbicides when temperatures are below 90 °F. Avoid pesticide drift by spraying on non-windy days. Irrigate the lawn the day before application to reduce drought stress to lawns and to promote active growth of the weed for better herbicide uptake.

Table 2. Pre-emergent Herbicides for Oxalis Control in Home Lawns.

Turfgrass Active Ingredients Examples of Brands & Products
Bahiagrass
Bermudagrass
Centipedegrass
St. Augustinegrass
Zoysiagrass
Tall Fescue
benefin Pennington Crabgrass Preventer
oryzalin Southern Ag Surflan A.S.
benefin + oryzalin XL2G
Green Light Amaze Grass & Weed Preventer
benefin + trifluralin Anderson Turf Products Crabgrass Preventer with 2% Team Herbicide (partial control)
Hi-Yield Crabgrass Control (partial control)
pendimethalin Scotts Halts Crabgrass & Grassy Weed Preventer
dithiopyr Bonide Crabgrass & Weed Preventer for Lawns & Ornamental Beds
Hi Yield Turf & Ornamental Weed & Grass Stopper Containing Dimension
StaGreen CrabEx Crabgrass Preventer
isoxaben Ferti-lome Broadleaf Weed Control with Gallery
prodiamine Helena Pro-Mate Barricade & Fertilizer 0-0-7
Howard Johnson Crabgrass Control with Prodiamine & 0-0-7
Lebanon Pro Fertilizer (0-0-7) with Prodiamine
Lesco Barricade Plus Fertilizer 0-0-7
Lesco Stonewall Plus Fertilizer (0-0-7)
Pro-Mate Barricade Plus Fertilizer (0-0-7)
Scotts Halts Pro 0-0-7 & Halts Pro
Notes: These pre-emergent herbicides should only be applied to well-established turfgrass lawns.
Typically, the optimum time for lawn fertilizer applications and pre-emergent herbicide applications do not coincide. However, the small amount of potash in the 0-0-7 blends is not a problem, & may be useful on sandy soils with fall applications to improve cold weather hardiness of the lawn.

Table 3. Post-emergent Herbicides for Oxalis Control in Home Lawns.

Turfgrass Active Ingredients Examples of Brands & Products Effectiveness
Centipedegrass
St. Augustinegrass
atrazine Hi-Yield Atrazine Weed Killer
Image for St. Augustinegrass & Centipedegrass
with Atrazine
Southern AG Atrazine St. Augustine Weed Killer
Spectracide Weed Stop for Lawns Concentrate for St. Augustine & Centipede Lawns
Fair to Good Control
Bahiagrass
Bermudagrass
Centipedegrass
St. Augustinegrass
Zoysiagrass
Tall Fescue
2, 4-D + dicamba + mecoprop (MCPP) Ferti-lome Weed Out Lawn Weed Killer with
Trimec
Southern Ag Lawn Weed Killer with Trimec
Conc.
Good Control
Bermudagrass1
Zoysiagrass
Centipede
Tall Fescue
sulfentrazone +
quinclorac
Image Kills Crabgrass Concentrate Good Control
Zoysiagrass2
Tall Fescue
triclopyr Ortho Weed B Gon Chickweed, Clover & Oxalis
Killer
Fair to Good Control
Tall Fescue triclopyr Hi-Yield Triclopyr Ester
Monterey Turflon Ester
Fair to Good Control
Bahiagrass
Bermudagrass
Zoysiagrass
Tall Fescue
MCPA + dicamba + triclopyr Monterey Spurge Power Concentrate
Bonide Chickweed, Clover & Oxalis Killer Concentrate
Good Control
1For use on common bermudagrass. Intermediate safety on hybrid bermudagrass.
2Use low rate on zoysiagrass.
Effectiveness Rating:
Poor – P = <70% control
Fair – F = 70-79% control with repeat applications
Good – G = 80-90% control with one application at high rate or repeat application
Excellent – E = >90% control with one application

Oxalis

This diverse genus is comprised of hundreds of species. With so many species available, you can find oxalis in a wide range of annuals, perennials, and even tropical types. Many oxalis are bulb-forming plants while others form vigorous spreading plants that can create dense colonies. Several species of oxalis can also make wonderful, easy to grow houseplants.

genus name
  • Oxalis
light
  • Part Sun,
  • Shade,
  • Sun
plant type
  • Annual,
  • Bulb,
  • Houseplant,
  • Perennial
height
  • Under 6 inches,
  • 6 to 12 inches
width
  • 6 to 12 inches wide
flower color
  • Orange,
  • White,
  • Pink,
  • Yellow
foliage color
  • Blue/Green,
  • Purple/Burgundy,
  • Chartreuse/Gold,
  • Gray/Silver
season features
  • Spring Bloom,
  • Fall Bloom,
  • Summer Bloom,
  • Winter Bloom
problem solvers
  • Groundcover,
  • Drought Tolerant
special features
  • Low Maintenance,
  • Good for Containers
zones
  • 5,
  • 6,
  • 7,
  • 8,
  • 9,
  • 10,
  • 11
propagation
  • Division,
  • Seed,
  • Stem Cuttings

Oxalis Flowers and Foliage

While many species of oxalis have beautiful blossoms, these plants are most commonly grown for their foliage. You can often find them in your local florist’s shop around St. Patrick’s Day as their leaves closely resemble shamrocks and they are often regarded as a sign of luck. These geometric-shape leaves, often triangular in shape, come in shades of purple, burgundy, pink, green, and silvery gray.

The plants bloom with small five-petal blossoms that have intricate details on the inner petals. These blossoms often begin as tubular flowers that twist open to show off dainty stripes and dark-color throats. They can be found in shades of pink and white, while other species feature yellow and orange blossoms. There are even species like Oxalis versicolor that have flowers that resemble peppermint candy: mostly white with an edge of red on the backside that creates a swirled look as the petals twist open.

Oxalis Care

Growing conditions can be quite different between the numerous species in this genus. One of the best bets to find out how to care for your oxalis is to research its origin for information on its natural habitat. Then you can learn its proper growing conditions. Many species of oxalis tend to be alpine plants and therefore need well-drained soil and will not tolerate any amount of standing moisture. These are also typically cool-growing plants and do not care for warm summer weather and may even have a summer dormancy period. Many other species are woodland plants which prefer more shaded garden settings and are generally more tolerant of typical garden conditions. There are also tropical species that are not hardy and are accustomed to warmer climates and will fare better in the summer months.

In general, oxalis are fairly versatile in their sun requirements. Sun exposure varies depending on your species. Many of the bulbous types of oxalis require a period of dormancy. The time of year they become dormant varies from species to species. During this period of dormancy it is important to withhold water to encourage dormancy and prevent the bulbs from rotting. This dormant period is also the best time to divide plants.

Learn how to care for your annuals.

More Varieties of Oxalis

‘Iron Cross’ oxalis

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Oxalis tetraphylla ‘Iron Cross’ offers leaves divided into four leaflets. The center of each is decorated with a purple blotch that looks great against the pink flowers. It grows 10 inches tall and wide. Zones 8-9, though it also thrives as a houseplant.

‘Molten Lava’ oxalis

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This variety produces stunning orange-chartreuse foliage and decorative golden-yellow flowers all spring and summer. It grows 10 inches tall and wide. Zones 9-11, or try it as a houseplant.

‘Purple’ oxalis

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Oxalis regnellii var. triangularis bears rich burgundy-purple foliage and pink-blushed white flowers. It grows 12 inches tall and 8 inches wide. Zones 7-10, though it’s also a good variety to grow indoors.

Redwood sorrel

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This cultivar is native to areas of the Pacific Northwest and bears white or pink flowers in spring and summer over silver-splashed foliage. This groundcover grows 8 inches tall. Zones 7-9

Silver shamrock

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Oxalis adenophylla is an easy-growing groundcover with silvery-blue foliage and pink flowers in late spring. It grows 5 inches tall and 6 inches wide. Zones 6-8

‘Zinfandel’ oxalis

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The ‘Zinfandel’ variety bears rich-purple foliage and golden-yellow flowers all summer long. It grows 10 inches tall and 12 inches wide. Perennial in Zones 9-11; grow as an annual or indoor plant in colder areas.

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