Weeds can be a nuisance to even the most seasoned gardener, and there are many varieties and species that wreak havoc on Oklahoma lawns.
Weed growth can indicate several things about your lawn’s overall health and can be nearly impossible to eradicate by manual means.
The professionals at Willis Lawn Services can help by identifying the weed species, diagnosing the best solution for each species, and taking action to fight the issue so you can have a beautiful lawn.
Identifying Common Weeds and How to Fight Them
Keeping a healthy lawn is the best defense against Oklahoma weeds. Proper mowing, irrigation, aeration, and fertilization of turfgrass can go a long way in keeping your lawn free of weeds.
However, there are instances where you may need to resort to chemical means. It is always best to use a professional when introducing new herbicides to your yard.
Here are some of the common weeds found in Oklahoma and the best ways to fight them:
1. American Aster
Characteristics: American aster, also known as bushy aster, is a native wildflower that many people select for their gardens. However, when this plant is fully grown and no longer flowering, they can be unattractive and weedlike on your lawn.
Aster produces plentiful small, ray-like flowers ranging from purple to lavender to white. It has long stalks that grow upright or along the ground. The leaves are plentiful and soft with spearlike tips.
How to fight: Bushy aster likes to grow on unhealthy, dry soils. Hand-pulling aster is the most effective way of getting them out of your lawn.
However, if there are too many, you can try using corn gluten meal as a pre-emergent or try a broadleaf weed killer. When using these products it is best to utilize them during the late fall before seeds have germinated.
2. Annual Bluegrass
Characteristics: Annual bluegrass grows in clumps, producing greenish-white seed heads. It has smooth, green leaves growing in clusters throughout the spring.
How to fight: Annual bluegrass can be dug up easily, especially when the soil is moist.
If there are too many clumps and you decide to use a herbicide, it’s a good idea to do treatments in the fall before the seeds germinate. When seed heads become visible, be sure to use a bag attachment on your mower to collect the seeds and inhibit them from spreading more.
3. Black Medic
Characteristics: Black medic has small, yellow flowers appearing in ball-shaped clusters. It has oval-shaped leaves which grow in groups of three. The weeds spread low and are often found alongside other weeds such as white clover.
How to fight: Black medic thrives in compacted soil. The presence of this weed in your lawn can indicate your soil has low nitrogen content.
Before using a herbicide, you can try hand-pulling individual plants. Aerating your lawn and adding nutrients to your soil can help fight this weed. If your lawn is highly infested, you can try using a broadleaf herbicide.
4. Bull Nettle
Characteristics: Bull nettle, also known as stinging nettle, has long, stiff, hollow hairs that irritate and sting the skin. Leaves are obovate, or egg-shaped, with jagged edges. The leaves have a smooth surface on the top and prickly hairs on the underside.
Greenish-white flowers appear between May and October on slender spikes that form along with the shoots where the leaves develop.
How to fight: Bull nettle doesn’t compete well with grass. A healthy lawn will do well to keep it at bay.
Preventing a patchy lawn by properly watering, fertilizing, and mowing should keep this weed away. If you find this weed, digging it up or hand-pulling can be effective. Be sure to wear gloves to avoid its stinging hairs.
5. Carolina Geranium
Characteristics: Carolina geranium is a spreading annual or biennial, growing about 1 foot tall. Its green, lobed leaves extend from long stems, usually pink to red in color.
It is also sometimes called cranesbill due to its beak-like fruit. The flowers of this weed have five petals, usually white to lavender in color.
How to fight: Proper lawn management will help your lawn compete against this weed and should be done before trying a herbicide. But if it is necessary a post-emergent herbicide with 2,4-D or metsulfuron works well against Carolina geranium.
6. Carpet Grass
Characteristics: Carpet grass is pale green to yellowish-green grass. It is a warm-season grass. It spreads in a mat-like manner and has tall, Y-shaped seed heads throughout the growing season, making it look weedlike and in constant need of mowing.
It can be used as a turfgrass, but its pale color, sporadic growth habit, and unattractive seed heads make it a difficult and unpopular choice.
How to fight: If carpet grass has taken over your lawn it is most likely due to the moisture of your soil. Carpet grass likes to grow in moist soils with bad drainage that are too boggy for other grasses like Bermuda.
A post-emergent herbicide in water-dispersible granules can be successful in fighting carpet grass. After getting rid of the weed, it is important to put in a replacement grass species immediately so that the desired grass can take residence and prevent carpet grass from returning.
Characteristics: Carpetweed is a low, sprawling, annual weed that spreads from a central taproot. This weed has smooth stems and leaves with white flowers that bud from the leaf stalk.
How to fight: This weed thrives in sunny, loose soils. Hand pulling carpetweed or adjusting your mowing height can be adequate solutions. However, if the weed is plentiful, pre-emergent or post-emergent herbicides can be used with caution.
Characteristics: Chickweed can vary in growth, sometimes appearing erect and sometimes creeping along the ground. It has forked stems and hairs that border its leaves.
Chickweed flowers have five deeply cut petals, sometimes mistaken for 10.
How to fight: Chickweed has shallow roots that can easily be pulled manually without the use of herbicides. It can be more difficult to pull when the weed is intermixed with turfgrass.
When this is the case, use a trowel to dig up the roots. Exposing the soil can allow oxygen to penetrate it, which will discourage the growth of the weed.
Afterward, spread a combination of fertilizer and weed killer and water the area. This approach will help the grass to take over and push any leftover weeds out. Having your lawn aerated once or twice a year can help prevent weeds like chickweed.
9. Crab Grass
Characteristics: Crabgrass is a green, grass-like weed that grows in thick clumps with sprawling stems. The blades of crabgrass can be thick and coarse. Its flowering stems branch and emerge apart at the edge of the stem in intervals.
How to fight: Manual removal of crabgrass when the weed is young can be effective. It is important to try and remove crabgrass before it seeds, as the seeds can live for years.
Mowing your lawn to the correct height, watering properly, and fertilizing correctly can help your turfgrass and reduce crabgrass germination. The use of pre-emergent herbicides can be successful if used before the crabgrass germinates.
10. Creeping Jenny
Characteristics: Creeping jenny is a prolific weed with an extensive root system. This weed’s flowers are trumpet-shaped and white to light purple in color.
Creeping jenny produces vines that creep along the ground and climb and curl around nearby structures.
How to fight: Manual removal of creeping jenny before it flowers and seeds can reduce the spread. Unfortunately, manual removal may not get rid of this weed because its roots can extend several feet underground and its seeds can live for years.
Cutting off the top of the plant and hoeing the area where the plant grows in combination with herbicides can hinder the spread.
Characteristics: Cudweed is known for its silky white foliage. Mature plants are tall and sparsely branched. The flowers are crowded with a yellowish head before full bloom. Once bloomed the flowers look tannish-white.
How to fight: Keeping a healthy lawn with no bare spots can fight cudweed colonization. A broadleaf herbicide can also be used to eradicate the weed.
12. Curly Dock
Characteristics: Curly dock is a broadleaf weed. It has thick, unbranched stem bolts with usually a reddish tint. It can reach a height of about 5 feet. The flowers form long clusters branching from the stem.
How to fight: Curly dock is a hardy weed that can withstand significant variations in soil moisture. It can be difficult to eradicate. The taproots go deep and the seeds can live for years.
Cutting it down regularly while mowing can help weaken the weed. You could also try digging up the taproot. Broadleaf herbicides can be used to kill curly dock.
Characteristics: Dallisgrass is a coarse perennial growing in thick, circular, green clumps with sprawling stems.
How to fight: An integrated lawn care method is the best way to prevent dallisgrass. Raking and dethatching your lawn, aerating annually, watering deeply, and mowing high can help prevent dallisgrass from growing.
Per-emergent and post-emergent herbicides can also be used against this pesky grass. It usually takes two spot applications.
Characteristics: The dandelion is known for having a single yellow flower composed of small ray flowers. It has a single stem with milky sap. The bottom leaves are broad and jagged.
How to fight: Dandelions can be tough to get rid of due to their long taproot. One method is to dig the plants up and fill the hole with a pre-emergent herbicide. You can also use a broadleaf herbicide.
15. Evening Primrose
Characteristics: When blooming, evening primrose has large flowers with four petals each, ranging in color. Their stems are usually red.
It can grow tall or creep along the ground. Some variations have toothed leaves while others are lobed. The flowers open in the evening and close in the morning.
How to fight: Proper mowing, watering, and fertilization are your best defense against this weed. A selective broadleaf weed killer like 2,4-D or dicamba blended with glyphosate can be used in early spring to fight evening primrose.
Characteristics: Henbit is an annual low-growing herbaceous weed with green to purple square stems.
The upper leaves are directly attached to the stems while the lower leaves have small stocks that attach the leaf to the stem. Its flowers are small and reddish-purple in color.
How to fight: Maintaining a thick turfgrass is the best way to control the spread of henbit. It has shallow roots, making it easy to pull. However, it can overtake a lawn quickly and it may be easier to use a broadleaf weed killer on large colonies.
Characteristics: Johnsongrass is a large, coarse, green bunchgrass. It can grow up to 6 feet tall with loose branching clusters of flowers. Seeds are yellow to purple, occurring in large, spreading seed clusters.
How to fight: Regular mowing can help deplete Johnsongrass of nutrients over time.
Chemical control is usually the most effective way to eliminate Johnsongrass. The use of selective herbicides in the fall can help fight it.
Characteristics: Knotweed is a tough, shrub-like plant that grows in large, dense clumps that can grow up to 9 feet tall. The flowers are small, greenish-white clusters.
How to fight: Cutting back the plant can be a temporary solution. To truly exterminate knotweed, you may need to use a combination of cutting and herbicides.
Herbicides with the active ingredient glyphosate can help fight this weed. One to two applications a year may be needed.
Characteristics: Lambsquarters is an upright plant that can grow up to several feet tall. The leaves are arrowhead-shaped, usually with a dusty white coating. They have clusters of small yellow-green flowers.
How to fight: It is important to pull lambsquarters before it flowers and seeds because it can produce thousands of seeds. After you manually pull the weed, you can also try sprinkling a pre-emergent herbicide at the base where the root was.
Characteristics: Nutgrass is a sedge that has lean rootstocks producing small, edible tubers that look like nuts.
It grows faster than turfgrass and usually spikes above our lawns in a light green, V-shaped stem. If left to its own devices, it can form clusters in your yard.
How to fight: Mowing high and keeping your turfgrass tall can help crowd out this weed. You can also try a selective herbicide that targets nutsedge.
Characteristics: Parsley-piert is a branching winter annual that can grow about 1 to 3 inches tall. It looks similar to the popular herb parsley.
The leaves are directly attached to the stem but can also be petiole with cone-shaped, toothed portions at the bottom that surrounds the stem.
How to fight: Parsley-piert likes cool climates and will grow in thin and shaded spots of your lawn.
Selecting turfgrass that will grow in shaded areas and compete for the available space can help control this weed.
Characteristics: Pigweed is a tall, erect plant with dense clusters consisting of many small, greenish flowers.
How to fight: Manually pulling out this weed is usually successful. Pigweed seedlings are very delicate and can be killed easily by disturbances. Mowing your lawn and keeping it healthy is a good way to fight this weed.
Characteristics: A plantain is a broadleaf weed with greenish flowers that spike up from a central flat rosette. The leaves are oval-shaped. The blooms are hard to distinguish from the buds and run along a long stalk.
How to fight: Pulling up or digging out plantain weeds can be a successful way to fight it. Watering the root area of the plant before you attempt to pull it can make it easier to get the entire root out.
If any root is left, the plant can return. Aerating your lawn and keeping it lush with no bare spots can help keep this weed away.
24. Prickly Lettuce
Characteristics: Mature prickly lettuce grows upright up to 6 1/2 feet tall. It can exude a milky sap when cut. It has prickly hairs along the central vein on the underside of the leaves.
The central stem also grows sharp hairs and can be green to red in color. The stems branch at the flower head and can be bristly or smooth. The flowers are a pale yellow and extend outward on the branches.
How to fight: Pulling small infestations can be successful. Make sure you get the entire taproot or it will return.
If herbicide is needed because you are unable to pull or dig up the roots, then it is best if used in the fall and spring during the active growing season.
Nonselective herbicides with glyphosate, glufosinate, or paraquat can be used.
Characteristics: Purslane spreads in a mat-like structure. This weed can sometimes be mistaken for a succulent.
The stems are usually reddish-purple, thick, and waxy. The leaves are shiny and green. It has bright yellow flowers that open in the morning sun and close after a few hours.
How to fight: It is best to fight purslane when the plant is still young, before it flowers and spreads its seeds.
Purslane has shallow roots and can easily be pulled. Its seeds need light to germinate. The best way to keep it from coming back is to get rid of patchy areas in your lawn.
Characteristics: Ragweed is an annual with coarse, hairy stems. The leaves are also hairy with a feathery appearance. The yellow-greenish flowers grow in long clusters.
How to fight: A successful method to fight ragweed in your lawn is to mow consistently because it does not tolerate being mowed well. Ragweed likes poor soil, so adding nutrients to your soil will also help.
27. Shepherd’s Purse
Characteristics: Shepherd’s purse has a wide rosette of low leaves with one or more tall branching stalks developing at the center. Flowers are white and short-lived.
It is known for its heart-shaped, green fruit found along the flower stock.
How to fight: The best way to control shepherd’s purse is by pulling it manually. If a herbicide is needed, you can use a post-emergent labeled for use against shepherd’s purse.
28. Spiny Sowthistle
Characteristics: Spiny sowthistle has very prickly leaves that initially grow as a rosette on the ground. It can grow several feet tall and exudes a milky sap when injured.
The leaves are egg-shaped and lined with spiny margins. The stems are unbranched and erect, usually light purple in color. The flowers are yellow clusters that look a lot like a dandelion bloom.
How to fight: In the spring, dig up thistle with a shovel before it flowers. Annual sowthistle has a single taproot, which is easier to pull out than a perennial sowthistle that has horizontal root systems. Herbicides with glyphosate may be required.
Spiny sowthistle can be a skin irritant, so make sure to wear gloves and long sleeves when handling.
Characteristics: Spurge is a dark green plant with red stems that grows low to the ground in a mat-like fashion. It has white flowers and small, oval-shaped leaves with a red spot in the center. It exudes milky white sap when cut.
How to fight: Pulling can be a good method of getting rid of spurge, but be sure to get the entire taproot and make sure the plant does not break off at the stem or it will return.
You can also use a selective herbicide with spurge listed on the label if absolutely necessary. Fertilizing your lawn, mowing high, and watering deeply can help fight this weed’s return.
30. Vetch (Narrow-leaf)
Characteristics: Vetch has branching tendrils that form large trailing mats. Leaves are narrow and compound. It has long stems with no leaves that bloom purple flowers.
How to fight: Unfortunately, the most successful way to fight vetch is through chemical means. Early fall is the best time to spray vetch. Gather the tendril-like branches up in a bunch as best as you can and spray with herbicide.
31. White Clover
Characteristics: White clover usually grows close to the ground, forming mats. The leaves are compound with three alternating egg-shaped leaflets, which are smooth with a small notch at the tip and usually a white, V-shaped marking.
The flowers are globe-shaped with a white to purple color.
How to fight: White clover can be hand-pulled. The weed grows in clumps and it can be easy to remove manually. Just be sure to get the roots.
Broadleaf herbicides applied in the fall can help fight this weed. If used in the spring, the weed can usually reemerge.
32. Wood Sorrel
Characteristics: Often mistaken for clover, wood sorrel is distinguished by the three, heart-shaped leaflets found on top of each long stalk. It has bright yellow flowers with five petals.
How to fight: Wood sorrel can be pulled by hand. Try to pull the weed before it flowers to prevent seeds from spreading. A post-emergent herbicide can be used to fight seeds that have already escaped.
Characteristics: Yarrow is a low-growing plant that generates flower shoots four times taller than its foliage height. It grows dome-shaped clusters of small white flowers with yellow pistils in the center.
How to fight: Digging out spots where yarrow has spread to a depth of 12 inches can help remove several of the rhizomes, but chlorsulfuron, clopyralid, dicamba, MCPA, triclopyr, and 2,4D are useful tools against yarrow.
Finding Help for Your Weed Problem
While many weeds have their uses as food or medicine, some can be noxious and invasive. Here in Oklahoma weeds are mostly viewed as an unsightly nuisance.
Dealing with herbicides can be scary and complicated. Using a professional lawn service like Willis Lawn Services can eliminate the worry and hassle of choosing and dealing with hazardous herbicides yourself.
Willis Lawn Services has experts who can keep your lawn healthy, which reduces the available space for weed invasion, and choose the safest and most effective products for your yard.