Louisiana’s subtropical humidity creates perfect conditions for dollarweed and Florida betony to spread rapidly. If you’re battling unwanted plants, understanding the **types of lawn weeds in louisiana** is your first step to a healthier yard. These weeds thrive in the state’s warm, wet climate, often outcompeting grass if left unchecked.
This guide breaks down the most common weeds you’ll find in Louisiana lawns. We’ll cover identification, why they grow, and simple control methods. By the end, you’ll know exactly what you’re dealing with and how to fight back.
Types Of Lawn Weeds In Louisiana
Louisiana lawns face a unique mix of broadleaf weeds, grassy weeds, and sedges. Each type requires a different approach for control. Below, we cover the most persistent offenders.
Broadleaf Weeds In Louisiana Lawns
Broadleaf weeds have wide, flat leaves and often showy flowers. They are common in both warm and cool seasons. Here are the top ones to watch for.
Dollarweed (Pennywort)
Dollarweed looks like tiny lily pads with round, scalloped leaves. It loves wet, poorly drained soil. You’ll often see it in low spots or after heavy rain.
- Identification: Shiny, round leaves about the size of a silver dollar. Stems grow from a central point.
- Why it grows: Thrives in consistently moist soil. Overwatering or poor drainage invites it.
- Control: Improve drainage first. Use a post-emergent herbicide with 2,4-D or triclopyr. Hand-pulling works if you get the entire root.
Florida Betony (Rattlesnake Weed)
This weed has square stems and small, white to pink flowers. Its underground tubers look like small rattlesnake rattles. It spreads quickly through lawns.
- Identification: Leaves are opposite, lance-shaped with serrated edges. Tubers are white and crunchy.
- Why it grows: Prefers moist, fertile soil. Often appears in newly sodded lawns.
- Control: Apply a broadleaf herbicide containing dicamba or metsulfuron. Repeat applications may be needed. Pulling by hand is difficult due to deep tubers.
Chickweed
Chickweed is a cool-season annual that forms dense mats. It has small, oval leaves and tiny white flowers. It thrives in the cooler months of fall and spring.
- Identification: Low-growing, spreading stems. Leaves are smooth and pointed.
- Why it grows: Grows in thin, weak lawns. Over-fertilizing with nitrogen can encourage it.
- Control: Use a pre-emergent herbicide in early fall. Post-emergent options include 2,4-D or dicamba. Improve lawn density through overseeding.
Henbit
Henbit is another cool-season annual with purple flowers. It has square stems and scalloped leaves. It often appears in early spring.
- Identification: Leaves are opposite, rounded with deep veins. Flowers are tubular and purple.
- Why it grows: Prefers disturbed soil and thin turf. Common in gardens and lawn edges.
- Control: Mow regularly to prevent seed production. Apply a broadleaf herbicide in late fall or early spring. Hand-pull small patches.
Grassy Weeds In Louisiana
Grassy weeds look like grass but grow faster and coarser. They can quickly overtake a lawn if not managed. Here are the most common ones.
Crabgrass
Crabgrass is a warm-season annual that germinates in late spring. It grows in clumps with wide, light green leaves. It thrives in hot, dry conditions.
- Identification: Stems radiate outward from a central point. Leaves are hairy and have a prominent midrib.
- Why it grows: Grows in thin, stressed lawns. Overwatering or underwatering weakens grass.
- Control: Apply a pre-emergent herbicide in early spring when soil temperatures reach 55°F. Post-emergent options include quinclorac or MSMA (where allowed).
Goosegrass
Goosegrass looks similar to crabgrass but is darker green and grows in tighter clumps. It has a flattened stem base. It tolerates heavy foot traffic and compacted soil.
- Identification: Leaves are folded in the bud. The stem base is white to silver and flattened.
- Why it grows: Common in compacted, high-traffic areas like paths and driveways.
- Control: Aerate compacted soil. Use a pre-emergent in late spring. Post-emergent herbicides like sulfentrazone can help.
Annual Bluegrass (Poa Annua)
Annual bluegrass is a cool-season annual that produces seed heads quickly. It has bright green leaves and a boat-shaped leaf tip. It dies back in summer heat.
- Identification: Fine-textured grass with a distinctive seed head that looks like a panicle. Roots are shallow.
- Why it grows: Thrives in cool, wet weather. Common in overwatered or shaded areas.
- Control: Apply a pre-emergent in late summer or early fall. Reduce watering frequency. Improve drainage.
Dallisgrass
Dallisgrass is a perennial grassy weed with coarse, thick blades. It forms large clumps and produces tall seed heads. It is difficult to control once established.
- Identification: Leaves are wide and rough. Seed heads are finger-like spikes. The base of the plant is often purple.
- Why it grows: Prefers moist, fertile soil. Common in lawns with poor drainage.
- Control: Spot-treat with a non-selective herbicide like glyphosate. Remove clumps by hand. Re-sod or seed the area.
Sedges In Louisiana Lawns
Sedges look like grass but have triangular stems and three-ranked leaves. They thrive in wet, poorly drained soil. They are often mistaken for grass but require different control methods.
Yellow Nutsedge
Yellow nutsedge has bright green leaves and a triangular stem. It produces small, yellow-brown seed heads. It grows faster than lawn grass.
- Identification: Leaves are shiny and V-shaped in cross-section. The stem is solid and triangular. Tubers (nutlets) form underground.
- Why it grows: Thrives in wet, compacted soil. Overwatering encourages it.
- Control: Use a sedge-specific herbicide like halosulfuron or sulfentrazone. Improve drainage. Hand-pulling often leaves tubers behind, causing regrowth.
Purple Nutsedge
Purple nutsedge is similar to yellow nutsedge but has darker green leaves and purple seed heads. It is more aggressive and harder to control.
- Identification: Leaves are darker and wider than yellow nutsedge. Tubers are connected by rhizomes.
- Why it grows: Prefers warm, wet conditions. Common in lawns with poor maintenance.
- Control: Apply a post-emergent herbicide with imazapic or halosulfuron. Multiple applications may be needed. Avoid overwatering.
Kyllinga
Kyllinga is a low-growing sedge that forms dense mats. It has small, round seed heads. It thrives in wet, shaded areas.
- Identification: Leaves are thin and grass-like. Seed heads are small, white to green balls. Stems are triangular.
- Why it grows: Common in poorly drained, shady spots. Often appears near foundations or in low areas.
- Control: Use a sedge herbicide like sulfentrazone. Improve drainage and increase sunlight by trimming trees.
How To Identify Lawn Weeds In Louisiana
Identifying weeds correctly is key to choosing the right control method. Here are simple steps to follow.
- Look at the leaf shape: Broadleaf weeds have wide leaves. Grassy weeds have narrow, parallel-veined leaves. Sedges have triangular stems.
- Check the growth habit: Does it grow in clumps, spread by runners, or form a mat? This helps narrow down the type.
- Note the soil conditions: Is the area wet, dry, shady, or sunny? Weeds often indicate specific problems like poor drainage or compaction.
- Use a weed identification app: Apps like PictureThis or iNaturalist can help. Take a clear photo of the leaf, stem, and flower.
- Compare to online guides: LSU AgCenter has excellent resources for Louisiana-specific weeds. Check their website for photos and descriptions.
Preventing Lawn Weeds In Louisiana
Prevention is easier than cure. A healthy, dense lawn is the best defense against weeds. Here are key strategies.
Mow At The Right Height
Mowing too short stresses grass and invites weeds. For St. Augustinegrass, keep it at 3-4 inches. For Bermuda grass, 1-2 inches works. Never cut more than one-third of the leaf blade at a time.
Water Deeply And Infrequently
Frequent, shallow watering encourages weed seeds to germinate. Water deeply once or twice a week, giving the lawn about 1 inch of water per session. Water early in the morning to reduce evaporation.
Fertilize Properly
Over-fertilizing can feed weeds. Use a slow-release nitrogen fertilizer based on your grass type. Test your soil every 2-3 years to know exactly what nutrients are needed.
Aerate Compacted Soil
Compacted soil prevents grass roots from growing deep. Aerate in spring or fall to improve air and water movement. This also helps reduce sedge and goosegrass.
Apply Pre-Emergent Herbicides
Pre-emergents stop weed seeds from germinating. Apply in early spring for summer weeds like crabgrass. Apply in early fall for winter weeds like chickweed. Follow label instructions carefully.
Controlling Lawn Weeds In Louisiana
When prevention fails, control is necessary. Here are methods for different weed types.
Hand Pulling
For small patches, hand pulling works well. Pull after rain when soil is soft. Make sure to get the entire root or tuber. For sedges, use a weeding tool to remove the nutlets.
Post-Emergent Herbicides
These kill existing weeds. Choose a product labeled for your grass type and weed type. Apply on a calm, dry day when temperatures are below 85°F. Avoid applying before rain.
- Broadleaf weeds: Use 2,4-D, dicamba, or triclopyr.
- Grassy weeds: Use quinclorac, MSMA (where allowed), or fenoxaprop.
- Sedges: Use halosulfuron, sulfentrazone, or imazapic.
Non-Selective Herbicides
For tough weeds like dallisgrass, use glyphosate. Apply carefully to avoid killing desired grass. Spot-treat with a paintbrush or sprayer with a shield.
Cultural Practices
Improve lawn health to outcompete weeds. Overseed thin areas in fall. Use the right grass type for your region. In Louisiana, St. Augustinegrass and Bermuda grass are common choices.
Seasonal Weed Calendar For Louisiana
Weeds appear at different times of the year. Here is a simple calendar to help you plan.
Spring (March-May)
- Pre-emergent for crabgrass and goosegrass (apply when soil reaches 55°F).
- Post-emergent for winter annuals like henbit and chickweed.
- Watch for sedges as soil warms.
Summer (June-August)
- Control sedges and dallisgrass.
- Spot-treat crabgrass and goosegrass.
- Mow high and water deeply.
Fall (September-November)
- Apply pre-emergent for winter weeds like annual bluegrass and chickweed.
- Overseed thin areas.
- Control perennial broadleaf weeds.
Winter (December-February)
- Monitor for winter annuals.
- Hand-pull small patches.
- Plan spring treatments.
Common Mistakes When Dealing With Lawn Weeds
Many homeowners make errors that worsen weed problems. Avoid these common pitfalls.
- Mowing too short: Scalping the lawn weakens grass and exposes soil to weed seeds.
- Overwatering: Frequent light watering encourages weed germination. Water deeply instead.
- Using the wrong herbicide: Applying a broadleaf herbicide on sedges won’t work. Identify the weed first.
- Skipping pre-emergents: Waiting until weeds appear makes control harder. Apply pre-emergents on time.
- Ignoring soil health: Weeds thrive in poor soil. Test and amend your soil regularly.
Frequently Asked Questions
What is the most common weed in Louisiana lawns?
Dollarweed is one of the most common, especially in wet areas. Florida betony and crabgrass are also widespread across the state.
How do I get rid of dollarweed in my Louisiana lawn?
Improve drainage first. Apply a post-emergent herbicide with 2,4-D or triclopyr. Hand-pulling works if you remove the entire root system.
Can I use vinegar to kill lawn weeds in Louisiana?
Vinegar can kill small weeds but often damages grass too. It is not selective and may not kill roots. Commercial herbicides are more effective for persistent weeds.
When should I apply pre-emergent for weeds in Louisiana?
Apply in early spring when soil temperatures reach 55°F (usually late February to March). For winter weeds, apply in early fall (September to October).
What grass type is best for preventing weeds in Louisiana?
St. Augustinegrass is popular for its dense growth that shades out weeds. Bermuda grass is also effective but requires more maintenance. Choose a grass suited to your sun and soil conditions.
Understanding the types of lawn weeds in louisiana gives you a real advantage. With the right identification, prevention, and control methods, you can maintain a healthy, weed-free lawn. Start by assessing your yard, improving soil health, and applying treatments at the right time. Your lawn will thank you.