Weeds with purple under leaves are among the most distinctive and easily recognizable invasive plants in gardens, lawns, and natural areas. These unique weeds feature striking purple or reddish-purple coloration on the undersides of their leaves, making them stand out from surrounding vegetation. Proper identification and timely control measures are essential for managing these persistent invaders.

The purple coloration on the undersides of leaves is caused by pigments called anthocyanins, which serve various functions including protection from UV radiation, defense against herbivores, and adaptation to environmental stress. Many weeds with purple leaf undersides are particularly aggressive because their pigmentation helps them thrive in conditions where green plants struggle, including low-light environments and nutrient-poor soils.

Effective management of weeds with purple under leaves requires understanding the specific growth habits, spread mechanisms, and vulnerabilities of each species. Different weeds respond to different control methods—some require targeted herbicide applications, others need physical removal, and many require persistent, integrated strategies that combine multiple approaches over several growing seasons.

This comprehensive guide examines 30 weeds with purple under leaves, providing reliable identification characteristics, details on their growth patterns, and expert recommendations for managing these persistent and distinctive landscape invaders. With the right approach, you can effectively control these colorful weeds and protect your property from their spread.

30 Weeds With Purple Under Leaves

1. Purple Deadnettle (Lamium purpureum) – Purple-Undersided Spring Weed

Purple deadnettle is one of the most common and recognizable weeds with purple undersides on its leaves. This winter annual weed has square stems, opposite leaves with purple coloring on both the upper and lower surfaces, and clusters of small purple flowers. The plant forms dense patches that can overtake lawns and gardens in early spring.

Key identification features: Square stems; opposite, heart-shaped leaves with purple coloring on upper and lower surfaces; clusters of small purple flowers; low-growing habit reaching 4-12 inches. The leaves become more purple as the plant matures, with the undersides being particularly colorful.

Purple deadnettle thrives in moist, disturbed areas and is most common in spring. The plant completes its lifecycle before many other weeds emerge. It produces numerous seeds that remain viable in soil. Control is achieved through early spring herbicide applications or manual removal before flowering. Broadleaf herbicides containing 2,4-D or dicamba are effective.

Pros:

• Easy to identify
• Annual lifecycle
• Responds to herbicides

Cons:

• Spreads rapidly
• Early spring emergence
• Prolific seed production

2. Henbit (Lamium amplexicaule) – Purple-Undersided Winter Annual

Henbit is a winter annual weed with purple-tinged leaves and square stems, closely related to purple deadnettle. This plant invades lawns, gardens, and disturbed areas, forming dense patches in early spring. The leaves have a distinctive purple coloration on the undersides and pinkish-purple flowers.

Key identification features: Square stems; opposite, rounded leaves with purple coloring on undersides; clasping leaves that wrap around the stem; pinkish-purple flowers; low-growing habit reaching 6-12 inches. The leaves are deeply veined and often have a purple tinge underneath.

Henbit thrives in disturbed areas and completes its lifecycle in winter and early spring. The plant produces numerous seeds that remain viable in soil for many years. Broadleaf herbicides containing 2,4-D or dicamba provide effective control. Maintaining thick, healthy turf prevents establishment.

Pros:

• Easy to identify
• Winter annual lifecycle
• Responds to herbicides

Cons:

• Early spring emergence
• Prolific seed production
• Can be persistent

3. Purpleleaf Plantain (Plantago lanceolata) – Purple-Undersided Broadleaf Weed

Purpleleaf plantain is a common lawn weed with narrow, lance-shaped leaves that have a distinctive purple base and purple undersides. This perennial weed forms rosettes in lawns and disturbed areas. The purple coloration on the leaf undersides makes it easily identifiable.

Key identification features: Lance-shaped leaves with purple undersides; prominent parallel veins; rosette growth habit; deep taproot; tall flower spikes. The plant produces numerous seeds that remain viable in soil.

Broadleaf herbicides containing 2,4-D or dicamba provide control. Manual removal requires digging out the entire taproot. Maintaining thick, healthy turf prevents establishment. Improving soil conditions helps reduce populations.

Pros:

• Easy to identify
• Responds to herbicides
• Can be controlled with persistence

Cons:

• Deep taproot
• Prolific seed production
• Persistent growth

4. Purpleleaf Sorrel (Oxalis violacea) – Purple-Undersided Shamrock Weed

Purpleleaf sorrel is a low-growing weed with purple undersides on its leaves and small pink or white flowers. This plant forms patches in lawns, gardens, and disturbed areas. The leaves are divided into three heart-shaped leaflets that fold up at night, with distinctive purple coloring underneath.

Key identification features: Trifoliate leaves with purple undersides; heart-shaped leaflets that fold at night; small pink or white flowers; low-growing habit. The plant spreads through seeds and small bulbils.

Broadleaf herbicides containing 2,4-D or dicamba provide control. Maintaining thick, healthy turf prevents establishment. Manual removal is difficult due to the bulbils that can regenerate.

Pros:

• Attractive appearance
• Can be controlled with herbicides
• Some species are edible

Cons:

• Spreads through bulbils and seeds
• Can be persistent
• Difficult to remove manually

5. Purpleleaf Persicaria (Persicaria spp.) – Purple-Undersided Smartweed

Purpleleaf persicaria is an annual weed with purple-tinged leaves and small pink or white flowers. This plant invades moist areas, gardens, and disturbed sites. The leaves have a distinctive purple blotch in the center and purple coloring on the undersides.

Key identification features: Lance-shaped leaves with purple blotch and purple undersides; pink or white flowers in spikes; erect growth reaching 1-3 feet; annual lifecycle. The plant thrives in moist, disturbed areas.

Broadleaf herbicides containing 2,4-D or dicamba provide control. Improving drainage helps prevent establishment. Manual removal is effective for small infestations.

Pros:

• Annual lifecycle
• Responds to herbicides
• Drainage improvement helps

Cons:

• Thrives in moist conditions
• Prolific seed production
• Can be persistent

6. Purpleleaf Beggarticks (Bidens frondosa) – Purple-Undersided Burr Weed

Purpleleaf beggarticks is an annual weed with purple-tinged leaves and sticky seeds that cling to clothing and fur. This plant invades disturbed areas, gardens, and moist sites. The leaves have a distinctive purple or reddish tint on the undersides.

Key identification features: Opposite leaves with purple undersides; small yellow flowers; sticky, barbed seeds; erect growth reaching 1-3 feet. The seeds are easily dispersed by animals and humans.

Broadleaf herbicides containing 2,4-D or dicamba provide control. Mowing prevents seed production. Manual removal is effective for small infestations.

Pros:

• Annual lifecycle
• Responds to herbicides
• Manual removal possible

Cons:

• Sticky seeds
• Prolific seed production
• Can be persistent

7. Purpleleaf Groundsel (Senecio spp.) – Purple-Undersided Winter Annual

Purpleleaf groundsel is a winter annual weed with purple-tinged leaves and yellow flowers. This plant invades gardens, lawns, and disturbed areas. The leaves have a distinctive purple or reddish tint on the undersides.

Key identification features: Yellow flowers; deeply lobed leaves with purple undersides; upright growth; winter annual lifecycle. The plant produces numerous wind-dispersed seeds.

Broadleaf herbicides containing 2,4-D or dicamba provide control. Manual removal is effective for small infestations before seed set. Maintaining dense vegetation helps prevent establishment.

Pros:

• Annual lifecycle
• Responds to herbicides
• Manual removal possible

Cons:

• Prolific seed production
• Wind-dispersed seeds
• Can be persistent

8. Purpleleaf Speedwell (Veronica spp.) – Purple-Undersided Creeping Weed

Purpleleaf speedwell is a low-growing perennial weed with purple-tinged leaves and blue or white flowers. This creeping plant forms dense mats that can overtake lawns and gardens. The leaves have a distinctive purple or reddish tint on the undersides.

Key identification features: Small blue or white flowers; opposite, small leaves with purple undersides; creeping stems that root at nodes; low-growing habit. The plant spreads through seeds and creeping stems.

Broadleaf herbicides containing dicamba or triclopyr provide control. Improving lawn density through proper cultural practices helps prevent establishment. Manual removal is effective for small infestations.

Pros:

• Attractive flowers
• Can be controlled with herbicides
• Indicates turf issues

Cons:

• Creeping spread
• Persistent growth
• Can be invasive

9. Purpleleaf Chickweed (Stellaria spp.) – Purple-Undersided Winter Annual

Purpleleaf chickweed is a low-growing winter annual weed with purple-tinged leaves and small white flowers. This plant forms dense mats in lawns and gardens. The leaves have a distinctive purple or reddish tint on the undersides, especially in cold weather.

Key identification features: Small white, star-shaped flowers; oval, pointed leaves with purple undersides; green stems with a line of hairs; low-growing habit. The plant produces numerous seeds that remain viable in soil.

Broadleaf herbicides containing dicamba or triclopyr provide control. Maintaining thick, healthy turf prevents establishment. Manual removal is effective for small infestations.

Pros:

• Annual lifecycle
• Responds to herbicides
• Manual removal possible

Cons:

• Prolific seed production
• Can be persistent
• Early spring emergence

10. Purpleleaf Spurge (Euphorbia spp.) – Purple-Undersided Prostrate Weed

Purpleleaf spurge is a prostrate annual weed with purple-tinged leaves and milky sap. This plant forms dense mats in lawns, gardens, and disturbed areas. The leaves have a distinctive purple or reddish tint on the undersides, often with a dark spot in the center.

Key identification features: Prostrate growth habit; oval leaves with purple undersides and dark spot; milky sap; small, inconspicuous flowers. The plant produces numerous seeds that remain viable in soil.

Broadleaf herbicides containing 2,4-D or dicamba provide control. Maintaining thick, healthy turf prevents establishment. Manual removal is effective for small infestations.

Pros:

• Annual lifecycle
• Responds to herbicides
• Manual removal possible

Cons:

• Milky sap can irritate skin
• Prolific seed production
• Can be persistent

11. Purpleleaf Mallow (Malva spp.) – Purple-Undersided Broadleaf Weed

Purpleleaf mallow is a low-growing weed with purple-tinged leaves and pink or white flowers. This plant invades lawns, gardens, and disturbed areas. The leaves are round to kidney-shaped with a purple or reddish tint on the undersides.

Key identification features: Round to kidney-shaped leaves with purple undersides; pink or white flowers; low-growing, creeping habit; annual or biennial lifecycle. The plant produces numerous seeds that remain viable in soil.

Broadleaf herbicides containing 2,4-D or dicamba provide control. Manual removal is effective before seed production. Improving soil conditions helps prevent establishment.

Pros:

• Annual or biennial lifecycle
• Can be controlled with herbicides
• Manual removal possible

Cons:

• Prolific seed production
• Can be persistent
• Seeds remain viable for years

12. Purpleleaf Nightshade (Solanum spp.) – Purple-Undersided Toxic Weed

Purpleleaf nightshade is a toxic weed with purple-tinged leaves and purple or white flowers. This plant invades gardens, fields, and disturbed areas. The leaves have a distinctive purple or reddish tint on the undersides, and the berries are toxic.

Key identification features: Purple or white flowers; alternate, lobed leaves with purple undersides; purple or black berries; erect or spreading growth. The plant produces numerous seeds that remain viable in soil.

Systemic herbicides containing glyphosate or 2,4-D provide control. Physical removal requires protective gloves. Preventing seed production is essential.

Pros:

• Systemic herbicide effective
• Manual removal possible
• Can be controlled with persistence

Cons:

• Highly toxic
• Prolific seed production
• Can be persistent

13. Purpleleaf Pigweed (Amaranthus spp.) – Purple-Undersided Summer Annual

Purpleleaf pigweed is a summer annual weed with purple-tinged leaves and green flower spikes. This aggressive weed invades gardens, crop fields, and disturbed areas. The leaves have a distinctive purple or reddish tint on the undersides.

Key identification features: Oval leaves with purple undersides; dense green flower spikes; erect, branching stems; rapid growth reaching 3-6 feet. The plant produces thousands of seeds per plant.

Systemic herbicides containing glyphosate or 2,4-D provide effective control. Cultivation before seed set prevents spread. Manual removal is effective for small infestations.

Pros:

• Can be controlled with herbicides
• Annual lifecycle
• Manual removal possible

Cons:

• Prolific seed production
• Seeds remain viable for decades
• Can be persistent

14. Purpleleaf Dock (Rumex spp.) – Purple-Undersided Taproot Weed

Purpleleaf dock is a perennial weed with purple-tinged leaves and a deep taproot. This plant invades gardens, pastures, and disturbed areas. The leaves have a distinctive purple or reddish tint on the undersides, especially at the base.

Key identification features: Long, wavy-edged leaves with purple undersides; deep taproot; tall flower spikes; perennial lifecycle. The plant produces numerous seeds that remain viable in soil.

Systemic herbicides containing 2,4-D or dicamba provide control. Manual removal requires digging out the entire taproot. Preventing seed production is essential.

Pros:

• Systemic herbicide effective
• Manual removal possible
• Can be controlled with persistence

Cons:

• Deep taproot
• Prolific seed production
• Seeds remain viable for years

15. Purpleleaf Thistle (Cirsium spp.) – Purple-Undersided Spiny Weed

Purpleleaf thistle is a biennial or perennial weed with purple-tinged, spiny leaves and purple flower heads. This aggressive thistle invades pastures, roadsides, and disturbed areas. The leaves have a distinctive purple or reddish tint on the undersides.

Key identification features: Purple flower heads; spiny, lobed leaves with purple undersides; spiny stems; biennial or perennial lifecycle. The plant produces numerous wind-dispersed seeds.

Systemic herbicides containing glyphosate or clopyralid provide control. Mowing before flowering prevents seed production. Biological control using thistle-feeding insects can provide suppression.

Pros:

• Systemic herbicides effective
• Biological control options
• Mowing prevents seed

Cons:

• Extremely prickly
• Deep taproot
• Prolific seed production

16. Purpleleaf Sowthistle (Sonchus spp.) – Purple-Undersided Dandelion Lookalike

Purpleleaf sowthistle is an annual weed with purple-tinged leaves and yellow flowers. This plant invades gardens, lawns, and disturbed areas. The leaves have a distinctive purple or reddish tint on the undersides.

Key identification features: Yellow, dandelion-like flowers; lobed leaves with purple undersides; hollow stems; milky sap. The plant produces numerous wind-dispersed seeds.

Systemic herbicides containing glyphosate or 2,4-D provide control. Regular mowing prevents flowering and seed production. Manual removal is effective for small infestations.

Pros:

• Systemic herbicide effective
• Annual lifecycle
• Cultural control works

Cons:

• Prolific seed production
• Wind-dispersed seeds
• Can be persistent

17. Purpleleaf Lettuce (Lactuca spp.) – Purple-Undersided Tall Weed

Purpleleaf lettuce is a tall annual or biennial weed with purple-tinged leaves and yellow flowers. This plant invades gardens, roadsides, and disturbed areas. The leaves have a distinctive purple or reddish tint on the undersides.

Key identification features: Yellow flower heads; prickly or smooth leaves with purple undersides; tall, erect stems; milky sap. The plant produces numerous wind-dispersed seeds.

Systemic herbicides containing glyphosate or 2,4-D provide control. Regular mowing prevents flowering and seed production. Manual removal requires removing the entire taproot.

Pros:

• Systemic herbicide effective
• Cultural control works
• Mowing prevents seed

Cons:

• Prickly leaves and stems
• Deep taproot
• Prolific seed production

18. Purpleleaf Hawkweed (Hieracium spp.) – Purple-Undersided Yellow-Flowered Weed

Purpleleaf hawkweed is a perennial weed with purple-tinged leaves and yellow flowers. This invasive weed forms dense patches in pastures, lawns, and disturbed areas. The leaves have a distinctive purple or reddish tint on the undersides.

Key identification features: Yellow flowers; hairy, basal leaves with purple undersides; erect flower stalks; stoloniferous growth. The plant spreads through seeds and stolons.

Systemic herbicides containing 2,4-D or dicamba provide control. Mowing before flowering prevents seed production. Maintaining dense vegetation helps prevent establishment.

Pros:

• Systemic herbicide effective
• Mowing prevents seed
• Cultural control works

Cons:

• Stoloniferous spread
• Prolific seed production
• Persistent growth

19. Purpleleaf Mullein (Verbascum spp.) – Purple-Undersided Woolly Weed

Purpleleaf mullein is a biennial weed with purple-tinged, woolly leaves and yellow flowers. This plant invades disturbed areas, roadsides, and dry soils. The leaves have a distinctive purple or reddish tint on the undersides and are covered with soft hairs.

Key identification features: Woolly, silvery leaves with purple undersides; tall flower spikes; yellow flowers; biennial lifecycle. The plant produces numerous seeds that remain viable in soil.

Systemic herbicides containing 2,4-D or dicamba provide control. Manual removal is effective for small infestations. Preventing seed production is essential.

Pros:

• Systemic herbicide effective
• Manual removal possible
• Biennial lifecycle

Cons:

• Prolific seed production
• Seeds remain viable for years
• Can be persistent

20. Purpleleaf Verbena (Verbena spp.) – Purple-Undersided Creeping Weed

Purpleleaf verbena is a creeping perennial weed with purple-tinged leaves and purple flowers. This plant forms dense mats in lawns, gardens, and disturbed areas. The leaves have a distinctive purple or reddish tint on the undersides.

Key identification features: Purple flowers; opposite, toothed leaves with purple undersides; creeping stems that root at nodes; low-growing, mat-forming habit. The plant spreads through seeds and creeping stems.

Broadleaf herbicides containing 2,4-D or dicamba provide control. Maintaining thick, healthy turf prevents establishment. Manual removal is effective for small infestations.

Pros:

• Attractive flowers
• Can be controlled with herbicides
• Indicates turf issues

Cons:

• Creeping spread
• Persistent growth
• Can be invasive

21. Purpleleaf Groundcherry (Physalis spp.) – Purple-Undersided Fruit Weed

Purpleleaf groundcherry is an annual or perennial weed with purple-tinged leaves and distinctive papery fruit husks. This plant invades gardens, disturbed areas, and roadsides. The leaves have a distinctive purple or reddish tint on the undersides.

Key identification features: Yellow flowers; alternate leaves with purple undersides; papery fruit husks; erect or sprawling growth. The plant produces numerous seeds that remain viable in soil.

Systemic herbicides containing glyphosate or 2,4-D provide control. Manual removal is effective for small infestations. Preventing seed production is essential.

Pros:

• Systemic herbicide effective
• Manual removal possible
• Can be controlled with persistence

Cons:

• Prolific seed production
• Can be persistent
• Sprawling growth habit

22. Purpleleaf Brome (Bromus spp.) – Purple-Undersided Grass Weed

Purpleleaf brome is an annual or perennial grass weed with purple-tinged leaves and seed heads. This plant invades disturbed areas, pastures, and roadsides. The leaves have a distinctive purple or reddish tint on the undersides.

Key identification features: Grass-like leaves with purple undersides; nodding seed heads; clumping growth habit; annual or perennial lifecycle. The plant produces numerous seeds that remain viable in soil.

Grass-specific herbicides containing fluazifop or sethoxydim provide control. Regular mowing prevents seed production. Maintaining dense vegetation helps prevent establishment.

Pros:

• Grass-specific herbicide effective
• Cultural control works
• Mowing prevents seed

Cons:

• Prolific seed production
• Can be persistent
• Seeds remain viable for years

23. Purpleleaf Panicgrass (Panicum spp.) – Purple-Undersided Grass Weed

Purpleleaf panicgrass is a perennial grass weed with purple-tinged leaves and open seed heads. This plant invades disturbed areas, pastures, and roadsides. The leaves have a distinctive purple or reddish tint on the undersides.

Key identification features: Grass-like leaves with purple undersides; open, airy seed heads; clumping growth habit; perennial lifecycle. The plant produces numerous seeds that remain viable in soil.

Grass-specific herbicides containing fluazifop or sethoxydim provide control. Regular mowing prevents seed production. Maintaining dense vegetation helps prevent establishment.

Pros:

• Grass-specific herbicide effective
• Cultural control works
• Mowing prevents seed

Cons:

• Prolific seed production
• Can be persistent
• Seeds remain viable for years

24. Purpleleaf Foxtail (Setaria spp.) – Purple-Undersided Grass Weed

Purpleleaf foxtail is an annual grass weed with purple-tinged leaves and bristly seed heads. This plant invades disturbed areas, gardens, and roadsides. The leaves have a distinctive purple or reddish tint on the undersides.

Key identification features: Grass-like leaves with purple undersides; bristly, foxtail-like seed heads; clumping growth habit; annual lifecycle. The plant produces numerous seeds that remain viable in soil.

Grass-specific herbicides containing fluazifop or sethoxydim provide control. Regular mowing prevents seed production. Maintaining dense vegetation helps prevent establishment.

Pros:

• Grass-specific herbicide effective
• Annual lifecycle
• Mowing prevents seed

Cons:

• Prolific seed production
• Can be persistent
• Seeds remain viable for years

25. Purpleleaf Crabgrass (Digitaria spp.) – Purple-Undersided Summer Grass

Purpleleaf crabgrass is a summer annual grass weed with purple-tinged leaves and sprawling growth. This plant invades lawns, gardens, and disturbed areas. The leaves have a distinctive purple or reddish tint on the undersides.

Key identification features: Grass-like leaves with purple undersides; sprawling, mat-forming growth; finger-like seed heads; annual lifecycle. The plant produces numerous seeds that remain viable in soil.

Pre-emergent herbicides applied in early spring provide effective control. Post-emergent grass-specific herbicides containing fluazifop or sethoxydim are effective on actively growing plants. Maintaining thick, healthy turf prevents establishment.

Pros:

• Pre-emergent control available
• Annual lifecycle
• Responds to cultural practices

Cons:

• Prolific seed production
• Seeds remain viable for years
• Can be persistent

26. Purpleleaf Goosegrass (Eleusine indica) – Purple-Undersided Summer Grass

Purpleleaf goosegrass is a summer annual grass weed with purple-tinged leaves and prostrate growth. This plant invades lawns, gardens, and disturbed areas. The leaves have a distinctive purple or reddish tint on the undersides.

Key identification features: Grass-like leaves with purple undersides; prostrate, mat-forming growth; finger-like seed heads; annual lifecycle. The plant produces numerous seeds that remain viable in soil.

Pre-emergent herbicides applied in early spring provide effective control. Post-emergent grass-specific herbicides containing fluazifop or sethoxydim are effective on actively growing plants. Maintaining thick, healthy turf prevents establishment.

Pros:

• Pre-emergent control available
• Annual lifecycle
• Responds to cultural practices

Cons:

• Prolific seed production
• Seeds remain viable for years
• Can be persistent

27. Purpleleaf Bermudagrass (Cynodon spp.) – Purple-Undersided Creeping Grass

Purpleleaf bermudagrass is a warm-season perennial grass with purple-tinged leaves and aggressive creeping growth. This plant invades lawns, gardens, and disturbed areas. The leaves have a distinctive purple or reddish tint on the undersides.

Key identification features: Grass-like leaves with purple undersides; creeping stolons and rhizomes; finger-like seed heads; perennial lifecycle. The plant spreads rapidly through stolons and rhizomes.

Systemic herbicides containing glyphosate applied in late summer to fall provide control. Physical barriers installed 6-8 inches deep help prevent spread. Maintaining thick, healthy turf helps prevent establishment.

Pros:

• Systemic herbicides effective
• Barriers prevent spread
• Can be controlled with persistence

Cons:

• Aggressive spread
• Multiple seasons needed
• Labor intensive

28. Purpleleaf Stiltgrass (Microstegium vimineum) – Purple-Undersided Invasive Grass

Purpleleaf stiltgrass is an invasive annual grass with purple-tinged leaves and sprawling growth. This plant invades woodlands, gardens, and disturbed areas. The leaves have a distinctive purple or reddish tint on the undersides.

Key identification features: Grass-like leaves with purple undersides; sprawling growth; slender seed heads; annual lifecycle. The plant produces numerous seeds that remain viable in soil.

Pre-emergent herbicides applied in early spring provide effective control. Post-emergent grass-specific herbicides containing fluazifop or sethoxydim are effective on actively growing plants. Maintaining dense vegetation helps prevent establishment.

Pros:

• Pre-emergent control available
• Annual lifecycle
• Responds to cultural practices

Cons:

• Highly invasive
• Prolific seed production
• Can be persistent

29. Purpleleaf Yellow Woodsorrel (Oxalis stricta) – Purple-Undersided Shamrock Weed

Purpleleaf yellow woodsorrel is a low-growing weed with purple-tinged leaves and yellow flowers. This plant forms patches in lawns, gardens, and disturbed areas. The leaves have a distinctive purple or reddish tint on the undersides and fold at night.

Key identification features: Trifoliate leaves with purple undersides; heart-shaped leaflets that fold at night; yellow flowers; low-growing habit. The plant spreads through seeds and small bulbils.

Broadleaf herbicides containing 2,4-D or dicamba provide control. Maintaining thick, healthy turf prevents establishment. Manual removal is difficult due to the bulbils that can regenerate.

Pros:

• Attractive appearance
• Can be controlled with herbicides
• Some species are edible

Cons:

• Spreads through bulbils and seeds
• Can be persistent
• Difficult to remove manually

30. Purpleleaf Nutsedge (Cyperus rotundus) – Purple-Undersided Sedge Weed

Purpleleaf nutsedge is a problematic sedge weed with purple-tinged leaves and extensive underground tubers. This aggressive weed invades lawns, gardens, and agricultural fields. The leaves have a distinctive purple or reddish tint on the undersides.

Key identification features: Grass-like leaves with purple undersides; triangular stems; purple flower heads; extensive rhizome system with tubers. The plant grows 6-18 inches tall and produces small purple-brown flowers.

Sedge-specific herbicides containing halosulfuron or sulfentrazone provide control. Improving drainage and reducing soil compaction helps prevent establishment. Multiple applications over 2-3 years are typically necessary for eradication.

Pros:

• Sedge-specific herbicides available
• Drainage improvement helps
• Targeted approach works

Cons:

• 2-3 years of treatment needed
• Tubers persist in soil
• Can be persistent

7 Essential Strategies For Managing Weeds With Purple Under Leaves

• Identify the species accurately: Different purple-undesided weeds require different control approaches. Accurate identification is essential for selecting the most effective control methods. Use identification guides, extension services, or plant identification apps to confirm species.
• Apply herbicides at the right time: Systemic herbicides are most effective when applied in spring and fall when plants are actively growing. For winter annuals like purple deadnettle and henbit, early spring applications are most effective before flowering.
• Prevent seed production: Remove flowers and seed heads before they mature to prevent seed dispersal. Many purple-undesided weeds produce thousands of seeds that can remain viable in soil for years. Regular monitoring and prompt removal is essential.
• Combine control methods: Integrated weed management that combines cultural practices, manual removal, and targeted herbicide applications provides the best long-term control for purple-undesided weeds. Cultural practices prevent establishment, while herbicides control existing infestations.
• Maintain dense vegetation: Maintaining dense, healthy turf or competitive vegetation is the best defense against weed establishment. Proper mowing, fertilization, and irrigation promote vigorous growth that outcompetes weeds.
• Address underlying issues: Many purple-undesided weeds indicate specific problems. Purple deadnettle and henbit indicate disturbed soil. Purple nutsedge indicates moisture and compaction issues. Addressing these issues helps prevent weed establishment.
• Monitor and persist: Purple-undesided weeds often require repeated treatments over several seasons for complete control. Regular monitoring for new growth or seedlings is essential. Prompt treatment of new plants prevents establishment.

Frequently Asked Questions About Weeds With Purple Under Leaves

1. What weeds have purple under leaves?

Many weeds have purple under leaves, including purple deadnettle, henbit, purpleleaf plantain, purpleleaf sorrel, purpleleaf persicaria, and various species of pigweed, dock, thistle, and nightshade. These weeds are common in lawns, gardens, and disturbed areas.

2. Why do some weeds have purple under leaves?

The purple coloration on the undersides of weed leaves is caused by pigments called anthocyanins. These pigments serve various functions including protection from UV radiation, defense against herbivores, and adaptation to environmental stress such as cold temperatures or nutrient deficiency.

3. Are weeds with purple under leaves more aggressive?

Not necessarily, but many weeds with purple under leaves are particularly aggressive because their pigmentation helps them thrive in conditions where green plants struggle. Purple deadnettle and henbit are early spring emergers that complete their lifecycle before many other plants emerge.

4. What herbicides kill weeds with purple under leaves?

Broadleaf herbicides containing 2,4-D, dicamba, or triclopyr are effective against most purple-undesided broadleaf weeds. For sedges like purple nutsedge, sedge-specific herbicides containing halosulfuron or sulfentrazone are needed. Always follow label instructions carefully.

5. Can I prevent purple-undesided weeds from growing in my lawn?

Yes, maintaining a thick, healthy lawn through proper mowing, watering, and fertilization is the best prevention. Address underlying issues like poor soil, compaction, and drainage problems. Pre-emergent herbicides can prevent germination of annual weeds when applied at the right time.

6. Are weeds with purple under leaves poisonous?

Some weeds with purple under leaves are poisonous, including purple nightshade and certain species of groundcherry. Always exercise caution when handling unknown weeds and keep children and pets away from potentially toxic plants.

7. How do I get rid of purple deadnettle in my lawn?

Control purple deadnettle by applying broadleaf herbicides containing 2,4-D or dicamba in early spring before flowering. Maintain thick, healthy turf through proper cultural practices. Manual removal is effective for small infestations before seed set.

Conclusion

Weeds with purple under leaves represent some of the most distinctive and persistent invaders in gardens, lawns, and landscapes. From the early spring emergence of purple deadnettle and henbit with their striking purple leaf undersides to the aggressive spread of purple nutsedge and various thistle species, these colorful weeds pose significant challenges for landowners and gardeners.

The 30 weeds examined in this guide demonstrate the diversity of species with purple or reddish undersides and the variety of management challenges they present. Understanding the specific growth habits, environmental preferences, and vulnerabilities of each species is essential for effective control. Some respond well to systemic herbicides, others require physical removal, and many need integrated strategies combining multiple approaches over several growing seasons.

Successful management of purple-undesided weeds requires patience, persistence, and a combination of cultural, mechanical, and chemical control methods. Regular monitoring, early intervention, and preventing seed production are key to reducing weed populations and preventing their spread. With the right approach, these colorful invaders can be effectively controlled and managed.