22 Weeds With Purple Flowers That Might Be in Your Garden

All gardeners, including myself, are guilty of sometimes equating the term ‘weed’ with ugliness. 

It’s true that most weeds aren’t as pretty as your average garden plant, but there are still countless weeds (some of them extremely harmful) with cute or downright beautiful flowers. These deceptively attractive weeds come in every colour, including purple.

In this article, I’ll teach you how to identify and control some of the most common weeds with purple flowers.

Life Cycles of Lawn and Garden Weeds

It’s always best to identify the exact species of weed invading your landscape. This bit of knowledge tells you a lot about the plant, including its life cycle, which can be a big help in controlling the infestation.

Annual weeds only live for a single year. These weeds sprout, flower, and produce seeds all in one growing season. Annuals often have very fast growth rates, which can make it hard to keep them under control. The good news is that preventing the weeds from going to seed can greatly reduce the number of plants that sprout in your yard and garden the following year.

Biennial weeds live for two years. It’s common for these weeds to produce only leafy growth in the first year and a flower stalk in the second. The best time to treat biennial weeds is in their first year.

Perennial weeds live for three or more years. Most die back to the ground each winter, but the root systems survive and regrow the following spring. These weeds are difficult to control because they come back year after year. During that time, they can also produce countless new plants via seeds or vegetative offshoots.

22 Weeds With Purple Flowers and How to Control Them

Identifying flowering weeds isn’t always as simple as it sounds. Many of these weeds look alike, and some even resemble desirable plants that might be growing in your garden or the local ecosystem.

This list should help you more easily ID the purple weeds in your lawn and garden and learn how to get rid of them as safely and efficiently as possible.

1. Creeping Charlie

Creeping Charlie

Glechoma hederacea

  • Life Cycle: Perennial
  • Bloom Time: Early spring
  • Toxicity: None

Creeping Charlie, or ground ivy, is a low-growing perennial with round, scalloped leaves and small, purple flowers. As the name suggests, it spreads by creeping along the ground and can quickly invade lawns and gardens.

Though creeping Charlie prefers shady, moist areas, it adapts easily to nearly all growing conditions. Preventing its presence with broadleaf pre-emergent treatments and routine pulling is the best course of action. Selective herbicides containing triclopyr are most effective on large infestations.

Some homeowners have tried to use this weed as a lawn alternative. Unfortunately, the plant employs a unique ‘lottery system’ that deprives many pollinators of essential pollen and nectar. Growing creeping Charlie on purpose is rarely recommended.

2. Purple Dead Nettle

Purple Dead Nettle

Lamium purpureum

  • Life Cycle: Annual
  • Bloom Time: Early spring to summer
  • Toxicity: None

Purple dead nettle is an annual weed most easily recognized by its squarish stems and spade-shaped leaves. The leaves tend to have a gradient effect, with the topmost foliage appearing red or purple. It also features small, purplish-pink flowers throughout much of the growing season. 

This weed typically forms dense clusters. Since it likes disturbed soil, gardens and unkempt lawns are some of the purple dead nettle’s favourite environments. 

Regular hand-pulling, mulching, and general soil maintenance can help prevent its establishment. Purple dead nettle can be a good source of food for early pollinators, so it may be beneficial to let the plant flower before pulling.

3. Henbit

Henbit

Lamium amplexicaule

  • Life Cycle: Annual
  • Bloom Time: Spring and fall
  • Toxicity: None

Henbit is an annual cool-season weed often mistaken for purple dead nettle. If you’re unsure how to tell the difference between these plants, just take a quick look at the leaves. Henbit foliage is deeply scalloped and lacks the columnar arrangement of purple dead nettle leaves. 

Henbit features small, tubular flowers that most often appear in the spring. However, a second round of blooms may also occur in the fall of the same year.

If left to its own devices, henbit can quickly take over a lawn or garden bed. Thick, healthy turf grass is a great defence against this and many other weeds. Pre-emergent herbicides applied early in the spring are also very effective at controlling this annual weed.

4. Red Clover

Red Clover

Trifolium pratense

  • Life Cycle: Perennial
  • Bloom Time: Spring to fall
  • Toxicity: Low

Just like white clover, Red clover isn’t always a weed. This perennial legume is frequently used for ground cover and as a forage crop. It can become invasive when it escapes cultivation. 

When allowed to invade meadows and other natural habitats, red clover has the potential to outcompete native plant species. In the average lawn or garden, however, this is far from the worst weed you can encounter.

Control red clover by mowing your lawn at a low setting before the flowers go to seed. Also note that, according to Pennsylvania State University, its presence may indicate that your lawn isn’t getting enough nitrogen from the soil. 

5. Wild Violet

Wild Violet

Viola sororia

  • Life Cycle: Perennial
  • Bloom Time: Early spring
  • Toxicity: None

Wild violets are broadleaf perennial weeds that often form small colonies and are notoriously difficult to control when found growing in grass. The blooms are typically purple or yellow, but this grass loving weed also comes with tiny white flowers too. also come in shades of white and yellow and have a distinctive heart shape. 

Don’t be fooled by this weed’s delicate appearance. Wild violets are incredibly tough and can withstand many common eradication methods. They are also readily self-sow.

Whether or not to remove this weed from your property is up to you. Some gardeners like the look of wild violets, and they are native to North America. The issue is that these charming flowers will eventually choke out other plants — turf grass included — if allowed to spread.

6. Canada Thistle

Canada Thistle

Cirsium arvense

  • Life Cycle: Perennial
  • Bloom Time: Summer
  • Toxicity: Low

Canada thistle is an aggressive perennial weed that crowds out practically all native plants it comes across. Its extensive root system makes it very difficult to control, even with chemical treatments. 

Various systemic herbicides are effective at killing the root system. You’ll probably need to use something stronger than, say, RoundUp. I recommend contacting your local Extension Office (or a similar service) for the safest and most efficient treatment options for your area.

Even if you can’t remove the entire plant, it’s extremely important to prevent the seeds from spreading. Cut or mow down Canada thistle as soon as flowers appear.

7. Nodding Thistle

Nodding Thistle

Carduus nutans

  • Life Cycle: Biennial
  • Bloom Time: Summer to fall
  • Toxicity: Low

Also known as musk thistle, nodding thistle is named for its large, drooping flowers. The flower heads start out green, but purple petals soon emerge from the centre. 

This biennial weed is most effectively controlled during its rosette stage — i.e., in its first year when it consists only of low-growing leaves. 

It doesn’t hurt to try hand-pulling smaller thistles, but the large taproots make manual removal quite difficult. Fortunately, popular weed killers like glyphosate and triclopyr are very effective in nodding thistles.

8. Bull Thistle

Bull Thistle

Cirsium vulgare

  • Life Cycle: Biennial
  • Bloom Time: Summer to fall
  • Toxicity: None

Bull thistle is another biennial weed that forms a low-growing rosette in its first year and flowers in its second. It creates large colonies in disturbed areas that choke out native plant and wildlife species.

As is the case with most thistles, bull thistle’s spiny leaves and stems make hand-pulling a bit tricky. Mowing or string-trimming the flower stalks before they set seed will help control its spread. Chemical products like RoundUp are most effective when applied during the rosette stage.

9. Milk Thistle

Milk Thistle Silybum marianum

Silybum marianum

  • Life Cycle: Annual or biennial
  • Bloom Time: Spring to fall
  • Toxicity: Moderate

Milk thistle is an annual or biennial weed that grows up to 6 feet tall. You can tell it apart from other thistle species by looking for the distinctively shiny, marbled leaves.

This noxious weed is toxic to livestock and extremely problematic in many types of agricultural fields. It’s less of a concern for home gardeners but should still be removed immediately if spotted.

A single milk thistle can produce thousands of seeds, and the seeds can continue to develop even in cut or mowed plant parts. It’s best to bag up removed flower heads to prevent the accidental spread of seeds.

10. Purple Starthistle

Purple Starthistle

Centaurea calcitrapa

  • Life Cycle: Biennial
  • Bloom Time: Summer to fall
  • Toxicity: Low

Purple starthistle is a formidable weed, recognized by globular, purple flowers that sit atop clusters of large, yellow spikes. It has become a problematic weed in many parts of the world, invading grasslands and agricultural areas. 

Its spiny nature deters grazing by livestock and wildlife. This results in patches of grassland that are cleared of all flora but the purple starthistle. 

Control methods include frequent mowing to prevent seed development. Young plants that are still in the rosette stage can be controlled via hand-pulling and chemical herbicides.

11. Heal-All

Heal-All

Prunella vulgaris

  • Life Cycle: Perennial
  • Bloom Time: Summer to fall
  • Toxicity: None

Heal-all, also known as self-heal, is a perennial herb with a long history in the world of traditional medicine. It’s a member of the mint family, making it closely related to other weeds on this list like creeping Charlie and purple dead nettle.

In lawns and gardens, heal-all can be quite troublesome. It forms a low-growing mat that chokes out turf grass and other desirable plants. Regular mowing, hand-pulling, and selective broadleaf herbicides can help manage its growth.

12. Purple Loosestrife

Purple Loosestrife

Lythrum salicaria

  • Life Cycle: Perennial
  • Bloom Time: Summer
  • Toxicity: Low

Purple loosestrife is one of those weeds that started out as a beloved garden plant. While it may look attractive, this plant is highly invasive, especially in wetlands. Its presence interferes with native plant species and, as a result, decreases overall biodiversity. 

Its spreading root system and adaptable nature make purple loosestrife very aggressive. Early detection and removal, including the destruction of all root fragments, are essential to controlling this weed.

Several natural wetlands have been reclaimed from purple loosestrife infestations using Galerucella beetles. These insects defoliate the loosestrife while leaving desirable, native plants more or less alone.

13. Bugleweed

Bugleweed

Ajuga spp.

  • Life Cycle: Annual or perennial
  • Bloom Time: Spring to early summer
  • Toxicity: Low

Bugleweed is a popular ground cover for shady areas. In some climates, however, it can escape cultivation and spread aggressively via horizontal stems called stolons. 

While bugleweed’s spreading growth habit is great for choking out weeds and it has flowers that look like lavender, it can also pose a threat to desirable plants like turf grass. It’s very common for cultivated bugleweed to escape garden beds and take over adjacent lawns.

Hand-pulling is effective for small areas. For larger areas, a selective broadleaf herbicide will be most reliable.

14. Crown Vetch

Crown Vetch

Securigera varia

  • Life Cycle: Perennial
  • Bloom Time: Late spring to summer
  • Toxicity: Moderate

Crown vetch is a legume historically used for erosion control and soil improvement due to its nitrogen-fixing properties. It has largely fallen out of favour as a cover crop because it can become invasive in many regions. 

This weed has pinnately compound leaves that somewhat resemble a fern. Its flowers are pinkish-purple and, when given a closer look, reminiscent of a pea blossom.

Crown vetch uses rhizomes, or underground stems, to form dense colonies that can crowd out native vegetation. Recommended control methods include mowing down plants before they produce seeds and using selective herbicides.

15. Bush Vetch

Bush Vetch

Vicia sepium

  • Life Cycle: Perennial
  • Bloom Time: Late spring to summer
  • Toxicity: Moderate

Bush vetch is a vine belonging to the legume family. It uses small tendrils at the ends of its leaves to grab onto nearby structures, including other plants.

While beneficial in certain habitats, bush vetch can be a nuisance in gardens due to its rapid growth and tendency to climb on and smother other plants. Regular mowing can prevent it from setting seed. Hand-pulling is also effective as long as you remove the entire root system.

16. Comfrey

Comfrey

Symphytum officinale

  • Life Cycle: Perennial
  • Bloom Time: Late spring to early summer
  • Toxicity: Moderate

Comfrey was introduced to much of the world as a medicinal herb. Its native range covers parts of Europe and Asia. Unfortunately, the plant’s growth habit makes it extremely invasive in some environments.

This weed has purple, bell-shaped flowers that sit atop large, semi-fuzzy leaves. It may be mistaken for a variety of bluebell. Some plants can reach over 3 feet tall when in bloom.

Comfrey is often very difficult to remove because whole new plants can grow from small root fragments left behind in the soil. Hand-pulling when the soil is damp will make the taproot less likely to break off.

17. Spotted Knapweed

Spotted Knapweed

Centaurea stoebe

  • Life Cycle: Biennial or perennial
  • Bloom Time: Early summer
  • Toxicity: None

Spotted knapweed is a serious nuisance in meadows, pastures, and agricultural fields. If you live near any of these terrains, there’s a good chance this weed will try to invade your lawn or garden as well. 

It’s easy to mistake this weed for a type of thistle. Despite the striking similarities, spotted knapweed lacks spines of any kind. It does, however, produce a potential skin irritant, and gloves should be worn when pulling this plant.

Stopping the spread of spotted knapweed is just as important as killing off existing plants. Mow down plants before they flower and go to seed. 

18. Dove’s Foot Cranesbill

Dove’s Foot Cranesbill

Geranium molle

  • Life Cycle: Annual
  • Bloom Time: Summer to early fall
  • Toxicity: Low

Dove’s foot cranesbill is a hardy geranium native to Europe. It is an aggressive spreader often classified as a weed in other parts of the world. 

The main problem with the dove’s foot cranesbill is how easily it spreads by seed. The seeds can and will take root in any recently disturbed soil, making them a common invader of home gardens. 

Pre-emergent herbicides are incredibly effective on this weed due to its annual life cycle. Hand-pull any plants that make it past your first line of defence.

19. Spanish Bluebell

Spanish Bluebell

Hyacinthoides hispanica

  • Life Cycle: Perennial
  • Bloom Time: Early spring
  • Toxicity: High

Spanish bluebell is an attractive bulb that blooms alongside tulips, daffodils, and other spring perennials. Its bell-shaped flowers come in many colours but are usually bluish-purple. 

Spanish bluebells may naturalize in regions like North America but are a much bigger problem in the UK. This is because they can interbreed with native species of bluebell, contaminating the local gene pool.

Remove spent flowers before they develop into seed heads. You can remove the entire plant by carefully digging up the bulb.

20. Bittersweet Nightshade

Bittersweet Nightshade

Solanum dulcamara

  • Life Cycle: Perennial
  • Bloom Time: Spring to fall
  • Toxicity: High

Bittersweet nightshade is a vine or sprawling shrub with purple and yellow blossoms that look a lot like the flowers of a tomato or pepper plant. Distinctive red berries follow the flowers. 

Though native to Europe and Asia, it has invaded large swathes of North America. Note that all parts of the bittersweet nightshade are toxic to humans and pets. 

Hand-pulling is a good strategy, but you must be careful to remove the entire root system. This weed also responds well to herbicides containing glyphosate.

21. Creeping Bellflower

Creeping Bellflower

Campanula rapunculoides

  • Life Cycle: Perennial
  • Bloom Time: Early summer to fall
  • Toxicity: None

Creeping bellflower is a beautiful perennial that looks right at home in most gardens. Sadly, its beauty belies its invasive nature. 

This species of bellflower reproduces by seeds and creeping rhizomes. The result is a flower that spreads far and wide, often forming dense colonies. 

You may be able to hand-pull creeping bellflower found in your lawn or garden before it gets too established. This weed doesn’t always respond to chemical herbicides, but clopyralid and glyphosate are both strongly recommended.

22. Common Burdock

Common Burdock

Arctium minus

  • Life Cycle: Biennial
  • Bloom Time: Summer
  • Toxicity: None

Common burdock is infamous for its spiny burs that cling to clothing and animal fur. It has large, heart-shaped leaves that are sometimes mistaken for wild rhubarb. 

Burdock will grow almost anywhere and is extremely stubborn once established due to a deep taproot. Be sure to remove flower heads before the plant can produce seeds. Herbicides aren’t very effective on this weed, so persistent maintenance is often the only option.

FAQs Purple Weeds in Lawn

How do you control ground ivy in the grass?

Ground ivy, or creeping Charlie, is difficult to eradicate once it becomes established. Hand-pulling can be very effective but is time-consuming. Try using a selective herbicide containing triclopyr to kill large infestations. Keeping your lawn 3 inches tall and well-fed will make it less appealing to ground ivy plants.

Why are there purple flowers on my lawn?

Several common lawn weeds bear purple flowers, including red clover, creeping Charlie, henbit, and purple dead nettle. All of these weeds are relatively short, so you may not notice the foliage among the blades of green turf grass. Frequent mowing and the use of selective herbicides may help.

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