When you’re a gardener, weeds are an unfortunate fact of life.
Sometimes they look nice, with attractive flowers when they bloom.
But it leads to the plant setting seed and spreading. Which means a bigger clear up job.
Although it’s best to deal with them quickly, it’s important to identify them first if you can.
Different types of weeds respond best to different methods of eradication and prevention.
So if you’re wondering ‘what are the weeds with purple flowers called?’, I think I can help you.
7 Common Weeds With Purple Flowers
Although there are many weeds with purple flowers, these are some of the ones you’re most likely to stumble across:
- Creeping Charlie
- Purple Deadnettle
- Wild Violet
- Violet Wood Sorrel
- Red Clover
- Purple Loosestrife
Let’s take a closer look:
Henbit (Lamium amplexicaule)
Henbit is an edible weed that takes its name from its popularity with chickens. It’s also one of the most well-known purple flowering weeds.
It’s not unusual to find it growing around buildings, fallow areas, fields, or around your yard. If you’ve found a weed with purple flowers infesting your healthy lawn, then it probably isn’t henbit. But if your lawn is thin and weak, then it has a chance to take hold.
Here are some things to look out for to distinguish it from other weeds:
If you look closely, you’ll see the green stems have a square shape. And they can become purple as they age. With occasional rooting at the lower nodes.
The leaves come in opposite pairs and are heart-shaped or rounded, with deep lobes. And the edges have distinctive rounded teeth. On the upper leaf surface, the veins are depressed, which creates a wrinkled appearance.
If it’s henbit, you’ll notice the leaves further up the plant are attached to the upper stem. Whereas the leaves lower down grow on stalks.
It spreads through seeds. So the key to controlling it is early identification.
Seed dispersal occurs after it flowers in late spring. So using a herbicide in early spring to kill the plant is the best way to prevent seed production.
If the plant is already flowering, then it’s too late. The herbicide probably won’t be effective in preventing seed dispersal.
If you find the plant while it’s still growing, then another method you can use is to pull it out by hand. Making sure to carefully dispose of all parts to prevent regrowth.
If the seeds have already dispersed around your yard, then you can use a pre-emergent herbicide in the early fall to prevent germination.
Creeping Charlie (Glechoma hederacea)
A common nuisance in gardens, if you’ve got a purple flowered weed taking over your lawn then there’s a good chance that this is the culprit.
Also called ground ivy, creeping charlie is a common broadleaf weed that can quickly take over your yard if you leave it.
It grows low to the ground, usually about 1 inch high, and quickly forms a dense mat of leaves and stems as it spreads.
Other distinguishing features that can help you identify it include a square stem and bright green leaves with scalloped edges, either kidney shaped or round.
Leaves grow in opposite pairs on either side of the stem attached to a node. And you can see the blueish purple flowers along the stem when it blooms in spring.
It’s important to know that creeping charlie finds it easiest to colonize lawns that aren’t well cared for. So to keep it away it’s a good idea to regularly mow, fertilize, and water your lawn to help it grow thick and strong. Leaving no room for weeds to become established.
It spreads from rhizomes, stems that can root, and seeds. And it can be difficult to get rid of. Because even after you dig it out of the soil, leaving any part of its rhizomes behind allows the plant to regrow.
If you catch small patches of the plant early in the spring, then it can be worth having a go at hand pulling it. But this often takes a number of attempts to completely eradicate the plant.
The easiest way to get rid of it is to use a post emergent weed killer that can tackle broadleaf weeds.
But make sure the product specifies its use for creeping charlie because not all broadleaf weed killers can do the job.
It’s also important to choose a systemic weed killer. These are absorbed by the plant and kill it from the inside including the roots.
And if you’re using it on grass, make sure it’s selective for broadleaf weeds so it won’t cause harm. See our advice on the best weed killers for lawns.
Purple Deadnettle (Lamium purpureum)
Purple deadnettle is a weed in the mint family that’s sometimes mistaken for Henbit. But there are differences when you know what to look for.
Like Henbit, it has a square stem. But the heart-shaped leaves have a gentler scalloping at the margins. And unlike henbit, the leaves aren’t attached to the central stem directly.
The leaves are arranged opposite each other. And closer examination reveals a covering of fine hair.
Purple deadnettle usually grows low to the ground. But it can sometimes grow as tall as 8 to 10 inches.
And it prefers growing in moist areas. So it’s commonly found in fallow fields, drainage ditches, and on the edges of woodlands.
But, if you’ve got irrigation in your yard, or you’re near to woodlands or a field, then you could find purple deadnettle encroaching onto your lawn.
If you find a small number of plants then it’s not too difficult to pull them out by hand.
For a larger infestation, it’s more effective to use a post emergent herbicide in the early spring. If you catch it before it blooms then you can prevent it from producing seeds and spreading further.
As the weed gets bigger, herbicides are less likely to control it. But as its a winter annual that dies in the summer, applications of weed killer in late spring aren’t usually necessary.
It produces thousands of seeds at a time. And if they’ve spread, then it’s a good idea to use a pre-emergent herbicide in the late fall or early winter. This will stop the seeds germinating.
Wild Violet (Viola sororia)
Some people are happy to have wild violets growing in their yard. The pretty blue-purple blooms make a good addition to a wild garden.
But if it’s growing in your well cared for lawn then that’s another matter.
When young, it prefers a moist and shady growing environment. But the mature plants can spread to sunnier locations and quickly take over.
You can identify wild violet before it flowers by looking at the leaves. They are heart shaped with a pointed tip and rounded teeth at the edge. The flowers have 5 petals and appear from April to June.
Violets can spread by seed and by short, thick rhizomes, similar in size to your little finger.
For chemical control using a broadleaf weed killer, look for products that contain triclopyr, 2,4-D, dicamba, and MCPP.
You often need multiple applications to control an infestation. Why?
Because although its use in the spring will control the plants already growing, more plants can germinate and grow from dormant rhizomes between April and September. This long emergence window makes it a difficult plant to completely get rid of.
Violet Wood Sorrel (Oxalis violacea)
Sometimes mistaken for clover, violet wood sorrel is an edible perennial weed. It produces many attractive flowers when in bloom. And some gardeners choose to plant it in ornamental gardens and pots.
The plant grows 6-10 inches tall. And features bell-shaped, pink-purple flowers at the end of thin stems, each with 5 petals. The flowers are usually clustered together in groups of 4-19.
The green leaves consist of 3 heart shaped leaflets. And sometimes you’ll see purplish markings underneath.
The plant blooms from April to July. And then again from September to November.
Wood Sorrel rapidly spreads in dry, open areas due to its seed capsules. Their fragile casing bursts when touched spreading the contents throughout your yard.
It’s particularly likely to invade lawns that are sparse and poorly looked after. But it will sometimes get a foothold in a healthy lawn.
You can get rid of it by hand. But this is best done soon after it starts to grow, as its root system grows deep and becomes difficult to pull out. And you have to make sure you get all of the root or it will grow back.
If you have a larger infestation then it’s best to head straight for the broadleaf weed killer.
Red Clover (Trifolium pratense)
This short lived perennial easily grows in most soil types. And it can withstand varying conditions including cool temperatures and drought.
It’s often used by farmers as a cover crop because it fixes nitrogen in the soil. And it”s also useful as a forage crop or hay.
It’s easy to identify:
From late spring to early summer it produces distinctive pink-purple flower heads. With each head consisting of numerous small flowers. The flower heads are eventually replaced by seed pods
Its hairy stems grow either spreading or erect and form clumps. And the leaves consist of 3 oblong or oval leaflets, positioned alternately on the plant stem. The leaf margins are smooth and have very small hairs that project away from the plant.
If it gets in your yard it can displace desirable plants. Similar to most lawn weeds, thin and under-fertilized lawns are susceptible to being invaded. So a good way to limit its spread is by making sure you have a thick and healthy lawn.
Getting rid of it by hand can be challenging, as it grows a very deep taproot. So instead, it’s best controlled by weed killers containing, fluroxypyr, dicamba, and quinclorac, applied in the fall.
Purple Loosestrife (Lythrum salicaria)
Purple loosestrife is a noxious weed that you’ll sometimes find growing around lakeshores, ponds, wetlands, ditches, and wet pastures.
It’s a tall weed with purple flowers that typically grows between 6 and 10 feet. And features 4-6 sided stems with smooth-edged leaves, and many small 5-7 petalled flowers growing in tall spikes.
Of the weeds that grow purple flowers on our list, this one has the potential to be the biggest problem.
Spreading by seed, rhizomes, taproot, and vegetative growth, it’s hard to control when it’s growing in the right conditions. And it can take over a site in a single year if left unchecked. Choking out plant life in the area, destroyng sources of food for other wildlife.
Cutting off the flower heads during the flowering season — late June to early September — can help to limit its spread, as each plant produces millions of seeds. Make sure you dispose of them carefully by bagging and taking to a landfill, or by burning.
You can pull young plants from the ground. And you can dig out older plants. But make sure to remove all the roots and rhizomes. The same disposal rules apply.
For large infestations, glyphosate herbicides can do the job. But be careful using these around aquatic sites. You should get a product that’s suitable for that environment, such as PondMaster.