Gardening Guides
The Essential Weed Hit List
Learn how to recognize and control 5 weedy plants that have achieved invasive status throughout the U.S.
Whenever people settle into a new environment, weeds are sure to follow. Some of these are unintended, while others are plants we chose for our gardens but have escaped. Still others have been widely distributed with the intent of solving some environmental problem, such as erosion, but they lack natural controls and end up running wild. Some of these weeds are a nuisance, messing up the otherwise neat appearance of our lawns and gardens or competing with our vegetables for resources. And some weeds take this further, spreading across our lawns and gardens and into natural or unmanaged areas, and upsetting or displacing the native plants and animals that have evolved to live in those areas. This latter group is considered to be invasive.
Photo by Frank Mayfield
By the end of May, this patch of garlic mustard in a woodland edge habitat has already achieved peak bloom, and seedpods are beginning to form.
1. Garlic Mustard
(Alliaria petiolata)
Where you’ll see it: From Quebec, Canada, south to Georgia and west to Utah and the Pacific Northwest, excluding Montana, Wyoming and South Dakota
Where it’s invasive: AK, AL, CT, DC, DE, GA, IA, IL, IN, KY, MA, MD, ME, MI, MO, NC, NH, NJ, NY, OH, OR, SC, PA, TN, VA, VT, WA, WI and WV
Garlic mustard is often found growing in open woodlands and shaded garden edges. It is a biennial, meaning that it takes two years to complete its life cycle. The first year is spent as a low rosette of roundish to heart-shaped leaves, during which time it is storing up energy. These rosettes overwinter, and in its second year, the plant puts up a much taller flowering stem with many coarsely toothed leaves. In midspring, the upper half of the plant is covered with clusters of four-petaled white flowers. These flowers mature into long seedpods that ripen in late summer, when they split open and release their tiny seeds. A single garlic mustard plant can release up to 6,000 seeds.
Why it’s a problem: While the white blooms are visited by many insect pollinators, the foliage is largely ignored by native animals and insects. This lack of natural controls gives garlic mustard an advantage over native species, leading to its ability to take over large areas of woodlands. Garlic mustard also secretes chemicals that inhibit the growth of other nearby plants. One of these is known to inhibit the growth of mycorrhizal fungi needed by tree seedlings to grow.
How to spot it: Garlic mustard can be recognized by its reticulated leaves (showing a network of deep veins) in the rosette stage and the coarsely toothed, heart-shaped leaves on the flowering stalk. When crushed, the leaves have a garlicky odor. The four-petaled white flowers are similar to others in the mustard family. The plant forms a fleshy white taproot that stores up energy from its first season.
It can be confused with violets in the rosette stage. Violets do not have the deeply veined leaves of garlic mustard, and the leaves are somewhat thicker. Violets lack the garlic odor and grow from a shallow rhizome instead of a taproot.
How to get rid of it: Since garlic mustard is a biennial, the key to controlling it is to keep it from reproducing. Plants can be pulled at any time; however, care must be taken in late summer and fall when the seedpods are ripe so as not to disperse more seeds. As much of the root as possible should be removed, since plants may resprout from root fragments. Pulling is easier when the soil is slightly moist. Using a slow, steady tension, a large portion of the root can often be removed from the soil. First-year rosettes can be pulled and left in the sun to dry out — they will not survive. Flowering stalks should be pulled carefully and dried in the sun before being bagged and disposed of in a landfill. Composting these stalks risks spreading seeds or having the root fragments catch hold in the compost pile. If not dried out or bagged, flowering stalks are known to continue to set and ripen seeds even though they have been pulled out of the soil.
A broadleaf or nonselective herbicide can be effective when used in the early spring or late fall, particularly before other desired plants leaf out (spring) or have died back for the winter. (Note: Herbicides should be used carefully and only as recommended on the package instructions.) Since garlic mustard is evergreen, it’s easy to spot in early spring before other plants have sprouted.
Seeds remain viable in the soil for five to eight years. Complete removal will take a number of years to fully deplete the seed bank. Also, you will need to remain vigilant for new invasions; however, it’s much easier to eliminate a new occurrence than it is to remove an established infestation.
1. Garlic Mustard
(Alliaria petiolata)
Where you’ll see it: From Quebec, Canada, south to Georgia and west to Utah and the Pacific Northwest, excluding Montana, Wyoming and South Dakota
Where it’s invasive: AK, AL, CT, DC, DE, GA, IA, IL, IN, KY, MA, MD, ME, MI, MO, NC, NH, NJ, NY, OH, OR, SC, PA, TN, VA, VT, WA, WI and WV
Garlic mustard is often found growing in open woodlands and shaded garden edges. It is a biennial, meaning that it takes two years to complete its life cycle. The first year is spent as a low rosette of roundish to heart-shaped leaves, during which time it is storing up energy. These rosettes overwinter, and in its second year, the plant puts up a much taller flowering stem with many coarsely toothed leaves. In midspring, the upper half of the plant is covered with clusters of four-petaled white flowers. These flowers mature into long seedpods that ripen in late summer, when they split open and release their tiny seeds. A single garlic mustard plant can release up to 6,000 seeds.
Why it’s a problem: While the white blooms are visited by many insect pollinators, the foliage is largely ignored by native animals and insects. This lack of natural controls gives garlic mustard an advantage over native species, leading to its ability to take over large areas of woodlands. Garlic mustard also secretes chemicals that inhibit the growth of other nearby plants. One of these is known to inhibit the growth of mycorrhizal fungi needed by tree seedlings to grow.
How to spot it: Garlic mustard can be recognized by its reticulated leaves (showing a network of deep veins) in the rosette stage and the coarsely toothed, heart-shaped leaves on the flowering stalk. When crushed, the leaves have a garlicky odor. The four-petaled white flowers are similar to others in the mustard family. The plant forms a fleshy white taproot that stores up energy from its first season.
It can be confused with violets in the rosette stage. Violets do not have the deeply veined leaves of garlic mustard, and the leaves are somewhat thicker. Violets lack the garlic odor and grow from a shallow rhizome instead of a taproot.
How to get rid of it: Since garlic mustard is a biennial, the key to controlling it is to keep it from reproducing. Plants can be pulled at any time; however, care must be taken in late summer and fall when the seedpods are ripe so as not to disperse more seeds. As much of the root as possible should be removed, since plants may resprout from root fragments. Pulling is easier when the soil is slightly moist. Using a slow, steady tension, a large portion of the root can often be removed from the soil. First-year rosettes can be pulled and left in the sun to dry out — they will not survive. Flowering stalks should be pulled carefully and dried in the sun before being bagged and disposed of in a landfill. Composting these stalks risks spreading seeds or having the root fragments catch hold in the compost pile. If not dried out or bagged, flowering stalks are known to continue to set and ripen seeds even though they have been pulled out of the soil.
A broadleaf or nonselective herbicide can be effective when used in the early spring or late fall, particularly before other desired plants leaf out (spring) or have died back for the winter. (Note: Herbicides should be used carefully and only as recommended on the package instructions.) Since garlic mustard is evergreen, it’s easy to spot in early spring before other plants have sprouted.
Seeds remain viable in the soil for five to eight years. Complete removal will take a number of years to fully deplete the seed bank. Also, you will need to remain vigilant for new invasions; however, it’s much easier to eliminate a new occurrence than it is to remove an established infestation.
Japanese honeysuckle displays its blooms at the beginning of June. The flowers open white, then turn yellow as they age.
2. Japanese Honeysuckle
(Lonicera japonica)
Where you’ll see it: From Maine south to Florida and west to California and Washington, excluding the northern Plains and Rocky Mountain states and Oregon
Where it’s invasive: AL, CT, DC, DE, FL, GA, HI, IL, IN, KS, KY, MA, MD, MI, MO, NC, NH, NJ, NY, OH, OK, PA, RI, SC, TN, TX, VA, VI, VT, WI and WV
Why it’s a problem: Japanese honeysuckle is a woody perennial vine introduced from Asia. This semievergreen vine readily climbs up and over trees and shrubs. Its tightly twining habit chokes the growth of trees, leading to their early demise. It can also out-compete the plants it grows over for sunlight. The dense growth that concentrates in the treetops can break branches and even topple some trees. If there is nothing to grow upon, Japanese honeysuckle will act as a ground cover, snaking along the ground until it finds some vertical support. It grows best in part to full sun in moist soils. It is tolerant of heavy shade, growing slowly until it finds a sunny opening. Typical habitats include the edges of fields, hedgerows, forest openings and roadsides.
Spring-blooming flowers are pollinated by many insects as well as hummingbirds. Birds and small mammals eat the berries, which lead to wide dispersal in the environment. Although it provides some use to birds and other animals, the plant’s lack of natural “enemies” allows it to out-compete native plants and other desirable vegetation.
How to spot it: The leaves of Japanese honeysuckle grow in pairs on the opposite side of its leaf nodes all along the stem. Most of the leaves are oblong to ovate, with a small, sharp tip. Occasionally, some of the leaves will be lobed. In midspring, the vines bloom with sweetly scented white flowers, which turn yellow as they age. The flowers give way to dark purple to black berries in late summer.
How to get rid of it: Japanese honeysuckle puts down additional roots at the leaf nodes along the stem where it grows along the ground. One of the keys to controlling Japanese honeysuckle is to keep it from setting and spreading seeds. Since it blooms best in sun, cutting climbing vines within a foot of the ground before the flowers have had a chance to develop seeds will prevent a new crop. The upper portions of vine can be left in the tree canopy to dry out. Long runners are fairly easy to pull out, and larger clumps can be dug out. As much of the root as possible should be removed. To prevent pulled vines from rerooting elsewhere, they should be bagged and put in the landfill or left in the sun to dry out completely, then segregated from other yard waste to decompose.
For places where digging is not practical, treating the stumps with an herbicide solution is effective for killing off that clump. Since Japanese honeysuckle roots at multiple points along the vine, treating the cut ends is only effective up to the nearest set of roots. Spraying the foliage with herbicides labeled for use on Japanese honeysuckle is effective whenever it is actively growing. Care must be taken to avoid spraying onto the foliage of desired plants.
2. Japanese Honeysuckle
(Lonicera japonica)
Where you’ll see it: From Maine south to Florida and west to California and Washington, excluding the northern Plains and Rocky Mountain states and Oregon
Where it’s invasive: AL, CT, DC, DE, FL, GA, HI, IL, IN, KS, KY, MA, MD, MI, MO, NC, NH, NJ, NY, OH, OK, PA, RI, SC, TN, TX, VA, VI, VT, WI and WV
Why it’s a problem: Japanese honeysuckle is a woody perennial vine introduced from Asia. This semievergreen vine readily climbs up and over trees and shrubs. Its tightly twining habit chokes the growth of trees, leading to their early demise. It can also out-compete the plants it grows over for sunlight. The dense growth that concentrates in the treetops can break branches and even topple some trees. If there is nothing to grow upon, Japanese honeysuckle will act as a ground cover, snaking along the ground until it finds some vertical support. It grows best in part to full sun in moist soils. It is tolerant of heavy shade, growing slowly until it finds a sunny opening. Typical habitats include the edges of fields, hedgerows, forest openings and roadsides.
Spring-blooming flowers are pollinated by many insects as well as hummingbirds. Birds and small mammals eat the berries, which lead to wide dispersal in the environment. Although it provides some use to birds and other animals, the plant’s lack of natural “enemies” allows it to out-compete native plants and other desirable vegetation.
How to spot it: The leaves of Japanese honeysuckle grow in pairs on the opposite side of its leaf nodes all along the stem. Most of the leaves are oblong to ovate, with a small, sharp tip. Occasionally, some of the leaves will be lobed. In midspring, the vines bloom with sweetly scented white flowers, which turn yellow as they age. The flowers give way to dark purple to black berries in late summer.
How to get rid of it: Japanese honeysuckle puts down additional roots at the leaf nodes along the stem where it grows along the ground. One of the keys to controlling Japanese honeysuckle is to keep it from setting and spreading seeds. Since it blooms best in sun, cutting climbing vines within a foot of the ground before the flowers have had a chance to develop seeds will prevent a new crop. The upper portions of vine can be left in the tree canopy to dry out. Long runners are fairly easy to pull out, and larger clumps can be dug out. As much of the root as possible should be removed. To prevent pulled vines from rerooting elsewhere, they should be bagged and put in the landfill or left in the sun to dry out completely, then segregated from other yard waste to decompose.
For places where digging is not practical, treating the stumps with an herbicide solution is effective for killing off that clump. Since Japanese honeysuckle roots at multiple points along the vine, treating the cut ends is only effective up to the nearest set of roots. Spraying the foliage with herbicides labeled for use on Japanese honeysuckle is effective whenever it is actively growing. Care must be taken to avoid spraying onto the foliage of desired plants.
This shows the stems, leaves and flowers of mature Japanese stiltgrass.
3. Japanese Stiltgrass
(Microstegium vimineum)
Where you’ll see it: From Texas to Massachusetts and south to Florida
Where it’s invasive: CT, DC, DE, GA, IL, IN, KY, MA, MD, NC, NH, NJ, NY, PA, SC, TN, VA, WI and WV
Why it’s a problem: Japanese stiltgrass spreads aggressively by seeds in open, moist woodlands, on disturbed soils and in lawns where the turf is thin. Its dense growth suppresses other vegetation, and, since animals do not graze on it, it puts more pressure on native and other plant communities. Deer are known to use dense stands of it as bedding. Its seeds stick to the deer’s coat, thus spreading it further into woodlands, particularly along deer paths. Left on its own, stiltgrass can completely engulf an area, obscuring all other plants under 4 feet tall. It found its way into North America as seeds mixed in with the dried grass used as packing material for many items imported from Asia.
How to spot it: Japanese stiltgrass is an annual that grows 1 foot to 4 feet tall in a single season. It germinates when soil temperatures begin to rise, typically in March in the Mid-Atlantic states. It grows and spreads by runners, putting out stems and shallow roots at each node. It has a bamboo-like appearance with several narrowly oblong leaves coming off the vertical stem. It can be distinguished from other grasses by a silvery midvein on each of these leaves.
How to get rid of it: Depending on location and growing conditions, Japanese stiltgrass begins blooming in late July through early September. It puts on a growth spurt, quickly growing from 1 foot to 4 feet in a couple of weeks. The key to controlling its spread is to prevent it from setting and spreading seeds. Pulling out the entire plant just as blooming begins and before seeds begin to ripen will reduce the quantity of seeds released. Since it is an annual, leaving some root fragments in the soil will not be a problem. Pulled plants can be left to dry out and die in the sun. If no seeds have formed, these dead plants can be composted, but I usually use a segregated pile where I can watch for any seed germination. Later in the season, when seed production begins, pulled plants should be burned or bagged and put in the landfill.
Mowing plants in the lawn will remove the primary flowers; however Japanese stiltgrass also has secondary flowers contained within the base of the stem. These are called cleistogamous flowers. They don’t open. Instead, they self-pollinate to produce a small crop of seeds. So even though plants are kept short, a seed bank will be maintained in the lawn. One suggestion for dealing with stiltgrass in lawns is to refrain from mowing while the growth spurt is going on in July and August. In September, cut it very low to get at these lower-stem flowers. This also saps the energy reserve of the stiltgrass, making it harder for it to do a late-season rebloom.
Chemical control of stiltgrass can be achieved using nonselective herbicides, but these will kill all vegetation contacted, so great care must be taken when using them. In lawns, a pre-emergent herbicide can be used to prevent germination and growth in early spring.
As with crabgrass, the most effective way to keep this weed out of the lawn is to maintain a thick, healthy turf. By overseeding and fertilizing in early fall, you have the best chance of getting turf established without feeding the competing weeds. Allowing the lawn to grow taller is also helpful in shading the soil and excluding weeds.
Since Japanese stiltgrass can build up a significant seed bank in the soil, it may take five to seven years to fully clear it out.
3. Japanese Stiltgrass
(Microstegium vimineum)
Where you’ll see it: From Texas to Massachusetts and south to Florida
Where it’s invasive: CT, DC, DE, GA, IL, IN, KY, MA, MD, NC, NH, NJ, NY, PA, SC, TN, VA, WI and WV
Why it’s a problem: Japanese stiltgrass spreads aggressively by seeds in open, moist woodlands, on disturbed soils and in lawns where the turf is thin. Its dense growth suppresses other vegetation, and, since animals do not graze on it, it puts more pressure on native and other plant communities. Deer are known to use dense stands of it as bedding. Its seeds stick to the deer’s coat, thus spreading it further into woodlands, particularly along deer paths. Left on its own, stiltgrass can completely engulf an area, obscuring all other plants under 4 feet tall. It found its way into North America as seeds mixed in with the dried grass used as packing material for many items imported from Asia.
How to spot it: Japanese stiltgrass is an annual that grows 1 foot to 4 feet tall in a single season. It germinates when soil temperatures begin to rise, typically in March in the Mid-Atlantic states. It grows and spreads by runners, putting out stems and shallow roots at each node. It has a bamboo-like appearance with several narrowly oblong leaves coming off the vertical stem. It can be distinguished from other grasses by a silvery midvein on each of these leaves.
How to get rid of it: Depending on location and growing conditions, Japanese stiltgrass begins blooming in late July through early September. It puts on a growth spurt, quickly growing from 1 foot to 4 feet in a couple of weeks. The key to controlling its spread is to prevent it from setting and spreading seeds. Pulling out the entire plant just as blooming begins and before seeds begin to ripen will reduce the quantity of seeds released. Since it is an annual, leaving some root fragments in the soil will not be a problem. Pulled plants can be left to dry out and die in the sun. If no seeds have formed, these dead plants can be composted, but I usually use a segregated pile where I can watch for any seed germination. Later in the season, when seed production begins, pulled plants should be burned or bagged and put in the landfill.
Mowing plants in the lawn will remove the primary flowers; however Japanese stiltgrass also has secondary flowers contained within the base of the stem. These are called cleistogamous flowers. They don’t open. Instead, they self-pollinate to produce a small crop of seeds. So even though plants are kept short, a seed bank will be maintained in the lawn. One suggestion for dealing with stiltgrass in lawns is to refrain from mowing while the growth spurt is going on in July and August. In September, cut it very low to get at these lower-stem flowers. This also saps the energy reserve of the stiltgrass, making it harder for it to do a late-season rebloom.
Chemical control of stiltgrass can be achieved using nonselective herbicides, but these will kill all vegetation contacted, so great care must be taken when using them. In lawns, a pre-emergent herbicide can be used to prevent germination and growth in early spring.
As with crabgrass, the most effective way to keep this weed out of the lawn is to maintain a thick, healthy turf. By overseeding and fertilizing in early fall, you have the best chance of getting turf established without feeding the competing weeds. Allowing the lawn to grow taller is also helpful in shading the soil and excluding weeds.
Since Japanese stiltgrass can build up a significant seed bank in the soil, it may take five to seven years to fully clear it out.
Photo by Katja Schulz
Close examination of the stems and petioles reveals the curved thorns that help mile-a-minute weed climb over other plants.
4. Mile-a-Minute Weed
(Persicaria perfoliata)
Where you’ll see it: Massachusetts to North Carolina and west to Ohio as well as Oregon
Where it’s invasive: AL, CT, DC, DE, MA, MD, NC, NJ, OH, PA, SC, TN, VA, WI and WV
Mile-a-minute weed, also known as Asiatic tearthumb, is a rapidly growing annual vine that is found on disturbed sites like roadsides, ditches, orchards and home landscapes. It will grow well in moist, well-drained soils in part to full sun. Under favorable conditions, it will grow 6 inches in a day. Mile-a-minute weed was introduced to the U.S. from seeds in imported nursery stock from Asia between the late 1930s and 1946.
Why it’s a problem: It grows up and over other plants, covering the tops and shading out light. Visually, it robs the landscape of definition.
How to spot it: Mile-a-minute weed can be recognized by its distinct triangular leaves and the small, sharp, reflexed (backward-curving) thorns that line the vine and petioles. There is a small ring of leaf tissue surrounding where the leaf joins the stem, which is the reason for the name perfoliata. Small white flowers are found in the leaf axils in midsummer. These are followed by blue berrylike fruits. The seeds ripen in early fall. Seeds are dispersed by ants, birds and other wildlife, as well as along waterways, where the seeds can float for seven to nine days.
How to get rid of it: Hand-pulling is quite effective for small infestations. The vines are fairly tough, but the root system is weak. Careful pulling of the vine up and away from its support will often uproot the entire vine. Pulling earlier in the summer is most effective — the vines are smaller, and the thorns have not had a chance to harden. It is important to wear gloves and long sleeves when pulling to minimize scratching. Also, pulling should be done before the seeds have a chance to ripen in late summer or early fall. Vines without seeds can be balled up and left in the sun to dry. For infestations that are in open areas, weed-whacking or mowing early in the season can reduce seed production.
Both pre- and post-emergent herbicides are effective at killing mile-a-minute weed. Application of spray herbicides is difficult since the weed tends to grow on top of desirable vegetation and landscape plants. Although useful for knocking down a particularly bad infestation, the use of herbicides is not a viable long-term solution.
More effective is the mile-a-minute weevil (Rhinoncomimus latipes), which was approved for introduction into the U.S. from China in 2004. These insects feed selectively on the leaves and stems of mile-a-minute weed. Weevils have been released at many sites in the Mid-Atlantic region, and reduction in the density of mile-a-minute weed has been observed. In some of these areas, mile-a-minute weed infestations have collapsed over one to two years. The presence of these weevils is evidenced by seeing many holes in the leaves, almost to the point of skeletonization. If I see evidence of weevil activity, I usually try to leave any vines I pull nearby so that the weevils will hang around to find their way back for more mile-a-minute.
Seeds can remain viable for up to six years, so continued monitoring is needed to keep a problem from flaring up again. With the weevil help, serious mile-a-minute weed infestations may become more manageable.
4. Mile-a-Minute Weed
(Persicaria perfoliata)
Where you’ll see it: Massachusetts to North Carolina and west to Ohio as well as Oregon
Where it’s invasive: AL, CT, DC, DE, MA, MD, NC, NJ, OH, PA, SC, TN, VA, WI and WV
Mile-a-minute weed, also known as Asiatic tearthumb, is a rapidly growing annual vine that is found on disturbed sites like roadsides, ditches, orchards and home landscapes. It will grow well in moist, well-drained soils in part to full sun. Under favorable conditions, it will grow 6 inches in a day. Mile-a-minute weed was introduced to the U.S. from seeds in imported nursery stock from Asia between the late 1930s and 1946.
Why it’s a problem: It grows up and over other plants, covering the tops and shading out light. Visually, it robs the landscape of definition.
How to spot it: Mile-a-minute weed can be recognized by its distinct triangular leaves and the small, sharp, reflexed (backward-curving) thorns that line the vine and petioles. There is a small ring of leaf tissue surrounding where the leaf joins the stem, which is the reason for the name perfoliata. Small white flowers are found in the leaf axils in midsummer. These are followed by blue berrylike fruits. The seeds ripen in early fall. Seeds are dispersed by ants, birds and other wildlife, as well as along waterways, where the seeds can float for seven to nine days.
How to get rid of it: Hand-pulling is quite effective for small infestations. The vines are fairly tough, but the root system is weak. Careful pulling of the vine up and away from its support will often uproot the entire vine. Pulling earlier in the summer is most effective — the vines are smaller, and the thorns have not had a chance to harden. It is important to wear gloves and long sleeves when pulling to minimize scratching. Also, pulling should be done before the seeds have a chance to ripen in late summer or early fall. Vines without seeds can be balled up and left in the sun to dry. For infestations that are in open areas, weed-whacking or mowing early in the season can reduce seed production.
Both pre- and post-emergent herbicides are effective at killing mile-a-minute weed. Application of spray herbicides is difficult since the weed tends to grow on top of desirable vegetation and landscape plants. Although useful for knocking down a particularly bad infestation, the use of herbicides is not a viable long-term solution.
More effective is the mile-a-minute weevil (Rhinoncomimus latipes), which was approved for introduction into the U.S. from China in 2004. These insects feed selectively on the leaves and stems of mile-a-minute weed. Weevils have been released at many sites in the Mid-Atlantic region, and reduction in the density of mile-a-minute weed has been observed. In some of these areas, mile-a-minute weed infestations have collapsed over one to two years. The presence of these weevils is evidenced by seeing many holes in the leaves, almost to the point of skeletonization. If I see evidence of weevil activity, I usually try to leave any vines I pull nearby so that the weevils will hang around to find their way back for more mile-a-minute.
Seeds can remain viable for up to six years, so continued monitoring is needed to keep a problem from flaring up again. With the weevil help, serious mile-a-minute weed infestations may become more manageable.
Here is a small section of creeping Charlie as it appears in wintertime; note the slight bronzing of the leaves.
Photo by Donald Hobern
5. Creeping Charlie
(Glechoma hederacea)
Where you’ll see it: All states in the U.S. except AZ, HI, NM and NV
Where it’s invasive: CT, DC, IL, IN, KY, MD, MI, NC, NH, NJ, OR, PA, TN, VA, WI and WV
Other names for the common weedy plant are gill-over-the-ground and ground ivy. This European member of the mint family likes moist, shady to partly sunny locations with fertile soils. It will invade shady lawns if the turf is thin and the soil is cool and moist. It can also encroach into woodlands, forest edges, gardens and other disturbed areas.
Why it’s a problem: In these areas, it can form dense evergreen mats of foliage that crowd out other plants — native species are particularly affected. In large doses, it is toxic to livestock; however, most animals will avoid eating it. The spread of this species is primarily by vegetative growth.
How to spot it: Creeping Charlie is a square-stemmed, ground-hugging vine that puts down additional roots at leaf nodes all along the stem. Each node bears a pair of roundish or kidney-shaped leaves with scalloped edges, typically ⅜ to 1 inch across. The leaves are deeply veined. Blooming begins in early spring and continues into summer with lavender flowers. The five-lobed, tubular blooms appear in clusters of two or three in the leaf axils of the upright flowering stems. The seeds mature in early-to-mid summer.
How to get rid of it: For small infestations and in garden beds, pulling out the vines may be most effective. This is easiest to do when the soil is moist. Care should be taken to remove all the rooted nodes to prevent these plants from getting reestablished. Since these vines can reroot easily, drying them in the sun completely to kill them or bagging and putting them in the landfill are among the best means of disposal.
There are several commercial herbicides that are effective for treating creeping Charlie. In general, treatments applied in fall are most effective, followed by springtime, when it is in flower. Treating in summer has shown the poorest results. Since these herbicides will also kill other broad leaf plants, desirable plants like clovers and violets will be affected. Using targeted application in the fall will help minimize collateral damage.
Using cultural practices that discourage growth of creeping Charlie are preferable to relying on herbicides for control. In a lawn, this includes using the proper turf species for a given location, proper fertilization (no more or less than needed), breaking up compacted soils (aeration), improving exposure to light and avoiding overwatering. Mowing at a height of 3 inches or more will also help with establishing a thick turf. An overview of control methods for creeping Charlie can be found in the Plant Guide put out by the USDA.
Creeping Charlie also is poorly tolerant of salt and acidic soils. In planting beds, thorough weeding and mulching to remove the infestation, and then adding a buffer zone of mulch or a dense planting around the bed will help block it from climbing back into the garden. A rust fungus (Puccinia glechomatis) has been found that severely damages creeping Charlie. This holds some promise as a biological control.
5. Creeping Charlie
(Glechoma hederacea)
Where you’ll see it: All states in the U.S. except AZ, HI, NM and NV
Where it’s invasive: CT, DC, IL, IN, KY, MD, MI, NC, NH, NJ, OR, PA, TN, VA, WI and WV
Other names for the common weedy plant are gill-over-the-ground and ground ivy. This European member of the mint family likes moist, shady to partly sunny locations with fertile soils. It will invade shady lawns if the turf is thin and the soil is cool and moist. It can also encroach into woodlands, forest edges, gardens and other disturbed areas.
Why it’s a problem: In these areas, it can form dense evergreen mats of foliage that crowd out other plants — native species are particularly affected. In large doses, it is toxic to livestock; however, most animals will avoid eating it. The spread of this species is primarily by vegetative growth.
How to spot it: Creeping Charlie is a square-stemmed, ground-hugging vine that puts down additional roots at leaf nodes all along the stem. Each node bears a pair of roundish or kidney-shaped leaves with scalloped edges, typically ⅜ to 1 inch across. The leaves are deeply veined. Blooming begins in early spring and continues into summer with lavender flowers. The five-lobed, tubular blooms appear in clusters of two or three in the leaf axils of the upright flowering stems. The seeds mature in early-to-mid summer.
How to get rid of it: For small infestations and in garden beds, pulling out the vines may be most effective. This is easiest to do when the soil is moist. Care should be taken to remove all the rooted nodes to prevent these plants from getting reestablished. Since these vines can reroot easily, drying them in the sun completely to kill them or bagging and putting them in the landfill are among the best means of disposal.
There are several commercial herbicides that are effective for treating creeping Charlie. In general, treatments applied in fall are most effective, followed by springtime, when it is in flower. Treating in summer has shown the poorest results. Since these herbicides will also kill other broad leaf plants, desirable plants like clovers and violets will be affected. Using targeted application in the fall will help minimize collateral damage.
Using cultural practices that discourage growth of creeping Charlie are preferable to relying on herbicides for control. In a lawn, this includes using the proper turf species for a given location, proper fertilization (no more or less than needed), breaking up compacted soils (aeration), improving exposure to light and avoiding overwatering. Mowing at a height of 3 inches or more will also help with establishing a thick turf. An overview of control methods for creeping Charlie can be found in the Plant Guide put out by the USDA.
Creeping Charlie also is poorly tolerant of salt and acidic soils. In planting beds, thorough weeding and mulching to remove the infestation, and then adding a buffer zone of mulch or a dense planting around the bed will help block it from climbing back into the garden. A rust fungus (Puccinia glechomatis) has been found that severely damages creeping Charlie. This holds some promise as a biological control.
Here is an area where garlic mustard and Japanese stiltgrass have been removed for a couple of years. Christmas fern (Polystichum acrostichoides), native sedges and Philadelphia fleabane (Erigeron philadelphicus) are reasserting themselves.
General Weed Management Strategies
A general strategy for clearing out an invasion is to concentrate on new invasions first, before a seed reserve is established. These are easier to clean than an established infestation.
Next, take actions to prevent new seeds from being produced — this may just involve removing flowers or severing climbing vines. For perennial invaders, removing or killing most or all of the plant will be necessary.
Finally, deplete the seed bank. This involves removing seedlings and continued monitoring, most likely for a number of years.
Also, when removing weeds, minimize soil disturbance and do not leave soil uncovered. Bare and disturbed soils are just the places where invasive weeds get started. Either put in some new plants or seeds, or cover the area with a thick layer of mulch to prevent a new invasion.
New plants are always coming along and are being used in our landscapes. Although these plants are evaluated for their hardiness and garden suitability, their tendency to escape the garden environment may not have been part of the process. As the people in the garden, we have an opportunity, and the responsibility, to watch for plants escaping and to take steps to bring them back in bounds.
More
Tackle Weeds the Natural Way
How to Find the Right Native Plants for Your Yard
General Weed Management Strategies
A general strategy for clearing out an invasion is to concentrate on new invasions first, before a seed reserve is established. These are easier to clean than an established infestation.
Next, take actions to prevent new seeds from being produced — this may just involve removing flowers or severing climbing vines. For perennial invaders, removing or killing most or all of the plant will be necessary.
Finally, deplete the seed bank. This involves removing seedlings and continued monitoring, most likely for a number of years.
Also, when removing weeds, minimize soil disturbance and do not leave soil uncovered. Bare and disturbed soils are just the places where invasive weeds get started. Either put in some new plants or seeds, or cover the area with a thick layer of mulch to prevent a new invasion.
New plants are always coming along and are being used in our landscapes. Although these plants are evaluated for their hardiness and garden suitability, their tendency to escape the garden environment may not have been part of the process. As the people in the garden, we have an opportunity, and the responsibility, to watch for plants escaping and to take steps to bring them back in bounds.
More
Tackle Weeds the Natural Way
How to Find the Right Native Plants for Your Yard
The following five invasive species are commonly encountered in the Mid-Atlantic region, where I am located, but they are also invasive or are of concern (watch-listed) throughout the country, particularly garlic mustard and Japanese honeysuckle. By recognizing and controlling invasive species in and around our properties, we can help curb the spread of these plants.
The following plants have been listed as invasive in the accompanying regions by the Invasive Plant Atlas, the Mid-Atlantic Exotic Pest Plant Council and the Midwest Invasive Plant Network. You can learn more about invasive plant species in North America at Invasive.org.