15 Invasive Perennials You Don’t Want In Your Garden

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Perennials are a gardener’s friend. We count on these plants to come back every year, thus saving us time, effort, and money. They are also visually stunning, low maintenance, resilient, and diverse. So, I totally understand the urge to have perennials plants in your garden.

However, sadly, not every perennial should be in your garden, as some varieties are invasive. They spread rapidly and outcompete the more desirable flora in your garden.

To help you maintain ecological balance and garden harmony, let’s explore 15 invasive perennials to avoid growing.

15 Invasive Perennials You Don’t Want In Your Garden

Invasive Perennials You Don't Want In Your Garden

Here is a list of invasive plants you should avoid planting in your garden:

1. Japanese Knotweed (Fallopia japonica)

Invasive Perennials You Don't Want In Your Garden

Originally introduced as an ornamental plant, the Japanese Knotweed has become among the most notoriously invasive plants globally. The dense thickets it forms outcompete other vegetation, reducing plant diversity.

The Japanese Knotweed can grow up to 10 feet tall. It spreads through its extensive root system, capable of growing up to 10 feet deep and spreading 23 feet horizontally. These roots are strong enough to grow through building foundations, asphalt, and concrete.

Once established, removing it is challenging.


  • Native shrubs like Red Osier Dogwood and Smooth Hydrangea
  • Clumping bamboo

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2. Purple Loosestrife (Lythrum salicaria)

invasive perennials to avoid

While a gorgeous plant, its beauty belies its invasive nature that threatens wetlands and waterways. Purple loosestrife’s dense growth can alter wetlands’ structure and function by disrupting the water flow, sedimentation patterns, and nutrient cycling.

The dense stands that purple loosestrife forms can kill every plant in its path. This perennial is a prolific seed producer (a single plant can produce up to 2.5 million seeds annually. Many places across North America categorize this plant as invasive, with some even banning it.


  • Blue Vervain
  • Swamp Milkweed
  • Joe-Pye Weed

3. Periwinkle

Invasive garden plants to avoid

As a groundcover, the periwinkle is a fantastic choice because of its lush, evergreen foliage that forms dense mats and charming blue or purple flowers. Moreover, it thrives in shades. This sounds fantastic, doesn’t it? Well, there’s one caveat. This plant is invasive.

Initially, the periwinkle starts as a perfect, well-mannered plant. However, it quickly forms dense mats that outcompete native ground cover and young trees. Common Periwinkle grows 3 to 6 inches tall, while greater periwinkle reaches 6 to 18 inches.


  • Wild Ginger
  • Foamflower
  • Creeping Phlox
  • Barrenwort

4. English Ivy (Hedera helix)

Dangerous invasive plants

The lush trailing foliage of English Ivy is a sight to behold and is great for ground cover and wall coverings. Unfortunately, this perennial forms dense mats that smother the ground and prevent native plants from germinating and growing.

In addition, when English Ivy climbs trees, it can cover the bark and leaves, blocking sunlight and inhibiting photosynthesis, weakening and eventually killing the trees. English Ivy is a formidable invader because it is resilient, tolerates various conditions, and spreads aggressively.


  • Boston Ivy
  • Virginia Creeper
  • Creeping Jenny

5. Lily of the Valley (Convallaria majalis)

invasive perennials you don't want in your garden

This beloved perennial is easy to grow and a sought-after cut flower. Unfortunately, the lily of the valley spreads like wildfire, which is why you should not grow it in your garden. It spreads rapidly underground because of its extensive rhizomatous root system.

Once established, this beautiful perennial can take over your garden by spreading and forming dense colonies. If you must grow it, contain its spread using raised beds or underground barriers


  • Sweet Woodruff
  • Solomon’s Seal
  • Foamflower

6. Japanese Honeysuckle

Invasive perennials to avoid

The invasive nature and ecological impact of the Japanese Honeysuckle overshadow its attractive features, such as its tubular, fragrant flowers, twining vines, and green, oval-shaped leaves. This perennial rapidly covers large areas with vines that grow quickly, often several feet in a single growing season.

Japanese Honeysuckle endangers other plants, trees, and shrubs by climbing and enveloping them. It can also crush other vegetation with its weight and deprive them of nutrients and light with its dense mats and arbors.


  • Trumpet Honeysuckle
  • Coral Honeysuckle
  • Crossvine

7. Sweet Autumn Clematis (Clematis terniflora)

Invasive garden plants to avoid

If you love clematis, you have multiple non-invasive species and cultivars, such as Clematis’ Jackmanii’ and Clematis integrifolia, to grow in your garden. However, avoid sweet autumn clematis.

Its vigorous, twining vines can climb up to 30 feet high. Autumn clematis will rapidly spread over your trees, shrubs, and fences if you let it. Moreover, it can colonize new areas rapidly through prolific seed production and effective wind dispersal.

Avoid Clematis Vitalba as well because it is invasive in several places, including North America.


  • Climbing Hydrangea
  • American Wisteria
  • Crossvine

8. Carpet Bugleweed (Ajuga reptans)

Invasive garden plants

A single carpet bugleweed plant looks charming and harmless, but don’t let its attractiveness and demeanour fool you. This perennial groundcover spreads aggressively through its stolons and swiftly develops a dense mat that can quickly take over your garden.

Carpet bugleweed is especially problematic in warmer regions that don’t get winter frost. Many complain that it tends to grow into the lawn, thus killing the grass. Therefore, avoid it if you don’t want a garden or yard full of carpet bugleweeds.


  • Creeping Thyme
  • Creeping Jenny
  • Creeping Phlox

9. Pampas Grass (Cortaderia selloana)

invasive plants to avoid in your garden

This ornamental grass is undeniably beautiful and adds a dramatic touch to any landscape. This, however, doesn’t mean you should have it in your garden. Pampas Grass is highly invasive in many regions as it spreads rapidly.

It self-seeds freely through wind-dispersed seeds and rapidly grows into a huge clump. Due to this, it can effortlessly take over your garden and crowd other plants if you leave it unchecked. Trying to dig out pampas grass isn’t a cakewalk, especially established ones, due to their enormous root system.


  • Pink Muhly Grass
  • Fountain Grass
  • Feather Reed Grass

10. Common Tansy (Tanacetum vulgare)

pretty invasive flowers

Historically, this perennial herbaceous plant holds great value for its medicinal properties but is now widely regarded as a noxious weed due to its aggressive growth habit. This persistent weed spreads rapidly through seeds and creeping rhizomes, forming dense stands that choke out other plants.

The dense colonies that common tansy form can shade out native plants and impede access to resources. The wind also disperses its tiny, numerous seeds, allowing new common tansy plants to colonize new spaces.


  • Yarrow
  • Bee Balm
  • Joe Pye Weed

11. Bishop’s Weed (Aegopodium podagraria)

Types of Invasive Plants You Should Avoid

Despite its decorative appeal, bishop’s weed isn’t a plant you want in your garden as it grows vigorously and is challenging to eradicate. It can quickly take over your landscapes, from the garden to lawns. Furthermore, its rhizomes can regenerate from small fragments, so this plant can return even after extensive weeding.

Bishop’s weed will also compete aggressively with other plants for resources, negatively impacting your desirable plants. You can weaken it over time through repeated mowing or suppress its growth through mulching.


  • Lilyturf
  • Wild ginger
  • Foamflower

12. Yellow Toadflax (Linaria vulgaris)

invasive plants to avoid in your garden

This Eurasia native perennial is problematic in various habitats such as pastures, grasslands, roadsides, and disturbed areas. It persistently invades areas thanks to its numerous tiny seeds dispersed over long distances by wind, water, and human activities. Yellow Toadflax is also difficult to eradicate.

Its seeds can remain viable in the soil for several years. Furthermore, it diminishes biodiversity by forming monocultures and displacing native plants. Also, the chemicals it secretes into the soil give it a competitive advantage over neighboring plants.


  • Columbine
  • Coreopsis
  • Black-Eyed Susan

13. Chinese Wisteria (Wisteria sinensis)

invasive plants to avoid in your garden

There are many cultivars and varieties of Wisteria, and while not all of them are invasive, Chinese Wisteria is definitely invasive. This exotic plant may have captured the hearts of many due to its cascading clusters of fragrant, lavender-hued blooms and twisting, vine-like stems.

But this vigorous climber can grow 30 meters high or more, smothering and shading out smaller vegetation. It also produces copious quantities of seeds dispersed by different means. Furthermore, the Chinese Wisteria can girdle other trees and shrunks.


  • American Wisteria
  • Clematis
  • Honeysuckle

14. Tree of Heaven (Ailanthus altissima)

Invasive Plants You Should Avoid

Tree of Heaven’s most defining feature is its astonishing growth rate. Capable of growing to 80 feet high and diameters of 6 feet, this tree can quickly take over your garden. It is also not picky about where it grows; it thrives on roadsides, vacant lots, and even sidewalk cracks.

It displaces native plants by forming dense thickets, and its thick canopy can overshadow and suppress other vegetation. Moreover, the Tree of Heaven can damage your infrastructure, including the sidewalk and foundations.


  • Red Maple
  • Tulip Tree
  • Serviceberry

15. Japanese Barberry (Berberis thunbergii)

invasive perennials
Japanese barberry


This perennial shrub is renowned for its foliage, bright red berries, and thorny branches, but its invasive nature can threaten your garden. Japanese Barberry grows and spreads aggressively through its seeds and vegetatively. For instance, animals like birds eat the berries and disperse the seeds over vast areas.

Additionally, the plant can spread through root suckers, creating dense thickets. The Japanese Barberry’s dense thickets allow it to displace other plants and reduce your garden’s biodiversity.


  • Bigleaf Hydrangea
  • Ninebark
  • Winterberry Holly
  • Chokeberry
Final Remarks

All the plants in this list appeal differently, from their foliage, color, structure, and fabulous blooms to fruit production. However, they share one thing in common that makes them undesirable for gardens: their invasiveness. For this reason, you are better off choosing their non-invasive alternatives, as this will save you a lot of trouble in the long run.

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