11 Invasive Plants You Should Never Buy At The Garden Center

All gardeners are susceptible to impulse plant purchases now and then. Wandering through the garden center can be such a thrill, with so many beautiful plants on display that will add color and interest to the yard.

However, hidden among the many star-performing plants are a few silent invaders that should be avoided at all costs. These invasive plants may look harmless and even possess appealing qualities. Yet, they can quickly get out of control, smothering other plants and threatening wildlife habitats.

What's more, invasive plant removal can be almost impossible – meaning constant work to chop down foliage, remove dead flowers, and pull up roots.

Unfortunately, not all garden centers are vigilant about keeping these plants out of their stock.

In this article, we expose the potential risks posed by some of the most commonly bought invasive plants and the detrimental effects they can have on native flora and fauna. From fast-spreading ground covers to vigorous climbers and unruly shrubs, these plants should not be on the shopping list of most gardeners.

But don't worry, we won't leave you empty-handed. We also offer alternative non-invasive suggestions, ensuring you make sustainable choices for your landscape.

1. Chameleon Plant

The chameleon plant (Houttuynia cordata) is a fast-growing perennial ground cover that can be grown in USDA planting zones 5-11. It features attractive, colorful foliage in shades of pink, green, and yellow, and is often planted in areas of difficult soil that might otherwise remain bare.

However, think twice before you pick one up at the garden center, as killing chameleon plants is almost impossible. Its roots spread vigorously through underground rhizomes that are fragile and break easily. Even when you think you have pulled it all up, it will resprout from the root system.

To add to its faults, the plant emits a smell similar to diesel fuel, so should never be planted near patios and seating areas.

While you could consider confining the chameleon plant to a container, there are some lovely non-invasive alternatives to choose from. Look to plants from the coral bells or foamflower families. They are available in many colors and form small clumps of foliage that stay compact to provide color and interest to the front of a border. They can also be used as a ground cover.

2. Lily of the Valley

With its pretty bell-shaped white flowers and short habit, lily of the valley (Convallaria majalis) may look innocent but it can spread aggressively through rhizomes and self-seeding, negatively affecting local plant populations.

This woodland native is commonly available in garden centers in some states, while others list it as an invasive plant because of its tendency to quickly form large colonies. It thrives in partial shade and moist soil in USDA zones 2-9.

Though its sweet fragrance makes it an alluring choice, all parts of the plant are highly poisonous. The toxicity of lily of the valley makes it unsuitable for properties with children and pets.

If your eyes are drawn to the attractive white blooms, good alternatives would be snowdrops, white bellflower, or white balloon flower. All are low-growing and can provide spring or summer blooms.

Where present, lily of the valley control involves regular deadheading and containing it to areas where it can not spread and take over other plants.

3. Butterfly Bush

Butterfly bush (Buddleia) is a popular perennial shrub that helps to attract butterflies and other beneficial pollinators to gardens in USDA zones 5-10. Its attractive blooms are available in various colors to complement any landscape.

However, left unchecked, the wild species, Buddleia davidii, can self-seed and invade open spaces, crowding out native plants. This is problematic even in riverbanks, open fields, and reforested areas, where the bushes form thick, shrubby thickets that prevent the development of other wild plants.

Controlling invasive butterfly bushes is no easy task, and starts with consistent deadheading of flowers.

The butterfly bush is considered invasive in many states, as well as in England and New Zealand. Some states, like Oregon, have even banned sales of the plant.

But if you are a fan of buddleia, do not despair, as growers are coming to the rescue. They have developed sterile, compact butterfly bush varieties that make an attractive addition to the garden. Look for the trademarked series called Lo & Behold or Flutterby.

4. Callery Pear

Once a popular urban landscaping tree in USDA zones 5-9, the ornamental Callery pear (Pyrus calleryana) – also known as Bradford pear – has an invasive nature, bitter fruit, and an offensive smell often compared to rotting fish or vomit.

Callery pear's best-known cultivars are 'Bradford', 'Cleveland Select', and 'Chanticleer'. Initially, these trees were believed to be sterile, and unable to reproduce by seed. However, as cultivars cross-pollinated, viable seeds were produced and the tree spread within local landscapes and other natural areas.

The resultant trees have large thorns which can injure livestock. As the trees spread, they also crowd out native species needed by local wildlife.

Callery pear has become so invasive that some states have made it illegal to grow, sell, and plant these trees.

Fortunately, there are some lovely Bradford pear alternatives that will make equally stunning – and less smelly – landscaping features. Consider serviceberry, Eastern redbud, or flowering dogwood.

5. Running Bamboo

Bamboo is known for its versatility and quick growth habit, filling out an attractive privacy hedge at a rapid pace.

But once planted this fast grower can become incredibly invasive due to its complex root system that can spread and grow underground, sending out runners up to 100 feet (31m) away. This means your new bamboo patch may suddenly spread to your neighbor’s landscape, then their neighbor's, and so on. Once established, killing bamboo is extremely difficult.

The type of bamboo in question is running bamboo (Phyllostachys/Pleioblastus). Depending on the species, the plants thrive in USDA zones 4-10, where they can easily degrade natural areas and displace native plants.

On the other hand, clumping bamboo (Fargesia) grows just as the name suggests: in a clump. It is fairly well-mannered and its root system circles the parent plant, with a steady but slow spread. This type would be recommended as a well-behaved bamboo in the landscape. Be certain you are buying clumping bamboo before investing.

If you're after the look of bamboo but want to keep this invasive plant out of your landscape, try any of the tall and upright ornamental grasses available at the garden center. Or, if a privacy hedge is what you covet, arborvitae, cedar, and juniper would all be good choices.

6. Burning Bush

Burning bush (Euonymus alatus) is an extremely popular ornamental shrub with a vibrant red fall color. It's commonly found in residential landscapes and commercial plantings within USDA zones 4-8.

In some areas, however, burning bush is now considered a threat because of its ability to invade natural areas and outcompete native plant species. Birds eat the berries and inadvertently plant the seeds in the soil, while even dropped seeds can sprout in rich soils.

The shrub has become widespread along the East Coast and much of the Midwest. Some states, including Massachusetts and New Hampshire, have prohibited its sale.

Burning bush control in the garden is not too difficult, and relies on removing seedlings. However, the seeds can easily spread to the surrounding landscape.

Luckily, there are plenty of great alternatives that provide similar color and multi-season interest in the landscape. Blueberry bushes, itea sweetspire, and oakleaf hydrangeas showcase bright red fall color, along with attractive flowers. Red twig dogwood is another option for fall foliage color and continued interest through the winter with its bright stems.

7. Japanese barberry

Barberry is a common shrub selected primarily for its pretty purple or red foliage that contrasts well in the landscape. Recently this shrub has escaped its original confines and certain species – particularly Japanese barberry (Berberis thunbergii) – are now considered highly invasive in some areas, especially in eastern North America.

The shrubs are hardy and thrive in full sun to deep shade in USDA zones 4-8. While beautiful to look at, Japanese barberry has needle-sharp thorns that can rip the skin.

To make matters worse, Japanese barberry has been shown to have a role in the spread of Lyme disease. A study found that the larger the number of barberries in an area, the higher the incidence of Lyme disease-carrying ticks. So, this aggressive plant not only affects our environment but our health too.

Japanese barberry control takes persistence and involves hand pulling or digging early in the season, before the seed drops. Birds will eat the fruits of the plant and distribute the seed, forming impenetrable thickets that shade out wildflowers and other native plants.

Thankfully, there are barberry substitutes with similar red or purple foliage colors. These include varieties of weigela and ninebark.

8. Scotch Broom

With its cheerful yellow flowers, Scotch broom (Cytisus scoparius) may catch your eye at the garden center.

However, though it is considered a short-lived plant, it can spread aggressively and choke out native plants. Wildlife find the shrub unpleasant and may be driven from a habitat overtaken by this shrub. Worse still, it emits a toxic chemical in the soil that may prohibit other plants from growing.

Scotch broom grows in USDA zones 5-8. It has proved to be less aggressive in the East than in the West, where it is listed as an invasive weed in several states including California, Washington, and Oregon. A mature plant can produce upwards of 12,000 seeds per year.

Once established, plants are difficult to kill. Scotch broom control involves continual shearing and root removal until the plant fails to return. Unfortunately, the hard-coated seeds remain viable for as long as 80 years.

The good news is that there are plenty of pretty yellow flowering plants for your landscape besides the scotch broom. Consider the yellow wild indigo, also known as baptisia, or the eye-catching yellow-blooming Exbury azaleas.

9. English Ivy

Many gardeners use English ivy (Hedera helix) to cover the walls of a building or sprawl along the ground in a shady area. However, this non-native plant is now considered invasive in many states and should be avoided.

Grown in USDA zones 5-11, English ivy's aggressive foliage can smother native vegetation and cause extensive damage to natural areas, walls, and structures. The plant reproduces quickly by both runners and seeds dispersed by birds.

It is difficult to kill English ivy, so the best course of action is to avoid planting it in the first place.

However, if you simply can't resist the old-world charms of English ivy, then you can safely grow ivy houseplants indoors.

Alternatively, plenty of English ivy alternatives offer wall and ground cover in a non-aggressive manner. Consider the climbing hydrangea with its woody base and glossy green leaves that showcase large white lacecap flowers. Plus, it grows slowly and is easy to maintain as it grows.

10. Japanese Honeysuckle

A climbing vine covered with sweetly scented flowers in spring, Japanese honeysuckle (Lonicera japonica) is an invasive weed that can take over gardens in USDA zones 4-11. It suppresses the growth of native plants and ultimately damages the environment around it.

Japanese honeysuckle is easily spread to other areas by birds, who love to feast on its berries. It is considered a noxious weed in many New England states, a top invasive plant in both Georgia and Florida, and is now listed as a severe threat in Kentucky, Tennessee, and South Carolina.

Luckily, freezing winter temperatures keep the vines in check in cold, northern climates, but in southern and Midwestern states, managing honeysuckle is a never-ending problem.

Do not let Japanese honeysuckle tempt you with its sweet, intoxicating fragrance – opt for a non-invasive shrub variety instead. Many types of honeysuckle will prove welcome additions to the garden if chosen carefully.

11. Mexican Evening Primrose

Mexican evening primrose (Oenothera speciosa) may draw you in with its delicate pink flowers, but this plant can quickly get out of hand. While this plant is not technically considered invasive, there have been enough complaints against it to warrant caution. It thrives in USDA zones 4-9.

A cousin to the yellow evening primrose, Mexican evening primrose has been known to outcompete other plants in a flower bed and even take over grassy lawns. The plants can grow in less-than-ideal conditions, including in rocky and dry landscapes. It spreads by both seed and strong runners.

Mexican primrose control is extremely difficult as even if the plant is pulled or disturbed in any way, new growth will continue from the root system.

It is possible to grow the plants in containers if you do not let the plant go to seed. However, dianthus, hardy geranium, and creeping phlox are all terrific low-growing alternatives to this pink flowering ground cover.

A Note On Invasive Plants

Bear in mind some plants may be considered invasive in one area and not another. The term invasive is relative and dependent on your region and geographical climate. State extension services are a great place to start with research on your region’s invasive plants.

Even if they are not considered invasive by a government agency, many fellow gardeners have an unfavourable experience with these particular plant species.

We hope this information has shed some light on the potential danger of certain plant species and that it helps you to make more informed decisions for your garden space.