Invasive Plants to Watch Out For in the Garden

Invasive Plants to Watch Out For

Pretty flowers are good to have around, but it’s quite possible that some of the denizens in your garden happen to be evil flowers. They may masquerade as common versions of prettier flowers, but be warned – they sow destruction whenever they spread. Like a seedy neighbor, they creep unwarranted into your garden landscape, imposing their will onto the locals, strangling native habitats and wreaking havoc to the infrastructure. While various definitions disagree on the exact semantics, it can generally be said that any nonnative plant that is a nuisance to eradicate can be considered an invasive. 

Each region will have invasives specific to that region, but there are some common culprits that have become naturalized and problematic throughout large swaths of the country. In colder climates, these invasive plants will not pose as much a threat, as the cold weather suppresses the migration of seeds, but in more temperate climates, they have a tendency to wander and flourish all too well. Below is a list of invasive plants to watch out for and prevent their spread. 

1. Autumn Olives  

Autumn olive and Russian olive, two different species often conflated due to similar growth habits, were originally introduced to combat soil erosion. This backfired when it began spreading like wildfire along riparian zones, roadsides, and meadows. Russian olive bears oblong, silvery fruit that turns a burnt color; by contrast, the fruit of autumn olive is red-colored and rounder, dotted with silver scales. Seeds are primarily dispersed by birds that eat their fruits. Both are nitrogen-fixers, housing nitrogen fixing bacteria in the surrounding soil, which can seem beneficial at first. But over time, in large numbers, they alter the soil chemistry and become disruptive to local communities.  

Control: Cut-stump treatment.

2. Bastard Cabbage   

The bane of Texas, bastard cabbage may be the worst neighbor on this side of the Rio Grande. On the outside, it retains an innocuous veneer: wispy tendrils of yellow flowers. But this bastard is quick to lay siege, ousting native wildflowers and transforming it into a monoculture of yellow overnight. Many fields claimed by bastard cabbage once used to be striking fields of bluebonnets – a grim indication of what’s to come. 

Control: Tender plants can be pulled or foraged; reseeding areas where bastard cabbage used to thrive. 

3. Honeysuckle                 

They may smell good, but they are swift to declare war. Many varieties of honeysuckle, including amur honeysuckle and Japanese honeysuckle, ran rampant, forming impenetrable masses until the land is choked solid. A quick way to check if the honeysuckle in your area is invasive is to check its pith, or the woody center. In native honeysuckles, the pith is solid, whereas in invasiveness, it is hollow. Gardeners who savor the honeysuckle’s heady fragrance can plant non-invasive natives instead. 

Control: Cut it close to the root.

4. Japanese Barberry                     

An intractable and thorny plant, the Japanese Barberry is a common ornamental that has no sense of personal space. Like most comic book villains, it is banned in public spaces (in New York at least), is the textbook case for several problematic behaviors, and revels in aggrandizing land meant for others. Equipped with soil pH altering abilities, it viciously crowds out natives, forming pernicious, impenetrable thickets that have been identified as a vector for back-legged ticks. 

Control: Falls into the ‘kill with fire’ category; propane torches are excellent in combating it. Repeated mowing with professional equipment can limit its spread.

5. Tree-of-Heaven 

Possibly one of the most flagrant misnomers, the tree-of-heaven is a blight on the land and is devilishly hard to eradicate. Its leaves emit a fetid odor reminiscent of cat pee, and to make matters worse, is host to the destructive spotted lanternfly. It can look similar to other native tree species, so be sure to correctly identify it before you rip it out of your yard. 

Control: Pulling out seedlings can kill it in its initial stages.

6. Lesser Celandine    

Lesser celandine is a pretty but invasive ‘spring ephemeral’ that wipes out other spring ephemerals with its vast stockpile of underground tubers. Lesser celandine bears many similarities with marsh marigold, but it can be differentiated by its larger number of petals (7 – 12 v. 5 – 9) and three green sepals underneath. 

Control: Its bloom time makes removal a time-sensitive endeavor – small infestations can be controlled through hand-digging.

 

7. Bindweed 

Bindweed is an attractive weed, and indeed, it’s viewed as an improvement to the festering ugliness of parking lots. It may be more attractive than some of the common eyesores, such as spurge, but quickly extends its line of aggression to ravines and residential areas. Bindweed is a problematic agricultural weed that causes millions of dollars of agricultural damage every year.

Control: Pulling and pouring boiling water on it can help manage it.

8.  Butterfly Bush  

Butterfly bush (Buddleja davidii) is an eye-catching plant that’s wound its way to many gardens due to its ability to attract butterflies. Yet, depending on where you live and what variety you have, butterfly bush can be terribly invasive. Proponents of native planting caution against buying any variety regardless and suggest replacing it with beneficial natives. 

Control: Prune it to the base and then dig it out. 

9. English Ivy  

English ivy is a creeping vine that is often strung decoratively around old brick buildings, spreading via runners that exude a glue-like substance as it climbs. However, its status as an aggressive invader that outcompetes native species and strangles canopies makes it a threat. There are several methods of removal, including renting goats. Although it sounds strange, you can actually rent goats that will clear out large infestations in no time. 

Control: Manual removal can curtail small infestations; stifle with mulch.