Inspired gardeners often ask our crew with hopeful expressions: “I was driving down the street the other day and saw this amazing plant. Could you get me one of those?” As knowledgeable horticulturists, we must do some research before ordering the latest garden showstopper. We go through an in-depth list to learn about each plant. This list includes the plant’s sun/shade requirement, moisture tolerance, acidity/alkalinity preference, types of roots, and competition with neighboring plants. During this process, we sometimes learn that a requested plant is considered an invasive species in Massachusetts.
Invasive Plants
When it comes to plants, the term “invasive” can get a little muddied. For all practical purposes, an invasive species is a non-native plant that is introduced to a new environment where it behaves in a rather aggressive manner due to very little competition and/or extremely ideal growing conditions.
Although Poison Ivy or Golden Rod can be rather aggressive at times, they are actually not considered invasive plants since they’re native species. Two examples of common invasive species are Oriental Bittersweet and Japanese Knotweed. Both of these species are very aggressive. They’re often found growing on roadsides and quickly taking over areas.
Native Species In Massachusetts
Another term that’s commonly used in this discussion is “native,” which refers to a plant that is native to the local environment. This term also can be dissected, argued, and debated.
When we say a plant is native to our area, though, how far back are we going? When we go back about 12,000 years to the end of the last ice age, the glaciers that rolled down Route 128 almost certainly obliterated all “native” vegetation up to that point and transplanted them undiscerningly along its way. Let’s put a closer parameter on time: the Pilgrims landing at Plymouth Rock will be our time cap. We have pretty good documentation about the plants that inhabited our area at that time and those that were introduced for various purposes.
Is Euonymus Invasive?
We commonly get requests for this shrub in the fall. Admittedly, its month-long bright fiery red display is quite stunning. Outside of its fall showcase, however, I don’t personally find this shrub to be very aesthetically pleasing, and of course, because it’s invasive, I don’t recommend it!
Burning Bush (Euonymus alatus)
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Non-Invasive Burning Bush Alternative: Winterhur
Winterthur is a native plant, so that’s a great place to start. Not only is a native plant, by definition, not invasive, but it’s usually not overly aggressive either. But you know what’s even better about native plants? They’re being grown in their natural environment, which means that it’s very likely that the plant will thrive!
Viburnum nudum (Winterthur)
Here are some other great advantages of this non-invasive plant:
- Much nicer flower show in May/June (Burning Bush has a non-distinct flower)
- Flowers are followed by a colorful fruit structure that changes from red to blue throughout summer
- Fall colors feature maroon to dark red-purple
- Great food source for pollinators
- Better ornamental shaping from pruning (Burning bush tends to get sheared into “meatballs”)
Why is Japanese Barberry Bad?
Japanese Barberry is commonly requested – it be quite appealing to the eye! Visual appeal is typically what spurs a non-native plant’s introduction to an environment. Since Japanese Barberry is an invasive species, it can handle all sorts of difficult conditions including deep shade. It can thus outcompete native plant species, dominating edges of woodlands and choking out native undergrowth.
Japanese Barberry (Berberis thungerii)
Non-Invasive Barberry Substitute: Cotoneaster
There are a few great alternatives to Japanese Barberry, but my choice would have to be the Cotoneaster. If you want a taller form, Cotoneaster divaricatus looks very similar but grows to about 6’ – 8’. I think the Cotoneaster has a very interesting, unique structure. This shrub offers a skilled pruner (ahem) all sorts of possibilities to accommodate a client’s style preference; from formal and tidy to a natural and flowing look to even accommodating water features.
Cotoneaster horizontalis
Here are some other great advantages of this barberry substitute:
- Very hardy plant in all sorts of conditions
- Much broader, year-round interest
- No thorns! Barberry is thorny, a concern for little ones, 4 legged friends, and your local fine gardener tending your gardens
- Rabbit problems? Cotoneaster is seldom abused by rabbits
Invasive English Ivy
Though we often see English Ivy taking over landscapes and even houses, you can buy it almost anywhere plants are sold. This begs the question: is English Ivy is an invasive species? You betcha.
English Ivy is an aggressive exotic plant that outcompetes other plants. It can even kill off tall trees! English Ivy has been a standard go-to groundcover plant for years, especially in hard to grow, heavily shaded areas.
English Ivy (Hedera Helix)
It’s a rather hardy plant, but is not known for its flowering stage. In fact, English Ivy is most aggressive when it does go to flower. This is because it only goes to flower once it’s climbing vines have started growing.
Once English Ivy starts climbing a structure, it must be heavily maintained. This is especially important around the home, where English Ivy is capable of damaging gutters, wood fences, and cracked masonry. If it gets to the point of having to be removed, this ivy plant can cause damage at that point as well. It often leaves behind a residue that’s very difficult to remove.
Non-Invasive Ivy Alternative: Barren Strawberry
Barren Strawberry is a groundcover plant native to the Eastern United States. It can be a bit aggressive, but that can be a benefit when trying to fill an area quickly. Unlike English Ivy, though, Barren Strawberry is not a climber, so it won’t cause the kind of damage that many invasive species can cause when they spread. Personally, I notice this plant the most in the spring after the early spring show of bulbs and before the perennials and annuals really start rocking with the warmer weather of late May/early June. During this gap, I often see a solid blanket of yellow Barren Strawberry flowers in full bloom!
Barren Strawberry (Waldsteinia fragarioides)
One significant advantage of English Ivy when compared to Barren Strawberry is its shade tolerance. If you need a groundcover plant in a deep shade, I recommend considering Japanese Pachysandra.
Here are some other great advantages with this non-invasive alternative:
- Drought tolerant
- Not too many ground covers have a showy flower, but this one does!
- Excellent lawn alternative
This concludes our guide between some of the most commonly requested invasive plants and their more friendly, native alternatives! Many invasive species are not well suited (or perhaps too well suited) to our New England ecosystem. I hope you get to try out the alternatives mentioned in your own landscape – feel free to mention your own native plant alternative success stories in the comments!
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