My favorite courses in college revolved around plants; their ecology, taxonomy, and affect on our environment. I get excited about things like FQI (floristic quality assessment). In a healthy ecosystem, native plants thrive. One major threat to native plants are invasive plants. These are plants that did not originate in our area but were brought in by gardeners. I spent a lot of time in college and working for the Department of Natural Resources getting rid of these pesky invaders. Unfortunately, these invasive plants can sometimes be purchased in local garden centers. The result: a distressed home owner who now has a plant taking over their property.
When bad plants happen to good people:
One such invasive plant is called Trumpet Vine, or Campsis radicans. This stunning vine entices a prospective buyer with it’s stunning flowers and promise of ease of care. Just look at this beauty:
The problem: this stunning plant will take over your garden; I’m convinced it could eat an entire house. You can kill the root three feet down into the ground and find it’s haunting leaves sprouting up through the middle of your concrete patio. I call the leaves haunting because once you have dealt with Trumpet Vine, it’s emerging leaves will be the source of nightmares.
Here is the same trumpet vine, eating even more fence: (note, these pictures were taken in the winter, during dormancy to better show it’s extensive structure)
Pay special attention to how the vine is literally busting the fence apart. The plant is known to reach over 40 feet in length, and the pace at which it can grow is astounding. Despite my experience with invasive plants, I actually purchased and planted one of these dangerous trumpet vines in my own yard. I knew they were invasive in Michigan, but I loved how they looked. When I moved to Colorado I was excited to see they weren’t listed as invasive here; the theory being that it’s a much drier climate and they are less likely to be a problem. I later discovered that they are listed as an “aggressive” species instead. Lesson learned: if a plant is listed as invasive in nearly every state in the US, don’t put it in your garden.
I am still finding this stupid vine growing in random places in my yard, even though I only had the trumpet vine growing for ONE season before I quickly discovered my mistake.
The trumpet vine above was inherited by my friend Marisa when she purchased her house. This vine has actually sprouted through the middle of concrete, and I do not envy the war that she is waging against this beautiful but evil vine.
Another plant that is considered invasive in many areas but not Colorado is Oregon Grape. We have one of these bushes in our backyard, and it definitely wins the “aggressive” award. The nice thing about the Oregon Grape is that in dry, high altitude Colorado I have not had issues with this shrub taking over our entire yard. I DO however have to HEAVILY prune it multiple time per year. The outer branches grow into the ground and become little runners for new plants, similar to what strawberries do. I would put this on the “plant with caution” list, and certainly never water it. No encouragement is needed for this highly aggressive plant. If you live somewhere with regular rainfall, it will be considered invasive- even though you can probably still find it at a garden center.
One of the most damaging invasive species is purple loosestrife. This beautiful flower, brought over from Europe in the 1800’s, takes over waterways and wreaks havoc on ecosystems. Purple loosestrife’s danger lies in it’s ability to produce an amazing number of seeds that have an unmatched germination rate. The plant and it’s rapidly generating offspring are capable of drying up marshes and ponds. Many states have actually made it illegal to sell or distribute this plant, yet you can sadly still find this plant in garden centers.
After doing some research on invasive species, particularly those in Colorado, I discovered one of the bushes in our yard is on the naughty list: privet. There are a number of varieties of privet, but the main hazard of this plant is the volume of berries that the bush creates. These berries are carried off by birds and dispersed. Because Privet is a resource hog, it likes to take over the plants around it. Like all other invasives, this ability to take over the native species are what put it on the “do not plant” list.
If you look closely at the base you can see how many new “trunks” the shrub has created. Even though this bush isn’t watered by our sprinklers, my husband and I have to do a major pruning on this bush multiple times per year. This picture was taken right after I pruned it to half of its size. Now that I’ve realized it’s an ecological threat I know I should yank it out, not excited about that prospect.
For reference, here’s what the privet looks like in bloom:
Here are the berries that follow:
I should note that there are a number of varieties of privet, ours has slightly narrower leaves. You can often find this shrub in garden centers and it is frequently used to create hedges in formal gardens.
Yellow Flag Iris
When we purchased our house we had a number of yellow irises in our yard. I was always amazed at their ability to multiply and dominate anything nearby, and sure enough: they are on the invasive species list. Key lesson here, if you have a plant that is being a bully, it’s probably invasive, or at the least aggressive (i.e. invasive in many other areas).
If you have this iris growing in your yard, rip it up and make sure to get every little piece of rhizome. We had a retaining wall torn out and redone and these irises were pulled out before the heavy machinery came in. I was SHOCKED to see some of these coming up again. I dug down into the ground and found the plants were coming up from tiny pieces of rhizome (root) left behind in the excavating process. Invasive plants are tricky like that.
How to get rid of invasive plants
The first step to getting rid of invasive species is knowing how to spot them. For starters, you can obviously guess which plants are the culprits by their ability to dominate your landscaping. However, if you are in the market for some new plants, check out invasive lists in your area. I have found that reputable garden centers (read: not DIY home centers) are usually very careful about what they keep in stock. I found this book called How to Eradicate Invasive Plants helpful. Full confession: I actually used Amazon’s book preview feature to read the pages containing a chart of the worst offenders, which is where I found my Privet and Yellow Flag irises listed.
Avoiding planting invasive species is the best way to keep them out of our ecosystems, but once they’re in place they are nearly impossible to eradicate. If you find yourself with an invasive flowering species, be sure to dig out the entire plant, root system and all. You can also cut off the heads of plants once they flower to help eliminate their spread.
Shrubs, trees and woody vines are an entirely different nightmare. When I worked for my college’s ecosystem preserve, we spent a lot of time eradicating a nasty shrub called buckthorn (left). My plant ecology professor had us cut these shrub/trees down to the base, then we applied a strong herbicide directly to the fresh cut. You HAVE to apply chemicals to the root system of invasive shrubs and trees, they can sprout up from even a tiny piece of existing root. Applying the herbicide or root killer to a fresh cut ensures that the chemicals travel down these roots and do their magic. If possible, get rid of invasive shrubs, trees and vines before they sprout berries or seeds, otherwise your battle will start over next season with their little evil spawn taking over your yard once again.
- Garden centers do unfortunately sell invasive plants, and even seed packets that contain invasive species. Be careful what you buy.
- Purchasing plants at reputable garden centers (ones that specialize in plants, not building materials) will give you a much higher chance of avoiding invasives.
- If you do find yourself at war with a plant, read up on special techniques to get rid of them. I do recommend the Eradicate Invasive Plants book listed above.
An invasive species is considered invasive because it originated from somewhere else and is now taking over the native plants. These native plants are important for our natural ecosystems to function properly. Help our environment out by keeping the local plants thriving! If you have a plant to warn others about, please post below!