Is this an invasive plant? #855569

Asked November 20, 2023, 10:41 AM EST

Over the past few years, this ground plant has taken over my flower garden. in the early summer there are small (1") white flowers. Can you identify the plant? is it invasive?

Baltimore County Maryland

Expert Response

This looks like it is chameleon plant, Houttuynia cordata, also known as rainbow plant because of its ability to have multi-colored leaves. It is labeled as invasive in Maryland, as it is in many other states. This plant is an aggressive grower that is often used as a groundcover. It has the ability of growing up to two feet in total height. It is a native of Asia that was brought to the United States and introduced as an ornamental. It prefers moist soils and will survive in areas where the water table is high, and will survive in standing shallow water. It is shade tolerant. It spreads by way of rhizomes, which are very fragile and break apart easily, making removal very difficult. The leaves are in the shape of a heart, thus its Latin name Houttuynia cordata (heart-shaped). Control of this plant can be accomplished, but do not expect it to be done quickly. Any portion of the rhizome on the roots that remails will allow this plant to regrow. 

You will likely have to resort to using a systemic herbicide to kill the Houttuynia roots. Even though it can work well, repeat treatments will likely be necessary for established patches of this aggressive weed. Follow all label directions for the most low-risk, effective application of the chemical chosen. Some products may allow for (or even encourage) the addition of a surfactant upon mixing a solution for application. Surfactants, also called spreader-stickers or adjuvants, are additives that help a herbicide adhere to the leaves (in this case) or work more effectively. These products are sold alongside pesticides in garden centers since the two are often combined for certain uses, though not every product benefits from their use, so always verify this with the label usage details.

Early autumn may be the most efficient time of year to attempt herbicide treatments since the plant's deciduous leaves will be transporting more carbohydrates in the sap down into the roots for winter storage, and the absorbed chemical will then be able to "hitch a ride" more easily into the root system to cause dieback. Plants successfully treated might not show obvious signs of dieback for days or even a week or more after application.

If you wish to avoid herbicides, your only recourse will be to physically remove what you can by digging-out roots and to constantly keep trimmed-down all above-ground growth so the plant cannot photosynthesize. Every time it can regrow for a while the plant is recharging the root “batteries,” so to speak, for continued regrowth. That battery is depleted a bit every time the plant is forced to replace foliage, so if you can keep "discharging" that battery by making it keep regrowing without being able to photosynthesize, eventually it will starve and stop returning. This method might take years to achieve full eradication for well-established weeds, and will only work well if you have full access to the continuous patch. (For example, if part of the plant's spread continues into a neighbor's yard that isn't able to be controlled because you can't access it or they aren't willing to help combat it, that foliage could still fuel regrowth back onto your side unless you install some sort of barrier along the property line.)

Denying the foliage light instead by smothering the patch with a light-blocking tarp probably won't work as well in this case as it might for other weeds because this species could just keep creeping outside of the covered area to resume growing. Plus, any desirable plants growing among its leaves would be killed as well by the tarp. (Granted, desirable plants would also be damaged or killed by herbicide if directly exposed.)

Sorry for the grave news, good luck and feel free to ask further questions. 


Emily Porter Replied November 20, 2023, 11:57 AM EST

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