What is Japanese spirea?
Gardeners imported Japanese spirea (Spiraea japonica) to the United States in 1870 for use in Victorian-era landscapes. The easy-to-grow shrubs with the compact habit and pink flowers remained a favorite. Now Japanese spirea is one of many Asian shrubs threatening the ecosystems of our native southern forests.
Why is it a problem?
Japanese spirea has small seeds that wash away and rapidly take over disturbed areas; they are especially a problem when they reach stream banks. Seeds may also arrive in fill dirt used in home construction.
Once established, Japanese spirea forms dense stands that outcompete the native forest flora. Seeds from Japanese spirea can last for years in the soil, making the spread difficult to control. Note that although Japanese spirea is not yet on North Carolina’s statewide list of invasive plant species, it is specifically noted as an invasive plant in Buncombe County and the Great Smoky Mountains National Park.
How Can I Help?
Don’t plant Japanese spirea! Consider using native plants in your landscape. Some alternatives are:
• The native spireas, white meadowsweet (Spiraea alba),
• sweet pepperbush (Clethra alnifolia),
• silky dogwood (Cornus amomum),
• leatherleaf (Dirca palustris),
• Virginia sweetspire (Itea virginica),
• ninebark (Physocarpus opulifolius).
Consider removing existing plants.
If you can’t easily dig up your planting, cutting back and repeated mowing can help eliminate unwanted shrubs. Be sure to keep cutting back to prevent seed production!
For large infestations, herbicides containing triclopyr or glyphosate are effective. Be careful to follow label directions!
Article by Barbara Hayes, Extension Master GardenerSM Volunteer
For more information:
Weed of the Week:https://www.invasive.org/weedcd/pdfs/wow/japanese-spiraea.pdf
Distribution of Japanese spirea:https://www.invasiveplantatlas.org/subject.html?sub=3076
Invasive exotic plants in the Great Smoky Mountains National Park:https://www.nps.gov/grsm/learn/nature/non-natives.htm