Japanese Spurge: I have a large circular area (20 -25') of Japanese Spurge...

Asked May 16, 2014, 8:19 PM EDT

Japanese Spurge: I have a large circular area (20 -25') of Japanese Spurge around a large maple tree that started to get patchy, dying out, yellowish last year and now again this spring. I vacuumed and raked out a lot of matted leaves from the maple tree last fall but none this year yet. The Spurge has been growing well and healthy for 7 years since we moved in, but is now thinner and less vigorous looking. What can I do to help it? Does it have a life expectancy that's running out? I don't know how old it is beyond the 7 years we've owned it. I can send a photo if you like.

Hennepin County Minnesota trees and shrubs japanese spurge horticulture

5 Responses

Thank you for the question. Japanese Spurge patches can live for years. I'm not sure how many, but I have personally seen patches thrive for 20 years. These plants grow best in moist shade in soil that has plenty of organic matter. They also prefer soil with pH of 5.5-6.5 with the lower end of the scale being preferred. You might consider getting a soil test to check this and here is a link on how to do this http://soiltest.cfans.umn.edu/ It's possible that there were too many matted leaves on your plants for too long. If this is the case, removing them like you are doing should eventually help. If they got too much sun or not enough snow cover, your plants may have scorched, or they may have developed disease from overcrowding and too much moisture from the maple leaves. Please check this publication to read about a very common disease called volutella blight http://www.ct.gov/caes/lib/caes/documents/publications/fact_sheets/plant_pathology_and_ecology/volutella_blight_of_pachysandra_04-10-08r.pdf If you have questions after doing your research, please resubmit your question with several photos. Close up pictures and one farther away that shows bigger areas of the bed might be helpful.

Some photos. 2 relevant.
Hard to post and know they are successful.

Thank you for the photos. I'm sorry about the delay in responding. To me, the photo showing almost the entire bed shows a pretty good stand of pachysandra. From what I can see from the photo, it looks like the problem area is on the edge of the patch. In my previous answer, I listed common problems which I still think are possible issues. Another option might be herbicide damage. Is it possible that an herbicide or other chemical product was applied to the turf grass outside of the pavement stones? If so, a chemical may have drifted onto the pachysandra on the edge and killed or injured it. Another thing to keep in mind is that when plants are growing under a big shade tree, the tree will always "win" in the competition for moisture and nutrients. Your tree has grown in the 7 years you have lived there and is needing correspondingly more water and nutrients. Maybe you need to water the pachysandra more often to compensate.
As you can see, there are many possible problems and I can't tell you which one it is. Look for disease following the link in my earlier answer and pay attention to cultural conditions like water and preventing leaves from matting and suffocating the plants. Good luck.

Thanks so much for this additional prompt answer. Can you help w/ what action if any I should take now. Should i just encourage w/ watering the sparse areas to fill in w/ spreading spurge? Should I pull the little maple seedlings sprouting up in these sparse areas? Will it all come back OK w/ enough time? I'm fine w/ waiting if it'll recover eventually. What do you think?

I would add supplemental water weekly, perhaps with a soaker hose under the tree, otherwise the large canopy of the tree will interfere with a traditional lawn sprinkler with the back and forth arm. Soak weekly and deeply. I would pull up the seedlings now while it's easy because bare soil is a weed magnet They don't stand much chance of growing to maturity in the dry shade competing with the pachysandra but they take up moisture and nutrients too. You could try transplanting some plants from denser areas to the bare areas to fill it in quicker. You can check soil pH and your plants for disease as pointed out in my first response. The eventual outcome is unknown but these suggestions should help.