Q: Dear C.J., This past Spring, I had taken down a couple of very large Oaks in my yard, which due to their proximity, were endangering my home. I ground the stumps, removed most of the wood chips left from the stump grinding, then placed a few inches of top soil over and planted seed..... several times!! But no grass growth. Any ideas on what I can do this Fall, to get this spot sprouting some grass?

S.Gallagher

Wading River, NY

A: Hi Steve,

You know, it’s really interesting that you should ask this. I was just at a labor day party yesterday and this exact same problem came up. Dame Judi Dench was throwing her annual shindig when she approached me for lawn advice while I was enjoying a diet cola with Mario Lopez. “Sure Jood” (that’s my nickname for her) I replied.

As we walked across the lawn, I noticed a section that had several brown areas that look exactly like your photograph. She stopped and pointed at one and asked if the problem could be “Allelopathy.” I was a little taken aback, as I didn’t know that she was so knowledgeable about turfgrass science, but hey, life is full of surprises, right? So I decided to quiz her by asking her to explain her understanding of allelopathy. She rolled her eyes at this, but I’m not totally sure if it was in response to my question or to the fact that Mario just took off his shirt for no apparent reason. Then she spoke.

“Allelopathy is when one plant releases allelochemicals that naturally inhibit the growth of other plants. The allelochemicals act as a natural herbicide to keep plants like grass from growing and competing for resources.”

I was impressed but she kept tapping her foot in that demanding way she has while she waited for an answer. “Well” I replied, “what sort of plants are you referring to?”

“These spots were all oak trees that were cut down to avoid them falling over the fence into Sean Connery’s yard. He gets SO annoyed with that. Anyway, I knew that oak trees could be allelopathic, so I thought that maybe the stumps were still giving off some of the biochemicals.”

Mario started jumping up and down excitedly. “Ooh, ooh, that’s sort of like when Kathy Griffin shows up to a party with her camera crew, right? And everybody runs for the nearest exit, right!?”

Jood patted him on the head and responded, “yes Mario. It’s very much like that. The plant in question makes it impossible for other plants to stick around.” Mario smiled.

Finally I responded, “well, how much topsoil did you lay on top of the ground down stumps?”

“About 2 inches.” she responded. Mario giggled for some reason.

Well, regardless of the possible allelopathy, you’ll definitely need more soil than that. I would recommend further grinding down of the stumps until you eliminate as much as is possible, a few feet if necessary. Then you can backfill with topsoil and it should be fine. This way, you’ll have a good deep root zone, AND you’ll avoid any possible residual allelopathy. Tree stumps can play havoc with grass when there isn’t enough room for the roots to grow. Even 4 inches isn’t enough.

She nodded and smiled. Then Helen Mirren walked by and they exchanged dirty looks. I have GOT to find out what that is all about.