Creeping Charlie, "Glechoma hederacea" aka ground ivy and some other names, grows best in shady, moist soils so where it is a problem the first place for control is to look at the soil you have and correct any problems that might encourage this plant to grow, drainage issues, soil pH, nutrient levels. This plant grows really well from seed so the oft used spray some plant poison around may well get rid of what you have now it will not prevent future growth from seeds in your soil now or that get there in the future. A good healthy turf, which can be grown even in semi shade if the soil is right, will go a long way toward limiting infestations of this "weed".

Not sure Kim actually read what you wrote?...

The lack of proper amount of sunlight is probably the reason the grass is sparse to begin with. If there is not enough light, the grass won't grow no matter what else is or isn't there. You may want to look at the bigger picture you've got before you try the impossible (growing grass in too much shade.) Maybe you can prune the trees to allow more light without making them look butchered. Maybe the dead spots could just be mulched. As you probably know, walnut trees are a limiting factor in regard to plants that will grow near them, but there are many shrubs and perennials that could be added to the mulched areas for more interest. A couple really big rocks or dry stream bed can make an otherwise bare mulched area look great.

The grasses are totally different here so I can't tell you how well the kind of grass you have might do combined with CC when there is sufficient light. Around here, it's common for lawns to be filled with CC in full sun. Unless you are tee'ing off, they only way you can tell is when it blooms in the spring and the lawns turn purple. It's sooo pretty!!! If I had invented lawns, they would be made of CC, not grass. It's softer than the grass that grows here.

Incidentally, you may enjoy reading The Lawn; A History of an American Obsession by Virginia Scott Jenkins. A good follow-up to that, although it can get a little dry, is Redesigning the American Lawn; A Search for Environmental Harmony by Bormann, Balmori, and Geballe.

I also have quite a bit of creeping charlie around and have found that I can spray it occasionally with 2,4-D to hold it in check and let the grass thicken up. Where you are planting under black walnuts, I don't know if the alellopathy from the walnuts may damage your grass growth. If not, I would just limb the trees up a little if needed to allow more light to get in from the sides and plant red creeping fescue. That seems to be a pretty shade tolerant grass. Also, the trees tend to intercept rainfall and the soil under the trees probably gets a lot drier than elsewhere. You may need to consider supplemental watering to help keep the grass from getting too dry under the trees.

I've also got an area outside the kitchen window that is under a very beautiful, very very large boxelder. Provides wonderful afternoon shade for the entire house and really helps keep the house cool on warm summer days. But, it also pulls so much water that I really don't have much grass left under the tree and near the house. The ground is always dry, so I try to soak it well with the sprinkler at least once a week. Red creeping fescue is the only grass that does survive under there, even the creeping charlie has pulled back. The only thing that does well is chickweed, so I've kind of learned to tolerate it since it provides a green groundcover.

Grass has no problem growing under and around my Black Walnuts, even where the shade is relatively dense. The type os grass may determine how well it grows, but the Perennial Rye that was seeded there grows in thick, green, and fast every year keeping the Creeping Charlie that does grow well in other areas from growing there.

Apologies but I've misidentified my trees. They're not all walnuts, it's a mix of walnut and oak. That was a silly misstatement that I was reminded of when I was cleaning up about a baZILLION acorns from my drive this weekend.

I spray some weed b gone this weekend. I'll probably do one more application since it seems to be taking quite slow right now. it's been a little wet and temps are down so I'm assuming that's slowing the "b gone" part of the herbicide name. Just for fun I'm including a pic of my yard to illustrate the shade problem.

Ok, I linked to it over in the gallery. I was thinking it could be done inline here but i guess not.

The red box is my yard and the purple is charlie. As you can see even if I did trim the trees, which I prefer not to do, I'd still basically get sun only directly overhead.

Here is a link that might be useful: