Thank you for specifying where you live. The LA area and SoCal are not descriptive enough for lawn advice in the Southland. And as it happens I used to live between Aviation and the 405 on 121st street, so I'm fairly familiar with "late night and early morning low fog and clouds near the coast burning off around eleven with the sea breeze picking up by two and a high in the seventies." That monotonous daily weather report helps to define your lawn growing zone.

The problem with the Marathon II is that it is a dwarf and a fescue. Fescues don't repair themselves period, and dwarf fescues are much worse. Marathon II is the dwarfier version of Marathon. Marathon III is the dwarfier version of what you have. It was a good choice except for the wear and tear of your children.

You have the advantage of living in a spot where any grass can grow well. We call those transition zones. There is a big one from the central Atlantic coast inland to the Mississippi and slightly west. But living in that climate does not mean any grass WILL grow well under YOUR CIRCUMSTANCES. Your circumstances are kids and shade. If you did not have that much shade I was going to suggest Kentucky bluegrass. KBG is they type of grass that forms a fairly dense carpet of grass and refills the worn spots by itself. Since you have shade, that's out. Also out, among the sod forming grasses, is bermuda. Bermuda is the best grass for wear and tear but it really needs 8 hours of strong sun per day. The remaining alternative is St Augustine. St Aug is a coarse bladed grass, unlike all the previously mentioned grasses. But it should be the best possible alternative turf under the filtered shade.

I could suggest some varieties of St Augustine but you have to buy what you can find locally. What you don't want is the full sun variety called Floratam. But, having said that, you could put that in your full sun area and a more shade tolerant variety under the tree. The different varieties will blend together at the borderline what you put them and you'll never notice the transition. You should probably stay away from a dwarf variety. Here is a work in progress to describe the various varieties.

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If you decide to go with St Aug, you will be able to water once every other week. Some of the dwarf varieties are shown as fast growing. That means they grow fast to recover from damage. They don't grow tall, they grow horizontally fast. Again, you'll have to visit some nurseries to see what they sell. Then you can pick knowing what to expect from the available choices.

Thanks DChall, I really appreciate the thoughtful advice!

Originally I was concerned about how fine bladed the grass was; but now I think it's wiser to concentrate on having a healthy lawn - a fine bladed but half dead lawn doesn't look so good.

So St Augustine with Floratam in the sun, and Raleigh in the shade could work. Could this be over-seeded, or just kill and start over. Also, is this something that should be done after the heat of mid-summer (late August?) or wait until spring. I'm trying to be cautious about banning the kids from the lawn for another few months :-P.

Note - most of the shaded parts under the tree get a few hours of direct sun each day, 70% of the lawn is sun all day. I trimmed the south side of the tree pretty high to give the lawn more light :). This photo was taken later in the afternoon. Good observation!

Regards,
Walter

Here's an experiment that will cost you a little more than a dollar. Try putting one flat (piece) of St Aug someplace in the sun and see how it grows. That one piece will look like a weed patch, because the texture is so much different from the marathon, so you might put it toward the side. I think the St Aug will wipe out the fescue. Certainly, over the long run, the St Aug will dominate because anytime the fescue weakens for any reason, the St Aug will fill in. St Aug will be mowed at the mower's highest setting (or one notch lower). I don't know how much shade the Marathon can handle, but the tall St Aug should have an effect on it.