Patches which won't fill in, why?

I’ve been using Rachio for quite some time, and I’m very happy with it. Last year we put down new grass, as the foundation wasn’t good enough, so we added some topsoil and new sod (St.Augustine per HOA requirement). We’re located in south Houston, so quite hot. Since then I’ve also added a microdoser, which pulls liquid fertilizer from a tank, and mixes in ~0.2% of Miraclegrow, with great results. Grass and landscape looks very healthy.

However, there are a few patches which has appeared during last winter which doesn’t seem to fill in, no matter what I do, so I was hoping for some suggestions as to what can be causing it.

Rachio set to Flex Daily Schedule, with Friday being the only exclusion day, since we get the lawn mowed on Fridays.

Here are some pictures of the spots in question:

This is just in the front yard though, so maybe it’s dog urine from neighbors walking their dogs? (We do not have pets ourselves.)

Grateful for any input!


Just some thoughts:

Your lawn looks really good for only having been established last year! Ours is 5 year old Centepede in South Carolina, and we have larger bare patches (and much more bare) than you. In our case, I’m thinking construction material or contaminates have “poisoned” the area, and am considering digging down a foot, replacing all the soil, and re-sodding.

In your case, it looks like you’re going for perfection (not a bad goal!) since only the first spot would bother me. I’d simply buy a couple square feet of sod, scratch up the dirt, and position it, keeping it damp until it takes hold. If the replacement sod dies while still being properly watered, then look below the surface.

IMHO, you certainly don’t have a watering problem, and should be praised for your attention and work to obtain a high quality lawn.