We bought an older house (1960s vintage) that has St Augustine grass in the front and backyards. I have no idea what type of St Augustine, btw. This is our first year with this type of grass -- our previous house had Jamur Zoysia so we had a completely different experience.

In our current home, we have a heavy oak canopy throughout the yard (with heavy shade). The grass in the front yard is thick and green, despite the heavy shade. However, the grass in the backyard is thin and grows unevenly -- and nowhere is it thick and lush like the front yard. We basically didn't do anything last year except fertilize in the spring, mow and water regularly (we have an irrigation system). But nothing helped - even the spots that get sun didn't improve.

I'm not sure what to do to try and improve it this year. We were thinking about putting down top dressing to see if we can get some nutrients into the grass. Anyone have any advice (other than replacing it - which is not an option)?