I'm in a similar situation (8 degrees, twice). Surprisingly that grass seems to be awakening, blade by blade. I installed some Raleigh St Augustine last fall and, more surprisingly, it's still green(ish). The Floratam definitely took a big hit, though. We also have a live oak tree that almost never drops any leaves. This season it's dropped about 80% of the leaves, so I have to blow those off the grass or it will get delayed and diseased.

Fertilize as normal (late May) and water as normal (deep and infrequent). I'm leaving mine unmowed until it needs it. April will be an important month to evaluate this.

Thanks. That makes sense. On close inspection, every square foot or so, there is a live stem with green blades. So I'm assuming it'll all fill in, but it may take a few years to do it. It was 5F twice, and then under 10F for a few days, but insulated with a layer of snow. The issue with fertilization is that I'd rather not end up fertilizing the winter grass, that is already coming on strong, such that it competes with the struggling Saint Augustine.

Yes, I too have a live oak, and it dropped a lot of leaves. Needs to get raked.

I'm surprised at my lawn. It's definitely coming back and about 2-3 weeks earlier than normal years.

On one hand, well fertilized weeds die better and faster than struggling weeds when you hit them with herbicide.

For the winter grasses, you might spray atrazine now. Otherwise wait until April 15th to spray it. I used to have poa annua, but not anymore. One dose of this stuff and it all disappeared.

If you use that, do it on a wind-free day, walk into the wind (because there are no wind free days in April), walk backwards so you don't have to walk through the wet grass, don't saturate the soil, and reread the directions 3 times before you use it. It kills horse herb almost overnight, but other grasses and plants take up to 3 weeks to die.

Just reporting back here. My lawn lives. Filling in nicely with green. Almost as if the whole lawn just went 100% dormant, which it never really does in a normal winter around here. But it could also be that everything on top got killed, but the roots survived. I did a big raking job a few weeks ago, which is very important to give the StA sunlight. So the lesson is that my StA survived 5F temperatures.

I'm always reluctant to use herbicides, because I have various crops surrounding the lawn. I just hand pluck the crabgrass and clover.

I cannot say mine is thriving. It is coming back but incomplete. There are areas of roughly 2 square feet around the yard that have no greening yet.

I was talking today with a friend who is a research botanist, and whose specialty is (wild) grasses. She said that there is no question that in 5F temperatures, the survival of St. Augustine was ENTIRELY due to the snow cover. We had 6-inches of snow about 24 hours into the bitter cold. Had the lawn remained uncovered for several days, with those low temps, St. Augustine would be toast. Snow, of course, is an insulator, with R=1 per inch. So six inches of snow keeps things kinda warmer. That how an igloo works.