Good pictures. Thanks. The weed in picture number three is called horse herb. If you are simply interested in green, that can be it's own ground cover. If you want a lawn; however, that HAS to go.

I'm curious where you are from that you think seeding is the thing to do to establish a lawn? In the south it is mostly done from sod.

If you are putting in some trees, that eliminates all the southern grasses except St Augustine. If you have more time than money, you can spend $5 on St Augustine sod and place those pieces around the yard. St Augustine will spread out about 10 feet per season and eventually cover the entire yard. $5 worth of St Aug sod should be at least 3 pieces.

Start by clearing some spots for the new sod. Carve it out about 3/4-inch deep to allow for the new soil on the sod. Place the sod and start to water it daily. Only water the sod and only enough to moisten the sod - no need to drench it soggy. Do it 3x per day (breakfast, lunch, and dinner time). Continue that watering for 2 weeks until the sod roots have knit into the underlying soil. Then start to back off on watering frequency. Avoid watering the rest of the yard to help keep the weeds down. Since you're in Austin I'm going to assume you will be okay with organic fertilizer. I would start with two heaping handfuls of alfalfa pellets (rabbit chow) per piece of sod. Buy it at your local feed store. Two handfulls is a lot, but it can take it all. Do that monthly to get it going. Moisten the pellets when you apply and come back the next day to sweep the green alfalfa worms into the sod. When the St Aug starts sending out runners, fertilize only over the runners. You are trying to favor the grass and cull out the weeds. Be sure the runners get some water when you are watering the sod pieces.

When watering mature grass the idea is to water deeply but infrequently. Deeply means a full inch all at one time. Infrequently means to let the soil surface dry out completely before watering again. This time of year (warming temps into the 70s) that might be every 3 weeks. As much as you can, keep the water off the rest of the yard. When temps warm into the 80s, move to watering every 2 weeks. With temps in the 90s, water every week. Always water the full inch when you water. When the grass is nearly at full coverage you will be watering with a sprinkler. Test your sprinkler by using tuna or cat food cans on the yard. Turn on the sprinkler and time how long it takes to fill up the cans. That is one inch of water.

Mulch mow the yard at your mower's lowest setting to kill out the weeds. HOWEVER, mulch mow the St Augustine at the highest setting. Eventually you will be mowing the entire lawn at the highest setting. When the drought comes, continue to mow the weeds but stop mowing the St Augustine. It can grow up to 32 inches high (I don't recommend it), but if yours gets to 6 or 9 inches it will be perfectly fine. Taller grass needs less water. Those short weeds might die with the heat, drought, and mowing stress.

I would not kill out the weeds, yet, until you are sure you have the St Augustine established. St Aug will choke out the grassy weeds. Horse herb is one nemesis that might not go away easily, but keeping the St Aug tall will really help. At least with these weeds you have something green. Well kept weeds can look like a lawn for a long time.

If the gravel is deep enough you could scoop it out, then do that.

I am so sorry for not responding to this sooner! I opted in to receiving notifications of any follow-ups, but wasn't actually notified.

Anyway, I've never established a new lawn before, so I just sort of assumed seed and sod were comparable methods, with seeding being the cheaper option. From what you're saying, it sounds like being strategic about sod could be a much better approach. I really appreciate all the detail, too!

Do you think using Bermuda grass sod would work just as well because of its growth habit? I love St. Augustine, but I'd like to go with something less thirsty in the long run if it can still manage to choke out the weeds.

How many trees and how much sun does your yard get?

Since we moved in February and some of the trees are still missing their leaves, it's hard to be exact about sun exposure. It seems to stay quite sunny, though. There are 3 big trees on the southeast periphery of the yard: a pretty narrow live oak and two hackberries.

Maybe a google map view or satellite view of your property would show some trees while they have leaves. Any kind of shading and you will need to rule bermuda out.