I think bulldog mis-posted and has opened another thread for his question. For the OP, DO NOT TILL. I like to shout that. It is most important for those wanting to plant bermuda. When you say you have ground ivy, what is that? Can you post a picture? Ground ivy is a very common name that covers a lot of plants. Some are indestructible and some are easily eradicated. If bermuda is your goal and you want to seed, you have plenty of time to get ready. Bermuda seed will not sprout until the evening low temps are in the high 70s. Usually that is late June to July. Also are you willing to water the lawn? Usually the biggest problem with St Augustine is when the owner is unwilling to water. St Aug should force out dandelions but not all broadleaf weeds. If you want to restore the St Aug, lets do that.

Agreed, but I was really referring to xeriscaping. Ann 02 and I live in the high mountain deserts. It is a very arid climate but with large amounts of snowfall during a long winter. Still Jul-Sep are blisteringly hot with almost no precip. Wild temperature swings of 40-50deg each day. 100F during the day and a cold 50F at night is normal. So there was, and still sort of might be, a heavy trend toward xeriscaping like you see in AZ and NV. Crushed stone, bark, etc... But in the end we do have enough access to water because of the snow pack that the conditions are good for growing KBG and fescue. Almost everyone I know who decided to go the xeriscape route has begrudgingly ended up going back to a nice KBG lawn in the end. They always find out that the only real advantage to xeriscaping is a lower water bill. Other than that it is actually more work than a nice lawn. Still, they usually wish that the lawn didn't require quite so much nurturing to keep it healthy during the hot months. The ironic thing here about xeriscaping to save water... most people are charged for a minimum water usage and unless we are in a drought, they don't pass that minimum. So xeriscaping increases the maintenance and they get no cost savings.

Zach, you are not the first person to write in here with a lawn that looks like garbage. I've been reading here for 10 years and have been a moderator on three other internet lawn forums since 2003. Logan Labs has emerged as the premier soil test lab in the country. It stands head and shoulders above the second best professional lab in Texas. The same test that LL charges $20 for would cost $100 at the Texas lab. These pro labs serve farms and orchards around the world. With their high volume they can cut their prices. Only one of the university tests (U Mass) even offers what the pro labs offer. The university tests give you pH and the soil macro nutrients. The pro labs give you that plus buffered pH, micro nutrients, CEC, the salt components and their ratios. There are a lot more people who write back to say, "I should have gone to Logan Labs the first time," than those who write in to say, "I'm really glad I went with my local county extension service." Seriously, tilling is a huge mistake. It will not do what you want and it will bring new seeds to the surface to sprout. It will take 3 full years to settle and in the end it will be very bumpy. If you want to freshen your soil, the best thing you can do is cover it in 2 inches of shredded tree (or chipped tree) mulch for a month or two. By covering it with mulch it holds the soil moisture more constant and allows the soil fungi to multiply inn population. The beneficial fungi are what make soil healthy. Bacteria is a secondary player along with protozoa and microarthropods. Earthworms are nice but even they could not survive without healthy fungi. Once you get the mulch down, the improvement happens in a huge hurry. Have you ever seen how fast a bag of bread can turn into a bag of green mold? That's how fast it can happen in the soil. However I would argue that you don't need to do that. You can get the same effect by spraying any clear shampoo on the soil at a rate of 3 ounces per 1,000 square feet. Do that twice separated by 3 weeks and your soil will improve surprisingly well. Kill the weeds by spot spraying with Weed-B-Gone. The way you remove all the old grass is with a tool called a verticutter, power rake, slit seeder, or any (rented) tool with vertically rotating blades. You can adjust it so it just touches the soil. It will take all the plants out. Rake or blow the old grass away before seeding. Seed directly onto that soil and roll the seed down with a rented roller.

I agree for Buffalo, but for anyone else reading this, it really depends on where you live and the temps. If you live in the UP of Michigan, then August. If you live in Virginia or Tennessee, then maybe early Sept is too soon. Without looking at the calendar, the best time of year is after the summer heat breaks. The only time you would need 1/2-inch of topsoil is when you NEED to raise your lawn by 1/2 inch for better drainage. Otherwise, leave the topsoil out and just seed into the soil you have. You can scratch the surface if you want to, but don't bury the seed. It should be on top or very near the top. Then walk on the new seed to press it down into the surface for good contact with the soil. The soil will keep it moist enough if you water several times per day for a short time. If you have problems with your current topsoil, that can be fixed. Topsoil can "go bad" from a lack of regular watering and a lack of organic food for the soil microbes. Mulch mowing the lawn and mulch mowing the fall leaf drop are two great ways to return organic matter to the soil. If it is still not what you would like, then spraying with 3 ounces per 1,000 square feet of any clear shampoo will help water penetrate deeper into the soil and soften it. Also an organic fertilizer at least once a year will help improve tired soil. If that does not clear up your soil, then a soil chemistry test is the last resort. For many it is the first resort, but I like to try the organics first.