If you live where the summer heat has broken, you can seed any time. The best ways to prevent crabgrass are to 1. Never seed grass in the spring. If you have to seed grass in the spring, then expect to have crabgrass for one season only. 2. Come springtime, never treat your lawn like you were seeding it. This means leave your grass as long as you can stand it and only water once a week. Crabgrass seed needs daily watering to sprout; so does grass seed. Crabgrass seedling needs sunlight to grow once the seed sprouts; so do grass seedlings. If you plant grass in the fall, the crabgrass, being an annual, will not sprout. Planting grass in the fall gives it six months to mature the roots so your grass can survive the heat next summer. If you have tall grass, reasonably dense from lots of seed in the fall, then you should not have any problems with crabgrass next year. Just don't start daily watering next spring. Of course you have to deal with rain as it comes.

Yes, White vinegar works well, however if your looking to do an acre I would rec. using something else... plenty of diff types of vegetation killers out there. I use vinegar for around flower beds, and under treats as pot treatments.

One way to prevent over-spraying any kind of herbicide is to take an empty soda bottle with the bottom cut off and cap removed. Cover the weed with the bottle and spray it through the opening at the top. You can use plastic milk jugs if you have something larger to spray or the 20 oz. soda bottles for small weeds. For the nut sedge, I use dry molasses. TAMU has proven that molasses makes the roots stop growing. I used to have a good sized patch of nut sedge in my backyard and over the last few years have applied dry molasses and also use an organic fertilizer with molasses. Most of it has stopped growing out there. I have only seen two sprigs of it this year so far. Plus, it is much safer around pets and people.

Thank you Irving Ragweed for passing along your experience with 20% Horticultural vinegar. I had read that great care must be taken with using it as being a strong acid can cause damage to skin and eyes. I hadn't thought about the fumes. Yesterday I sprayed 9% vinegar from HEB. It seems to be a little more effective. The prostrate spurge and unwanted white wine cups were dried up within a hour of the treatment. But it had little effect on the Cedar Elm seedlings as you can see from this photo:~ ~ ~ Here you can see it killed the tops of the white wine cups, which are beautiful plants, but I didn't want a whole 'lawn' of them. Not sure whether the carrot like roots are killed so that they will not come back, they do seem much easier to pull up now so perhaps so. ~ ~ ~ I am pleased that this area is pretty well cleared up. The better mannered self seeded black foot daisies and four nerve daisies were left in place:~ ~ ~ But there are many square feet of gravel in the front yard and back where the vinegar resistant Cedar Elm seedlings are thick thick thick. I've laid a plastic bag over them just to see how long it will take to kill them. I'm not very hopeful it will be a solution ... ~ ~ ~ I've pulled them by the hundreds. There are millions/billions more. Bob said he will try pulling the hoe over and through the rocks to dislodge the seedlings, but I don't have my hopes up that it will be a viable solution and it would certainly be a lot of work. Suggestions?