Well, you guys have convinced me. I have some crabgrass that is hit and miss in small spots around the yard but I also have some pretty good sized concentrations. Even the smaller spots with just one or two plants, the plants themselves are mature, large and spread out so that it would be fairly easy to spray just that plant and not get too much else around it. Also, the RoundUp I had for another area where I didn't want anything else growing back for a while was the RoundUp Extended Control. Regular RoundUp says you can replant after 3 days. So, I think I'm going to try and hit the worst of the infestation with RoundUp, then I'll go over the whole yard with a light spray of Tenacity for the Yellow Nutsedge. When the crabgrass starts to knock back and die off, I'll rent a dethatcher and go over the yard with that, then rent an aerator, then a power seeder and reseed and fertilize. Oh, and unless we have an unseasonably cold fall or a really fast-coming winter, we can stay in at least the mid-40s at night and mid-60s to mid-70s all the way until Thanksgiving around here. It's really hit or miss and, my luck, we'll have a really cold fall, but I'm really not too worried about sowing grass in mid to late September. I've looked at some of the information from the local county extension agents and they say that as long as the seed is in the ground by the end of September in our area, the grass should have time to be well rooted before winter hits. Sometimes it will still be good when seeding as late as mid-October but, with the way the weather is around here anything past the end of September and I'd really be pushing my luck. Soooo, that gives me a month to kill the worst of the crabgrass, dethatch, aerate, power seed and fertilize. Oh, I need to find the time to close down and winterize my pool too. It looks like September is going to be a really busy month! I may have to cancel my vacation days before Thanksgiving and take a few Fridays off instead to extend a few weekends and get everything in. Thanks for the advice guys. - Byron

St Aug. Where are you in SoCal?

I didn't ever mow this until a few days before the picture. This is in a garden bed not the lawn. I used a string trimmer. My lawn is quite well-maintained but I've left this in the hosta bed for years. It grows in clumps. There was one in first year. After three years there are 5. Not invasive. I wanted to know what they were before I dig them up. Won't change my action just wondering. The other weed isn't nipplewort I don't think but I didn't give a decent picture. Now I know what nipplewort is and it does have yellow flowers but they're different and the leaves aren't the same. The weed I have is UGLY (this picture doesn't do it justice in it's unattractiveness) and gets brown pods after flowering.

While almost all of Trailrunner's advice is spot on, I'm going to take exception to the comments about lime :-) Liming a lawn - or not liming - has no impact on killing weeds or weedy grass. And a lawn or the soil bed in prep for planting a lawn does not automatically require lime. Most types of lawn grasses prefer a soil pH of neutral (7.0) to slightly acidic (6.3 to 6.5). Liming is only necessary if the pH is lower than 6.3. And you can over apply lime. Too much too frequently and the pH will become excessively alkaline and desired grasses will become starved for nutrients. Never apply any amendments willy nilly. Get a professional soil test done and then apply only the amount and frequency advised.