Uh, yeah. I won't see daytime highs in the 80s until late October or November. I'll thank you in the future to not rub my face in it! ;-) What do you think you've learned about preventing crabgrass for next year? I'm curious to see what sinks in and what doesn't. Your lawn needs a lot of work. What do you want it to look like? Do you want it to be the yard of the month or is 'just green' good enough? If you want it to be the yard of the month, get a professional soil test from Logan Labs. If just green is fine, you can skip the soil test. There is a chemical post emergent for crabgrass. I'm an organic guy and don't know what it is. Look around for crabgrass and post emergent. Your lawn is in poor shape. You can start fertilizing now with organic fertilizer. Organics is the fast track to success in the summer. Try this with chemicals and you'll have a dead lawn in a week or two. The fertilizer of choice for this year is alfalfa pellets. Cost and performance wise, this is the one. Apply the first time at 10 pounds per 1,000 square feet. That is sort of an announcement to your soil that you are going to be applying more. If you overdose at first, the soil will not be ready for it and you'll get a little stink going on. You don't want that for a couple reasons. So start slow. Then after a month goes by, you can apply more at 20 pounds per 1,000. And after another month you can apply at 30 pounds or more depending on your wallet. 20 pounds is generally plenty but some people get really excited when they see the results and want MORE!!! Once you awaken the microbes in the soil, you cannot over apply. When you apply alfalfa pellets (rabbit food), you should moisten them immediately. The reason is so the birds cannot come in and carry them away. Moistening them makes them swell and burst open. It doesn't take much water. Over seed early in late summer or early fall. When the evening high temps start to fall, then it is time. If you don't have any Kentucky bluegrass in the lawn, that makes a good grass to fill in when you get weak spots in the fescue. KBG must have full sun, and it will go dormant in the winter cold. Other than that, it is a great turf grass. Here is a picture of the effect of alfalfa pellets. This is a zoysia lawn fertilized in May 2011 with a few handfuls of alfalfa. The photo was taken in June. Note the improved density, color, and growing height. This is what we're looking for in your lawn.

Last year, the crabgrass pretty much took over a 15x12 foot section of my front lawn. The crabgrass moved in after that section got churned up by a skunk looking for grubs - crabgrass tends to take hold in disturbed soil. I didn't want to use herbicides, especially since I applied nematodes to deal with the grubs. So I waited until the crabgrass was of a size to handle easily and then got on my hands and feet and yanked it all out by the roots. When I was done the entire section was pretty much all open soil, with very little grass surviving. I overseeded and the grass came in very nicely. However, I had no illusions that there were a million seeds in there, which is what prompted my post. This spring, then, I did use the pre-emergent and CGM. I wish they didn't feel that they have to add fertilizer to the preemergent but that's all I could find. I used CGM to further suppress germination but also to try to even out the areas that didn't get pre-emergent/fertilizer. I still ended up with some patches but that's sorted itself out by now. So far, I've not seen any crabgrass in the lawn and the area that I've reseeded looks absolutely wonderful. In fact, it's come in so thick that I've had a bit of a chore trying to mow it with my reel mower. Time to sharpen those blades! :)

Crab Grass is an annual "weedy" grass that germinates from seed when the soil temperatures and moisture levels are just right. A pre emergent, such as Corn Gluten Meal, can help prevent seeds from rooting and plants from growing, if applied right (enough at the right time). Those seeds can lay there waiting and can germinate anytime not just in early summer, so new plants can appear anytime during the growing season. A lawn, growing nice and thick, in a good and healthy condition is the best defense because a good thick turf will shade the soil and keep that soil temperature lower then what the Crab Grass needs to germinate. Not all options for killing Crab Grass are acceptable to organic growers since some are quite harmful to the environment, much more so then having Crab Grass in the lawn or garden. Mechanical removal is the least environmentally destructive and most efficient and if done before the plants set seed allow composting of the plants which is even more environmentally acceptable. While vinegar, by itself, will kill Crab Grass even that can be an environmentally unsound practice and there is no good reason to add other materials to the vinegar.

Application of pre-emergent is also dependent upon if you are planning overseeding in the fall or spring. Pre-emergent barrier will prevent all seeds from germinating. Grass seeds as well as weed seeds. So take that into consideration as well. As hawksster has mentioned, pre-emergent should be re-applied before the effectiveness of the previous application wears off. I use Prodiamine WSG 65 as my pre-emergent of choice. One application gives 6 to 8 months of protection. I apply in early May and then again towards the end of August/early September. This has worked out well for me.