How high are you mowing? Set the mower blades as high as they will go, then the grass shades out the crabgrass. If it's a really bad infestation, it may take a couple of years, but you will see improvement the first year.

Totally non-toxic and safe.

Eliminating weeds by keeping your grass high is a fairy tale that the earth-crunchy crowd invented years ago. It does not work. I have an elevated deck and there is total darkness in places under it but weeds still grow in those areas. Keeping your grass high though does help it retain water.

There are 3 solutions to this problem:

1) You can pick crabgrass and other weeds out by hand. This is very tedious and sometimes difficult with weeds that have a long tap root or extensive root system. If you leave any of the root, then the weed is back again. Having said all of that, the method is chemical free and works fairly well but you have to be persistent with the method as new weeds crop up.

2) You have to use a herbicide that is selective for weeds. This can require multiple applications and possibly more than one herbicide depending on the extent of your weed problem. It also works best for weeds that are actively growing. It can be difficult to implement this method over a large area although you can buy some products that hook up to your hose and you can spray a rather large area. This method can cause damage to trees, shrubs, perennials, and annuals although it's not common if you use the product correctly. Some herbicides are pre-emergent which means that they prevent seeds from germinating. You will not be able to reseed or overseed with grass seed for several weeks in this case because they are also affected by this pre-emergent activity.

3) The nuclear option. You can spray the whole area with a non-selective herbicide like Round-Up, kill everything, and start over with seed or sod. Difficult to do for a large area of lawn.

This was a particularly bad year for crab grass. There must have been rain just when it was sprouting, because I've got it in parts of the lawn where I haven't seen it before.

I've read that if the lawn is more than 1/3 "good" grass, it can be rehabilitated over a few years, without starting over (going nuclear).

Although I agree that mowing high isn't quite as effective as it sounds, tall healthy grass will certainly be more successful against crab grass than unhealthy short grass. So maybe mowing high, having fertile soil and getting the right amount of water could do the trick, without chemicals.

There's almost no point in using a selective herbicide on it at this point, IMHO, because it's already setting seed (here, at least) and most herbicides will not kill the seed - maybe there's one that would, but I haven't heard of it.

If you really don't want to pull it (it can be very satisfying, if the lawn isn't too terribly big, and it's especially easy if the soil's damp) you still have a couple of options.

I'm going to pull a little of it, in some high-visibility areas, feed the lawn (lightly, with an organic fertilizer) and then plan to use a pre-emergent in the spring. These tend to be less toxic than other chemicals, and there's the non-toxic variety, corn gluten, which usually works for me - but which failed pretty miserably this year.

The nuclear option with sod sounds fabulous. I'm certainly not going to do it, but I do dream about it.

Two hard days of hand weeding and seeding....whoever suggested that 1/3 rule is nuts! Corn gluten in the spring and lots of prayers and do it all again for the next 2-3 years. Ugh. I have learned my lesson about ignoring my lawn.

Thanks for the motivation.

I am in the process of reseeding now. I did two applications of weed-killer to the crabgrass earlier. It got some of it but not all. Then I had an aggressive de-thatching and aerating done. I had a lot of dead areas from last year's drought and a bit of grub damage. I overseeded heavily on Friday and I am crossing my fingers, hoping for a rainy week. A thick lawn is the best defense against crabgrass. I've struggled as well as given up with that goal for years. Maybe this time....

I will try the preventative stuff next spring too. I also have a lot of ground ivy. Maybe that will help with that too. I think the ground ivy and the crabgrass accelerated when I stopped using Step 1/Halts a few years back.

bungalow, sorry if I contributed to your lost 2 days! I still haven't gotten around to methodically weeding my lawn yet - and to be honest I don't see it on my calendar in the immediate future - I'm just pulling a little whenever the spirit moves me. I should just go out there and get started, before the darn stuff smothers any more perennial grass, and before it sets seed.

Wendy, what will you use in spring? Does Halts really prevent annual weeds pretty effectively? I might consider it for the front yard, although I think I'll stick with CG out back, because we go barefoot a lot, and we have a dog.

Can't say that Halts was a miracle cure. Even when I was into the 4-step and used it, I still had some crabgrass. I just have a lot more now. And I never had ground ivy before but that could be a red herring. I am suspicious of some compost I applied to try to improve the lawn. Not sure if halts halted tbe ground ivy in the past. I have no idea when it started. I didn't notice it until it was way out of control.

Halts is similar to CG...timing is everything.