Best - great memory! That is yet to be seen, as those problem spots browned faster in the hot summer sun - so far so good though. Vicki - I did reseed with compost the year I started, which filled in a lot of the bare/crabgrass spots I inherited from the previous owner. The best weed prevention is more grass! Having said that, the key to CGM is 1) timing & 2) lay it on heavy. I'm sure someone can chime in with more precise temperatures, but I believe most (weed) seeds germinate when the soil temps hit around 65F. Since CGM (I use Blue Seal brand) seems to resist being washed away better than the more soluble synthetics I've tried, I put it down as soon as the air temp hits 60F. Last year, it was Feb! This year I put it down in April, right before that big rain storm we had (since you appear to be local). And by lay it on thick, I use 30-40 pounds per 1000 sq. feet. Due to the way organic fertilizers like CGM works, you can't over-fertilize (unless of course you totally bury your lawn with it!). I know it was the CGM (plus fairly thick, tall grass) that kept the dandelions out because I put very little on my lawn. I do CGM at 30-40 lbs / 1000 sq feet in the early spring when the air temp hits 60F and then I'll put soybean meal (also fairly high in protein) down in the fall sometime. Other than that, I mow high and water deep -that's it! Good luck and thanks for the kind words.

Epsom Salts a Magnesium Sulfate and Magnesium is an essential plant nutrient along with Calcium, Zinc, Phosphorus, Potash, Nitrogen, etc. But an excess of Magnesium in the soil will interfere with the plants ability to uptake calcium, so while it is a necessary element it is never a good idea to simply add some, Epsom Salts, without a good, reliable soil test to guide that application. Crab grass seeds in your area will not germinate for another 2 months so it might be too early for applications of pre emergent crab grass stuff. The single best way to keep cab grass from growing in your yard is grow a good, thick stand of tall grass that will shade the soil so the crab grass seeds will not find a good enironment to germinate in. If your mower will allow, cut you grass no shorter than 3-1/2 inches and 4 would be better, but cut as high as the mower will allow. This will encourage the grass to grow in thicker and crowd out the crab grass, or any other "weed" that might try to grow there.

Three herbicides come to mind, all liquids in their agricultural formulations. Treflan, Sonalan, and Prowl. To a lesser degree, Eptam might do the job also. Treflan is an ingredient in Preen. Not sure if the others are available for homeowners. I assume you would be applying them to a lawn. If so, read the labels carefully as Eptam has some activity on some perennial grasses. I would probably look to Treflan (Preen) first, then Sonalan, then the others. I think Preen is a granular, but you can apply it, then water it in with about 1/2" of rainfall or sprinkler irrigation within 24 hours and it will take the herbicide into the ground.

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.