Question
I have some large areas of crabgrass and/or goosegrass in my lawn (NJ); it is now dying, and turning color, whereas the grass is still green.  I have pulled some dead or dying clumps out, but that leaves big patches of bare soil.  I am going to overseed with a slit-seeding machine so I get nice early spring seedlings.  I assume since the weed portions are dying, I can overseed/slit-seed on top of the weeds?  I'm guessing the weed material will break down on its own over the fall/winter?

Answer
Important Point: Crabgrass is Warm Season Grass.  New Jersey Lawns are Cool Season Grass.  This is precisely why Weeds boom mid-Summer, just when Cool Season Grass is switching on the 'Sleep' Mode.  High Heat is as much a turnon for Crabgrass as it is a turnoff for Bluegrass, Rye and Fescue.  The weather you see right now, sir, is the OPPOSITE -- a trigger for Dormancy in Weeds, and a growth spurt for Lawns.  DON'T BE FOOLED into thinking the Weeds are DEAD.  Only SOME of them are dead: Annuals.  Any Perennial Weeds you have there are doing just fine.  GET RID OF THEM!

You are right on target to figure you have to plant something on the bare Soil.  Toss in some Grass Seeds.  A certain percentage will germinate early; some will survive, and in Spring you'll have a patch of Lawn ready to Mow.  Remember to include White and Red Clover in your Seed mix to boost Nitrogen au natural.  And don't forget to TEST your Soil to get precise readings on your Soil situation.  That's the surest route to happy Grass.

You can compost those nasty Weeds in the back.  After they cook, they'll be an excellent Soil Amendment.  Throw in some Thanksgiving Potato Skins and Vegetable Scraps, a few Halloween pumpkins, some old Cranberries, and you're in business.