NJ Lawns Community

Hey everyone, been lurking here for a while but now I'm stumped. I'm in Tenafly and finally got my KBG lawn looking decent after three years of love and labor. But this summer the crabgrass moved in and it's getting out of hand. I'm not looking to torch my bluegrass just to kill the crabgrass. Anyone have success with post-emergent products that are safe on established KBG? I've heard mixed things about quinclorac but curious about real experiences from guys dealing with this in northern NJ. My lawn is about 4 years old and pretty well established at this point. Sent from my iPhone while sweating over my lawn

Congrats on getting the KBG established brother - that's no small feat in our clay soil around here. The good news is you have options. Quinclorac is actually your best bet for post-emergent crabgrass control in KBG. It's the active ingredient in products like Drive XLR8 and that works great on established bluegrass. I use it professionally on client lawns in Cresskill and Englewood all the time. Just don't hit it during the heat of the day when temps are above 85, that's when you'll get leaf burn. Timing matters big time - hit those plants while they're still small and actively growing. Mid-August is actually not bad if you're seeing new germination. I'd hit it now, wait about 2 weeks, then hit any survivors again. One tip - water the lawn the day BEFORE you spray. Drought-stressed grass + herbicide = problems.

Adding onto what SoilScientist said but wanted to offer an organic path too since some folks don't want chemicals near their kids or pets. Corn gluten meal is hits or misses for crabgrass pre-emergent but for post-emergent you're really limited organically. That said, I've had decent results doing repeated mowings - when you cut crabgrass before it seeds, you break its life cycle. It won't kill existing plants but breaks the seed bank over a season or two. The vinegary acetic acid herbicides will burn it back but won't kill the crown. More of a temporary solution. What HAS worked for me organically in Teaneck: heavy compost topdressing in fall. Thick compost smothers crabgrass seedlings and feeds your KBG. I put down about 1/4 inch of screened compost fromackerson's in Saddle River every October. Year 3 I barely had any crabgrass.

+1 on the corn gluten and composting approach from WeedWarrior but adding the mowing angle real quick: You GOTTA mow your KBG higher than the crabgrass if you want to win this fight. KBG likes 3-3.5 inches, crabgrass likes being short. Raise your deck and let your bluegrass shade out the crabgrass seedlings. Also invest in a sharp blade - torn grass blades invite disease and can't compete. For what it's worth I run a Honda HRX217 at 3.25 inches on my KBG in Demarest and it tears through the thick stuff. Bagging vs mulching opinions aside for crabgrass - I bag and throw away to avoid seeding.

OK so I know everyone's pushing chemicals but wanted to share my experience going full organic in Alpine for 5 years now. My approach: aerify in fall, heavy compost topdress, overseed with more KBG (Midnight and Award varieties work great here), and maintain height at 3.5 inches. The idea is you crowd OUT the crabgrass by having your KBG so thick there's no light reaching the soil. It took me about 3 years to truly knock crabgrass under control but my lawn is SO much healthier now. The soil biology improved and my KBG is insanely dense. One thing that helped: I get my compost from Jersey Fresh in Paramus, they're actually decent. Cheap stuff from big box stores can have weed seeds in it so vet your sources.

Thanks everyone - this is super helpful. I think I'm going to do a combo approach: 1. Hit the existing crabgrass NOW with quinclorac (SoilScientist's timing advice makes sense) 2. Go heavier on compost this fall (Jersey Fresh in Paramus was mentioned, I'll check them out) 3. Adjust mower height going forward Quick follow-up: should I seed the bare spots where crabgrass dies or just let the KBG fill in naturally? I've got some pretty big dead patches and not sure if I should overseed now or wait until fall. First time dealing with this so appreciate the patience!

For those bare spots - DON'T seed now. Mid-August seeding in NJ is risky because you're heading into the worst heat of late summer plus crabgrass will still germinate. Wait until early September (after Labor Day) when soil temps cool down. That's prime time for KBG seeding in our area. Get yourself some Midnight or Baron and slit seed those areas. Right now just focus on killing what's there. You can lightly rake and amend the soil in those spots but hold off on seed until fall. Your KBG SHOULD spread into those areas on its own if it's healthy - KBG is a spreading grass. Good luck and keep us updated! Would love to see pics when you get it under control.