The Grass Doctor

Overseeding and Crabgrass...?

Hi everyone. I live in Westchester County NY. Last year I had a terrible crabgrass problem and completely burnt out my lawn and started from scratch. Problem was, I started too late (mid-Oct) and I go decent but not spectacular germination (some spots were 65-70% and others close to 100%). This spring I had to chose between overseeding or putting down pre-emergent. I chose to overseed in mid-April. After I had some germination (by late April), I put down pre-emergent (early May). Around the same time, I had a ton of chickweed growing (mainly in the area that was 65%-70% covered) and so I spayed to kill it. Fast forward to today. The chickweed was successfully killed, but the pre-emergent was applied too late and I now have crabgrass again (not enough to warrant burning out, but enough where its a problem. In some spots, I would guess its 1/3 crabgrass, 2/3 grass). Perhaps more troubling is that much of that new grass I planted last fall and this spring is not looking so hot . Much of it is brown and dead (I used Scotts premium grass seed, Perrennial Rye/Kentucky Bluegrass mix). Even in the areas that were 100% lush and full in the early spring, its not looking nearly as good now (those area seem to have thinned throughout the spring and summer... almost as if it was so dense that the grass couldn't compete with itself.) In the spot that was 65-70% covered, I'm not sure if what I am seeing is the dead chickweed in between my healthy grass? And in the area that was 100% covered and very thick and lush in the spring, I don't know if I seeded too much and the grass couldn't compete with itself? Its strange. Anyway you slice it, I need to overseed again this fall, hope that it fills in nicely because I do it at the right time, and then do my pre-emergent early early next year (at least I think this is the best route). Now my questions... What are your thoughts on the brown, relatively thin, grass (in both areas)? When should I overseed (Was thinking making it a project the weekend of 9/5? What should I do with the crabgrass (overseed around it)? I tried using a crabgrass killer, but it didn't do much. I tried pulling it, but there is too much. I spend maybe 10:00 a day pulling up clumps here and there. When the crabgrass dies this winter, will my grass overtake the bare spots in the spring? And last but not least, I also have cicada killer wasps who are tearing up the lawn with their Burroughs. Any suggestion here? Why would applying the pre-emergent hurt my grass next year? Won't all my seed germinate this fall if I do it correctly? Thanks for your help! Another add-on. I just fertilized (this past weekend), with a normal fertilizer. Can I really use a weed and feed in 2 weeks and then a starter fertilizer 2 weeks after that? Wouldn't that be overkill?

Public Comments

1. best time to overseed is early fall -- late september. Apply a weed and feed around Labor Day. Two weeks later, mow the grass short 1.5-2". Then aerate your soil. You can rent a core aerator for about $50-60, or borrow the tow-behind kind from a friend. Aerate the CRAP out of your lawn - 6 or 7 passes in different directions. Spread a starter fertilizer over the whole area, then overseed, so that the grass seeds drop into the holes in the ground. Ideally, you'd then spread a 1/2" topdressing of compost or mushroom soil. T The grass should be growing well by late October, then choke out the weeds next spring. DON'T apply a pre-emergent for 1+ year after overseeding - it also prevented some of your grass from germinating. If crab grass is a problem NEXT fall, apply a pre-emergent the following spring in early March.