When to Re-overseed after overseeding

Question: Hello,
I reseeded and replanted my lawn 8/25 (10 days ago). Some of the grass is coming in nicely while other areas aren’t coming in as well as you can see in the attached images. 
1)	Would you recommend I re-seed areas that aren’t coming in as well ASAP or would you wait a little longer? Because all the grass was planted on the same day, I’d assume since some new grass is already 1” tall, that if the seed was going to germinate it would have done so by now. I’m worried if I wait to long I’ll miss the window to get the seed down.
2)	Would you recommend I wait to re-seed if I can’t put seed down without walking on the new grass?
3)	When I re-seed, would you recommend I continue to water frequently to keep the newest grass seed moist, despite it probably being best to reduce the watering frequency for the recently germinated grass?
4)	I’m wondering why some areas germinated well and other’s did not. I’m thinking that a couple reasons some areas did not germinate well were
a.	They did not get as much water from the impact sprinkler.
b.	Maybe the seed to soil contact was not as good as it could have been. I only scarified the soil, threw seed down, and watered it frequently.
I saw on the UMD website that verticutting and aerating the soil before re-seeding can help get good seed to soil contact. My concern is that if the seed drops to the bottom of the hole or slit, won’t it be too far under to germinate? I thought covering your seed with more than 1/4” of soil was too deep; but with a aerator the seed could be dropped up to 2” below the soil.

Any guidance greatly appreciated!

Thanks!
Eddie

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied September 05, 2024, 5:00 PM EDT
response: Hi Eddie,  You could re-seed the areas that aren't coming in well. Maybe it just didn't take like you mentioned the seed to soil contact didn't quite line up. Aerating is good to relieve soil compaction. and while some seed may fall down into the holes it will still help with overall germination, especially if a soil test revealed that it is low in nutrients and you need to add organic matter.  You could water as needed to keep the new seed moist enough to germinate. It shouldn't effect the germinated seed too much to the point of a disease or fungal growth.  If you didn't aerate and the soil is compacted, you could use a garden fork and work it into the ground in the areas that didn't germinate before you overseed again. Then rake the seed evenly over the area.  Emily

responder: The Question Asker Replied September 05, 2024, 8:49 PM EDT
response: Good Evening Emily! Thanks for the suggestions. Does that mean I don't need to worry too much about stepping on the new grass when I overseed it with a rotary spreader? Thanks! Eddie

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied September 06, 2024, 12:04 PM EDT
response: Ideally you wouldn't walk on it but I think if you tread lightly and don't walk a lot it should be ok to overseed.

responder: The Question Asker Replied September 06, 2024, 2:47 PM EDT
response: I'll be light as a feather when I overseed it today. Thanks, Emily!

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied September 06, 2024, 3:06 PM EDT
response: you're welcome- have a great weekend.

responder: The Question Asker Replied September 06, 2024, 3:29 PM EDT
response: Sorry, actually one more qustion. When I go to overseed, is it best at this point to just throw the seed down and water it? I'm assuming if I tried to work the dirt (scarify/aeroate the ground, or rake in the seed I just put down to help the seed get past the dead grass into the dirt) it would be more detrimental to the new grass that just recently germinated. Or maybe only work the dirt in areas where almost no germination occurred (red circle in the picture) and essentially "start over", and just put seed down where more germination occurred, say 50% coverage or more?  Thanks! Eddie

responder: Answered by the Home and Garden Information Center (HGIC), University of Maryland Extension. For timely gardening information and tips, subscribe to our Maryland Grows blog and quarterly newsletter. Follow us on Facebook, Instagram, and YouTube. Replied September 06, 2024, 6:31 PM EDT
response: You could just work the soil in the red circled area and use a shovel or a garden fork to drive into the soil and slice through. Then just rake that area. That way you're not disturbing where the seed actually got started.

responder: The Question Asker Replied September 08, 2024, 10:19 PM EDT
response: That's what I did. We'll see how it goes!  Thanks again for the advice!