it does for me in z5 ... and the key.. is recognizing it in spring.. lol ... and the only solution i had was to leave the mess there all winter.. until i recognized the 50 million seedlings in late spring ... what do you have to lose??? over the years.. mine have all defaulted to white ... those pesky genetics and all ..... with a very occasional purple grown in ... so if color is important.. you may have to get some seed for purple and winter sow them ... ken

Where in CO are you? Do you have any watering restrictions? If you have a lot of thatch and roots in the top inch, you may be watering too often or too shallowly when you water. Most people on this forum advocate watering once a week and supplying an inch at a time. In the intermountain west, the arid climate and winds may make that impossible and you may need to water twice a week. But I would not water more often than that. Dinner plate sized holes should fill in by themselves, or you could cut plugs (maybe an inch or two across) from healthy areas of the lawn and plant them in the middle to speed the process. If you want to seed, it will be difficult to seed now and keep the grass alive during the summer, especially if you have any watering restrictions. I'm not sure how much time you have between the summer heat stopping and snow starting, but here, there's not much time, so a dormant seeding approach often works best. When you dormant seed, you put the seed down after it's too late for it to germinate and it germinates in the spring with the moisture provided by nature (melting snow, etc). It will usually germinate much sooner with dormant seeding than if you try to time it yourself, and you don't need to water it using this approach. That gives it a chance to get established well enough before the summer heat hits.

The label will tell you to wait a week. If you can wait that long, then wait a week. But in reality, you can reseed right away because Roundup only works through plant foliage, which seeds don't have.

Agree with lawniac. If all you need is seed, then drop the seed, walk on the seed, and water lightly every day until you get 80% germination. No need to buy or rent anything. 80% takes a week for rye, two weeks for fescue, and three weeks for Kentucky bluegrass. Do this sooner rather than later. If the grass comes in soon you have time to evaluate whether you need more seed. Here's how Mother Nature seeds: grass grows up to the seed head stage, animals walk past the seed heads and knock the seed off, more animals walk by and push the seed into the soil, and grass grows. It grows even without being pushed into the ground, but it seems to grow better in the footprints of the animals. I would also add that in 50 years of lawn maintenance, I've never used a tiller or dethatcher. I used an aerator once and saw no benefit. The single biggest improvement for me came when I changed from frequent watering to infrequent watering. The second biggest improvement was from mowing high. Third biggest improvement came from changing from chemical fertilizers to organic. The organic improvement was immediate (well, 3 weeks). These three changes have ended all the hassle I had with lawn care. I started mowing high in the 1990s but went to really high in 2012. Changed to organics in 2002 and deep watering in 2003.