A very old post that might be helpful when seeding
I wrote this to the forum two or three ago in effort to help those who planted seed that fall. By the time I wrote it was already after the fact, but I thought I would repost....beforehand this time LOL. So, read it in the present tense, rather than the past tense as it was written. Hope it helps.
I haven't been checking in very often the past week or two. I have been quite busy and miss you guys a lot. I've noticed several people are concerned with germination and hope to set your minds at ease somewhat if I can. I won't go too deeply into specifics because everything has already been covered over the summer months and besides, you've already sown your seeds.
Seeds need air, moisture, humidity, and then light. For all these reasons, I hope you trimmed back trees and shrubs prior to seeding. If you are overseeding, then mow the grass lower than usual, about 1-1.5 inches. Do this gradually over a 3-5 day period. They also need ideal temps, which is the reason late summer/early fall is the best time for seeding cool season grasses. Because temperature is something we cannot control, then it is fortunate the seeds will tolerate a variant range of degrees. You get the best germination when temps fall between 65 and 75Â°, but 80 or 85 degree weather will not harm them. It's just likely they won't germinate as quickly and you'll irrigate for an extended period. So, the worst you have to look forward to is the water bill. That extended period may also include adding a sprinkling each day. Instead of 15-20 minutes twice a day, make it 3 times a day since warmer temps will cause them to dry faster.
Those who used a slit seeder, I hope you didn't set the machine to plant too deeply into the soil. I often stated no deeper than 1/2 inch. A.J. has stated 1/8 - 1/4 inch, which is most ideal. But absolutely no deeper than 1/2 inch.
If kept too wet, you lose your seeds to rot because they can't get enough oxygen. Not enough moisture and your seeds dry out. Your effort is only to keep the upper 1 inch of soil moist. If you experienced a heavy rainfall, then don't irrigate again until the soil has absorbed it all not letting it dry out, then resume keeping it moist.
Here is irrigation schedule for the new seeds. Begin at whatever week you are after seeding.
water 15-20 minutes twice a day for two weeks
water 20-30 minutes once a day for one week
water 30-45 minutes once a day every other day for one week
water 30-45 minutes once a day twice a week for one week
move into deep irrigation, increasing the time to provide 1 inch of water all over and decreasing the frequency to just once a week. If you have to move the sprinklers at any point, the new location also receives 1 inch.
Starting off, the schedule supplies roughly 1/4 inch of water, then increases that amount while decreasing frequency of application at the same time. Like practically everything that concerns lawn care, this schedule is a general guideline and should be modified to accommodate your specific conditions. It's best to modify rather than put off your seeding plans. The reason is that while you may think it's still too hot in your area for seeding, change of weather can be sudden and winter/frost might roll in faster than you expect. That poses an enormous problem that you can do nothing about. The new grass needs time to form adequate root systems to survive winter or you lose it for sure. The lengths of time should also be modified if you have an automatic sprinkler system since that will not take as long to provide adequate moisture. So, decrease amount of water (time) but maintain frequency as is. The tuna cans test is recommended. Another reason not to put off seeding is that fluctuating temps can be damaging in the early stages.
If you did not topdress then shame on you. The compost or peat moss would have served as an excellent medium in helping to keep the seeds moist and also helping to absorb too much moisture. Even a light layer of straw would have helped. Personally, I would still advise that you do it since the rains are going to come if they haven't already. Trying as best you can to stay off the grass, just fling'em, as BP would say. Only now, you have twice the added concern of not smothering your seeds/seedlings in making sure to apply not more than 1/4 inch.
If you didn't core aerate where compacted soil is an issue, then shame on you again. Standing water creates the same problems as mentioned above and will prevent rooting. Try using the Nitron or another liquid aerating product. Nitron also says it helps with germination. You can still use it if you did aerate. I read somewhere that honey accelerates germination and there are lawn honey products on the market.
Remember also, your seeds have a natural germination inhibitor. They don't want to germinate so if you didn't freeze or prime (pre-germinate) them beforehand, do your best to create optimum conditions now by keeping up with watering and by fertilizing. We know phosporous helps the seeds germinate faster among having other purposes. Many people subscribe to the idea of fertilizing 2 or 3 weeks after seeding, and that's okay. My personal opinion is they need the "P" ingredient to help with germination and then all the other nutrients are readily available as the seedlings emerge.
One other point
It's okay if you seeded heavily, meaning a pound or so more than the recommended rate. However, "the more, the better" is not the standard and will inhibit germination while creating fungus.
That's all I can think for now. Differing opinions are welcome and please help with any points I forgot to mention or did not know.
All-in-all, I doubt you have anything to worry about. Last year, I feared the worst and thought the birds and squirrels really cleaned me out. I mean the squirrels were digging holes looking for more seeds. I hated them for good month LOL. I overseeded after mowing the lawn down to about 1.5 inches. The entire fall, I saw nothing - no seed - no seedling - no growth - nothing - nada - zip. But oh boy, when spring hit I was very, very pleasantly amazed.
Good luck, all!