Help with new grass

[mobo]

Hi, I am new to this so please excuse me if I don't make everything clear.
I planted my back yard with 100lbs of seed and raked it and rolled it but 2 days after we had hard rain for 2 days straight and I could see some of my dirt running off. I was wondering I need to replant my yard or not. I have been watering it every day and I see some grass coming up in spots but not the entire area I still have a lot of spots that I have nothing and I was told to give it more than 10 days to see what happens is this true that it will take more than that to see grass. I did not put any straw or anything down at the time. Oh I was also told I could spread seed on top and it will fill in all the areas but I don't see how it will grow. Please help

[mngrassguy]

If your soil moved, so did the seed. I would reseed those areas asap. I have great success broadcasting the seed right over the top of the soil. Be sure to use a good starter fertilizer now and again in 3-4 weeks. Good Luck

[mobo]

Thank you for your reply will I have to rake up the dirt and then reseed? Thanks again

[mngrassguy]

Only the areas that washed out.

[mobo]

Thank you again for your reply I will rake the area in the morning and put new seed down.