I have just planted some grass seed to replace some grass lost after the dry summer. I have been watering it daily for 3-4 days. How long should I keep this up?
Below quoted information comes from this answer, Can my lawn be saved or is it time to dig it up and re-sod?
I'm quoting the below couple of pieces of information as I believe they're useful to know (assuming you're not already aware)
After its first mowing you can stop watering (unless you receive no rain). If there's no rain, you will want to water deeply as you would for any cool-season lawn ie
All of the above information holds true for any type of cool-season lawn (cool-season grass seed), I can think of.
The reason you want to water so frequently is to keep the soil and seeds moist during and immediately after germination. If the seeds dry out while germinating, they will die.
When we've planted lawn in the past, we water at least daily -- sometimes twice if it is really hot and sunny, or windy (which also dries up the soil). If it is cool and overcast you can water once daily. If it rains, you don't need to water. You don't need to water heavily, basically so that it stays moist and the soil and seeds don't dry out. (You can check the soil in the area -- if it is moist, you don't need to water.)
Once most of the seed has germinated (i.e. the grass is growing), you can gradually decrease the frequency and increase the amount. Watering deeply will encourage the plants to send roots down deeper into the soil which will allow them to better survive dry periods. You just need to give them a chance to develop these roots initially.