I am looking to put down some grass seed this winter. I bought a new house last fall, and since then I have cut down two blue spruces, which has large bare spots underneath, as well as the previous owner abused her lawn (scalped it every mowing, not enough water, bagged clippings, etc.) and there are several thin spots. I have made great strides so far by just letting it grow longer, not cutting it as short, and using a mulching mower. However, I still need to seed the bare spots where the spruces were, as well has thicken up a few areas that were abused the most. Getting to my question... I remember from my old house when the cable company had to come out and fix a buried line, when they seeded the trench the dug, the grass was different than the existing grass and the new grass was thinly bladed and bright green, compared to the thick blades, and dark green grass that was there before. So, after a while, I had a dark green lawn with a bright green stripe through my yard. I have also noticed people on my street who have recently aerated and seeded that the new seed is bright green, thinly bladed, and grows at a quicker pace than the existing grass. Their yards look funny because they have a lower layer of short, dark green grass, and then a taller layer of bright green. Looks to be about an inch worth of distance. Question: *Are these two separate types of grass, or the same grass but it just hasn't gotten established enough to darken up and thicken? *If they are separate grasses, will the established grass eventually take over the new grass, and the new grass is just there to allow the old grass to take it over? *If it is separate grass, and it won't be taken over by the existing grass, how do I know what grass to get at the store so I don't end up with two patches of different grass in my yard?