Planting Grass

Two Sundays ago, Jenn's Dad came over and we planted some grass. We raked and prepared the ground, then spread fertilizer, then spread seed. So far, no grass. But today, somewhat at work suggested that it's still a little too cold for the grass seeds to grow. He said to wait until a few weeks of solid evenings in the 50 degree range. I'm guessing that's mid-May.