As that word is eternal so is everything that word begets. Peter then compares our existence on this earth to that of a flower. All flesh is like the grass and the flower. You plant a seed, a few days later there is a stem and then a flower. Several more days and it dries up and blows away.
Man is the same.
However, the seed of God produces plants of grace that are a sweet smelling savor to God for all eternity because they will wilt and die. When the Holy Spirit plants the seed of God in the ovum of a sinner's heart there is a new creation. Even your dog will know something happened.