Jonathan Green Fast Grow Grass Seed is a rapidly establishing grass seed mixture, designed to fill in troubled areas in lawns or grow an entirely new lawn quickly. Fast Grow seed mixture contains annual ryegrass which is the fastest germinating grass seed variety. Lawns grown from Fast Grow can be overseeded with any Black Beauty Grass Seed Mixture to establish a thick, beautiful lawn that will persist for years to come. This seed germinates in 7 � 10 days.