4-5 days. Astro Arugula grows quickly into a microgreen that is full of flavor and spice. Arugula is a fast-growing microgreen seed in general, and Astro Arugula is no different. Ideal for those needing a microgreen harvest in just a few days. The Astro variety of arugula displays slightly larger cotyledons than its related microgreen variety counter parts. Approx. 14,200 seeds / oz.