Common Arugula (see Astro and Astro Organic below) is a fast and easy annual cool-season crop for spring and fall growing. It works well in containers, and makes superb micro greens at any time of the year. The leaves are best when young and tender — all flavour and very little spice.
The other varieties are grouped as Wild Arugula seeds. These are perennials in the genus Diplotaxis, so they are botanically distinct from Common Arugula seeds. They are sometimes listed as Sylvetta. They have all the flavour of annual arugula, but they do not bolt to seed in summer heat.