Last year was not good for arugula. It was hot and dry from late spring, right through into fall. What remnant of arugula the rabbits didn't eat bolted almost immediately. I let the survivors go to flower, and there they stood until I tilled up their row to plant some spinach for this fall's harvest.
August this summer has been cool and wet. the spinach is coming up just fine, along with all the arugula seeded from last year. Looks like we're in for a bumper crop of both.