Baby-leaf salad green crops such as lettuce (Lactuca sativa), kale (Brassica oleracea), arugula (Eruca sativa), and mustard greens (Brassica juncea) thrive in the cool, humid climate of the maritime Pacific Northwest, particularly in the extended spring and fall seasons. To identify cultivars best suited for extended-season production in northwest Washington, nine leafy green cultivars were grown at two locations in the spring and fall seasons for 2 years. A high level of variability in crop performance was observed between seasons, locations, years, planting dates, and cultivars, indicating low-yield stability in baby-leaf salad crops across diverse environments and conditions. Overall, cultivars had a higher marketable weight in the spring than in the fall. Marketable weight was higher in Spring 2013 than in Spring 2014, and was higher in Fall 2013 than in Fall 2012. Days to harvest (DTH) were shorter in the spring than in the fall both years, and in both seasons DTH varied by ≈1 week between the two trial locations. Fresh weed biomass was almost 5.5 times higher in spring than in fall both years. Overall, pak choi ‘Joi Choi’ and mustard ‘Komatsuna’ had the highest marketable weight, lowest DTH, and lowest weed biomass across the widest range of environments and conditions, while beet ‘Bull’s Blood’ had the lowest marketable weight, relatively long DTH and highest weed biomass. These results suggest that baby-leaf salad crop cultivar selection differs for spring and fall seasons, and production can be highly variable between years and locations. Further, results suggest that growers should plant a diversity of crop cultivars each season to protect from crop loss and to achieve overall yield stability.