The outer leaves are coarse and dark green, while inner leaves are lighter green with a finer texture. Plant lettuce seeds early in the season, as soon as the soil can be worked. The seeds will germinate at soil temperatures as low as 40 degrees Fahrenheit. Space seeds in rows 12 to 18 inches apart and less than one-eighth inch deep. Keep the soil moist until seedlings emerge.
Spinach is another green that can be cooked or used in salads.
Crinkled varieties are often called 'savoyed. Like radishes and lettuce, spinach is grown mostly in the spring and will bolt, or flower, when the weather turns warmer. Some varieties like 'Tyee' will resist bolting longer and provide a longer harvest period. Sow spinach seeds one-half inch deep in rows 12 to 18 inches apart. Thin plants as they emerge to 2 to 6 inches apart.