Spinach likes to grow in a cool environment, with moist soil and a light dose of fertilizer.  In the cool months, plant out into a full sun location, during the warmer months, spinach does best when planted in a shady location.  During the heat of July, August and September, it may not be practical to grow spinach because it tends to taste bitter and will bolt quickly.  Spinach does not require heavy amounts of fertilizer, the plants can get by simply, by just adding one handful of compost and a quarter cup each of landscape mix and worm castings.  Harvesting the outer leaves as they mature, will lead to increased yields.