Spinach
This is not an easy crop in warm areas unless you have found the right planting date for your micro-climate. In Southern California, spinach is a fall and spring crop. Planting too early in the fall is disastrous if the soil is above 70 °F. The germination rate drops to 50%. If you have a soil thermometer, check the temperature at 2 - 4 inches depth before you plant in October. If it is above 70, shade the soil after preparing it for planting with a piece of 50% shade cloth laid over a frame 1 -2 feet above the soil. After a couple of days, check the temperature again. Water the bed to keep the soil moisture up: this will also help to cool it. As the temperature at night drops, your soil will gradually cool. Start planting seed in small blocks across the bed with a pre-spouted seed; soak seed overnight, then put between moist papers towels in a plastic bag. Refrigerate for a few days. Spinach likes light but only for 10 - 12 hours a day. Field testing at Cornell University showed that day length was the limiting factor in early spring planting because spinach bolts as days lengthen. They also found that wide ranges between day and night temperatures are factors in plant development -the plants thriving at 60 degrees day temperature and 40 - 45 degrees night temperature. This makes spinach a mid-winter crop or between 10 to 12 hour day length (In San Diego County, its mid-October to mid-February). Conclusion: Plant so crop can mature while days are short and cool. If weather cooperates, a direct seeding is in and out of the ground in eight weeks. Try Reemay row covers during Oct/Nov for a little shade and to keep birds from helping themselves. Spinach needs lots of nitrogen. In addition to pre-plant fertilization, use some liquid fish emulsion at the four-leaf stage. Sow seed ½ inch deep, 2 inches apart and thin to 6 inches. Harvest begins when plants are 6 inches tall. Pick the outer leaves and leave a 2 inch growing center.
Also check out ...
http://vric.ucdavis.edu/veg_info_crop/spinach.htm