Spinach favors the short, cool days of spring and fall and will go to seed quickly in hot weather. Most of the varieties now grown are derived from the round-seeded type. Spinach plants tend to have either male or female characteristics, making them dioecious. They are wind pollinated and the fine pollen grains can easily travel a mile or more. To insure seed saved is pure, you should only grow one variety at a time and pull out any odd plants that may appear in the patch.
Spinach germinates well in cool wet soil.
In fact, it will speed things up if you soak the seed overnight, before planting. Seedlings can also be started indoors. Succession planting every two weeks should keep you supplied throughout the spring. However, if the temperature climbs above 60 degrees during the first 5-6 weeks of growth, the plants may bolt prematurely. For more information on cultural requirements of growing spinach, check out Growing Spinach in the Home Garden , from Clemson Extension in South Carolina or the Gardener's Guide to Growing Spinach .