Spinach grows best in cool weather, spring and fall sowings are best.åÊ A late August sowing for harvest in October or November is ideal.åÊ If the soil is fertile and moist, it is a rapid growing crop ready in 45 days or so.åÊ Harvest plants as they begin to compete for space with their neighbors and that way you can have several pickings for a small family.åÊ In mid June to mid July you will find that Spinach is bitter and bolts into a seed crop which makes it unusable for the table.