Spinach grows best when the weather is cool. Spinach bolts in response to warm weather and long days. Bolting means that the plant goes rapidly from producing leaves to producing a flower stalk and seeds. The leaves tend to develop a bitter taste.
Spinach is fast growing, matures its leafy foliage in about 7 weeks, and then quickly goes to seed. It will produce leaves for a longer period in cool, coastal areas. You can harvest by cutting just the outer leaves, leaving the inner leaves to grow larger, then cutting them at a later date, or cutting the plant about 1 inch above the soil line and allowing it to regrow for a second harvest. Crops are best sown in succession, at 2-3 week intervals from about October to April to prolong the harvest.
Plant spinach in sun to part shade, in rich, loose well-draining soil about 1/2 inch deep in rows about 1-2 feet apart. Keep thinning and eating the plants as they grow. Spinach should be kept evenly moist.
During the warm months, alternatives to spinach include New Zealand spinach and Malabar spinach. These plants tolerate warm weather and have a taste similar to true spinach. Plant seeds of New Zealand spinach in spring and harvest in the summer. To harvest, pinch the growing tips and stems. Malabar spinach is native to India and is a vine. Plant seeds in early summer and train onto a trellis. To harvest, pick and eat the leaves.