The Puget Sound area is a mild temperate zone, which means vegetables can be grown here year-round. Spinach is one of the cold-hardiest of the leafy greens; others include kale, Swiss chard, cilantro, arugula, collards, beets, endive, escarole, and radicchio, all of which are being bred for further cold hardiness by John Navazio at the Organic Seed Alliance. Good sources for cold-hardy spinach seeds like ‘Winter Bloomsdale’ and ‘Tyee’ are www.uprisingorganics.com and www.seedsofchange.com. Sow seeds in good, fertile soil with full sun. The rest is timing.
Timing for Fall Spinach: Navazio recommends that seeds be planted in late August-early September, two months outside of summer solstice and not before August 20, or else the plants will get too much sunlight and “you’ll end up with baby spinach that will bolt.” This spinach will be harvested in October-November.
Timing for Winter Spinach: Start sowing September 10 for several weeks, making multiple planting until October 5. The goal is to get plants that “will fit under a teacup, with leaves as big as silver dollars, before they go into dormancy in November.” Teacup-sized spinach is the most cold hardy, says Navazio. As long as there aren’t any protracted hard freezes below 15 degrees Fahrenheit, this spinach will be harvested in February-March.