This site has some great information specific to Wisconsin. Mary Fran had a question about spinach. Maybe she can discover a little help on this page. In addition, it can serve as a remind that spinach can be planted again about mid August for a fall crop. It is a cool weather loving creature!
From The Wisconsin Master Gardener Program
Planting
Plant spinach from seed when conditions are suitable. Spinach seed does not remain viable for very long, so purchase seed packaged for the current year.

You may be able to keep spinach seed under optimal storage conditions for a couple of years, but germination rates will probably be much lower.
Spinach is a cool-season crop that should be planted in early spring, about 4 weeks before your area’s average date of last frost. Ideal spinach weather is 50 to 60°F. Spinach does best in well-drained soil rich in organic matter, and will tolerate partial shade. Plant seeds 1-4 inches apart and about ½ inch deep. If you use the closer spacing, thin when the leaves touch, when the plants are about 2" tall,

using the tender leaves for salad greens.
Make sequential plantings about 2 weeks apart to continue harvesting spinach through the summer. Choose bolt-resistant varieties for later plantings. But even slow bolting types will not remain vegetative for very long, so each planting’s productive time will be short. Leaf quality declines when the reproductive cycle begins with seed-stalk formation.

A fall crop often tastes better than the spring crop because the temperature cycle of warm to cool weather is more predictable. Plant the fall crop in mid-August for a late-September (or later) harvest. Extend the season by covering the plants during really cold nights or grow in a cold frame. I have been able to harvest spinach in late December many years after growing the plants in a temporary cold frame (created from a curved glass pane and board ends set on my raised bed) when the fall weather has not been extremely cold.
You can also try a "winter" crop, planted in late September, that will grow a little before going dormant for the winter. Alternatively, just cut off the leaves of the plants of your fall crop, leaving the roots and growing point intact. These plants may overwinter to grow a new crop of leaves in the spring. In colder areas or severe winters, covering the plants with mulch may enhance their survival. Some varieties, such as ‘Bloomsdale Longstanding’, are hardier than others, and are more likely to survive the winter.