Spinach is an easy, quick-growing crop, relatively free of problems as long as you keep to its favorite season: early spring. It should go in the first part of the rotation (leaves, fruits, roots, and soil-builders). My grandfather always planted his spinach in between the pea rows and I do the same. That way it enjoys the shade provided by the pea trellises. Since our spinach stays with the peas throughout the rotational sequence, it still doesn’t grow in the same place more than once every four years.
Spinach should be sown as early in spring as the soil can be worked, so we plant at the same time we put in the peas. Seed should be sown two seeds to the inch, 1/4 to 1/2 inch deep in rows six inches apart, or a foot out from the pea rows if you want to interplant as we do. Spinach sprouts and grows quickly in fertile soil; within a few weeks the first thinnings will be ready for harvest. Thin the plants to three to four inches apart as soon as they are large enough for the salad bowl. The remaining plants will fill in the row, and in another few weeks you can harvest them for the freezer.
Spinach can also be grown in the fall, but the timing is tricky up north, because if the seed is planted while the soil is still too warm it will not germinate well, and the plants may run to seed almost immediately. Planted too late, they will not mature before the onset of the cool, wet weather and the short days of late fall, which bring on mildew. Your best hope is to plant at the beginning of a cool, wet spell about a month before the first fall frost. If you’re lucky, though, you won’t get a weather pattern like that, because it plays hell with the harvest of everything else. Southern gardeners will have a much easier time, and can plant a fall crop as soon as the weather cools down for good.
As long as the soil is well drained, fertile, and not too acid (pH 6.5 or above), spinach has few problems, largely because it is in the ground for such a short time. The only problem we’ve had is leaf miners, and even this is rare. In an interplant with peas leaf miners are hard to control, but spinach grown in beds by itself can be covered with a floating row cover as soon as the seed is sown; this will keep out all kinds of flying insects.
We harvest spinach with a field knife, running the blade horizontally along the row just below the soil surface. This cuts the plants off just below the crown, so they stay in one piece for their trip to the kitchen. Scissors or clippers will work just as well. You’ll get about a bushel of spinach (twenty to thirty pounds) for every hundred feet of row.