Spinach

Spinach is one of the few vegetables that can germinate in soil cold enough to make a tomato seedling rot in place. It's a plant of early spring and late fall — the narrow windows when the soil is above freezing but the days haven't gotten warm. Plant it six weeks before your last frost date and it will quietly germinate, take its time coming up, and give you leaves by the time the peas are blooming. Plant it in May and it will send up a flower stalk before you harvest anything worth eating.

The word for what spinach does in warm weather is bolting — the plant shifts from making leaves to making seeds, and once that decision is made, the leaves turn bitter and the game is over. A stretch of days above seventy-five degrees is usually enough to trigger it, and there's no reliable way to reverse the process once it starts. This is why spinach is a spring crop and a fall crop, never a summer crop, unless you live somewhere the summer stays cool.

Sow directly in the ground. Spinach transplants poorly — the taproot doesn't like being disturbed — and direct seeding in cold soil is one of the few times that method is actually easier than starting indoors. Scatter the seeds about an inch apart in rows, cover them with half an inch of soil, and wait. Germination can take two weeks in cold ground; that's normal. The seedlings will be small and slow at first, but they'll pick up speed as the soil warms.

Thin to four inches once the plants have a few true leaves. Crowded spinach doesn't grow well, and thinning early means you can eat the thinnings — baby spinach is just spinach you pulled too soon. Keep the soil consistently moist; spinach that dries out tends to bolt faster. A light side-dressing of compost or a nitrogen-rich fertilizer midway through the season can push the plants to make more leaves before they flower.

The fall crop is often more reliable than the spring crop because the plant is growing into cooler weather rather than racing against warming soil. Sow in late summer — about eight weeks before your first fall frost — and the plants will size up as the days shorten. Many gardeners find that fall spinach tastes sweeter than spring spinach; a light frost tends to concentrate the sugars in the leaves.

If you want fresh spinach through the winter in a mild climate, or through late fall in a cold one, row cover or a simple hoop house can extend the season by several weeks. The plants won't grow much once temperatures drop below forty, but they'll hold in the ground and you can harvest leaves as you need them until a hard freeze finally ends the crop.