Beet

Most gardeners know that beet seeds are hard to germinate evenly, but fewer know why: what looks like a single beet seed is actually a dried fruit containing 2 to 4 true seeds fused together. Every one of those seeds can sprout, and they will — often several of them from the same fruit cluster. This is why even careful beet sowings look overcrowded by the time the seedlings are an inch tall, and why thinning is not optional.

Sow 4 weeks before your last frost date, about half an inch deep and an inch apart. Once seedlings reach 2 inches tall, thin to 3-inch spacing — use scissors to snip at the soil line rather than pulling, which can disturb neighboring roots. The thinnings are edible; add them to salads whole. A second thinning to 3 to 4 inches may be needed as plants grow. Skipping this step is the most common reason home-grown beets end up spindly and malformed, pressing against each other and forking around the competition.

Beets want cool weather. They germinate best when soil is between 50 and 65°F, and they develop the most intense sweetness when they mature in cool fall temperatures. A spring sowing 4 weeks before your last frost captures the cool season before summer heat arrives. A second sowing in late summer for a fall crop often produces the best beets of the year — both the roots and the greens tend to be at their best after a few light frosts.

Boron deficiency is the failure mode most gardeners never identify correctly. It shows up as black, corky spots inside the root — the outside looks fine, but when you cut it open, you see dark internal cavities. Low boron is common in sandy, acidic, or heavily leached soils. A soil test is the correct diagnostic tool; adding a small amount of borax to the soil at planting is the fix, but only if confirmed by a test. Over-application causes its own toxicity problems.

Beet greens are ready to harvest at any size; the best flavor is when they're about 4 to 6 inches tall. Pull roots when they're 1.5 to 3 inches in diameter — most varieties. Left to grow past 3 inches, the flesh tends to become woody and the flavor develops an edge. The exception is Cylindra, which can go larger and stay tender. Store roots in the refrigerator with the greens twisted off and a half-inch of stem left intact, or pack in damp sand in a cool cellar. They can hold for weeks or months.