Q: I’ve had just enough success with carrots to make me want a repeat. In my first garden I grew great ones, but I’ve moved a few miles away, and now I can’t even get the seed to sprout very well. The only change I can see is that the soil is rockier. — Marcy Canady, Zanesville, Ohio
A: Your hunch about the soil is a good place to start. Carrot seeds are tiny and have trouble breaking through heavy soil. Carrots are one of the few vegetables that warrant sifting out stones before making a seed bed—a lot of work but something you need do only once. And you can sift just small patches at a time. A 4- by 4-foot patch can yield 200 to 300 carrots!
To sift out the stones, make a strong frame of 2 by 4 lumber and cover it with half-inch galvanized wire mesh (hardware cloth). The frame should be roughly as wide as your vegetable beds and 2 or 3 feet long. At one end of the bed, excavate a 2-foot-wide strip and reserve the soil in a wheelbarrow or set it aside nearby. Place the frame over the hole on bricks or concrete blocks so that it is raised above the soil level. Then start sifting, digging soil from the adjacent area and working it through the screen. Make your way methodically down the bed, removing soil to about a shovel’s depth, 8 to 10 inches. When you move the sifter over the last area, use the soil you reserved at the start. Any stones you accumulate can be used as gravel or fill.
Carrot seeds germinate best in cool weather. The ideal time to plant is about a month before tomato-planting time. Planting depth is crucial—too shallow, and the seed can dry out; too deep, and it can exhaust itself trying for the surface. A quarter-inch or slightly deeper is ideal; certainly no more than a half-inch. If the surface of the soil dries out, it can crust over and thwart the emergence of seedlings. But watering can actually make things worse by compacting the ground. I cover seeded beds with a layer of landscape fabric or spun bonded row covers to keep the surface moist longer and reduce compaction during rains or watering. Five days later I begin checking daily for sprouts. When about half the seeds have germinated, I remove the cover.
I also have found that it helps to plant the seed on the heavy side; a clump of seedlings can break through heavy soil better than a single individual. Thicker sowing calls for ruthless thinning later, however. Ultimately you want carrots spaced 2 to 3 inches apart both in rows and side by side, but in practice this is hard to achieve. Instead I plant across the bed in shallow furrows 3 to 4 inches apart. When I lay down the seed I try to get one seed about every 1/8 inch. This makes for a pretty thick row, so when the plants are about 1 inch tall I pull out clumps an inch apart. I thin again as soon as the foliage of the remaining clumps begins to touch. Earlier thinning is better than later. Since my rows are several inches apart, I thin for a final spacing of about 1 inch between mature carrots. Early thinnings go onto the compost pile, so that slugs and carrot flies won’t be drawn to the bed. I don’t start using the thinnings until they are big enough to clean easily, about finger size.