Leeks are remarkably easy to propagate from seed, which is a good thing: It’s difficult to find plants at garden centers, though they’re available as young transplants via catalog and online.
Everything you’ll read about leeks says you can sow them directly into the garden, but leeks generally have a long growing season, ranging from 70 to 120 days, so you’re wise to start them indoors—and early. “I start them in the greenhouse by mid-February or so,” says Ben Saunders, owner of Wabi-Sabi Farm, an organic CSA operation near Des Moines, Iowa. He plants two or three leek seeds to a cell in a high-quality organic potting soil called Cowsmo, from nearby Wisconsin. Then he does something that most of the books I’ve read don’t recommend: In April, he plants those two or three seedlings per cell—now 3-inch plants (the seedlings resemble wheat grass)—into the same hole.
Saunders says that in a perfect world he’d plant the seedlings singly in rows, 6 inches apart. But he has the same problem so many backyard gardeners have—space. “I really need to use space efficiently, and I get a bigger yield this way,” he explains. Makes me wish I’d talked to him before I planted my three rows of leeks like a platoon of soldiers, single file and at attention.
Leeks have an undeserved reputation for being difficult. They’re pretty tough, but they don’t thrive on benign neglect, either. They’re heavy feeders (no problem if you amend your soil with compost to a depth of about 12 inches and feed with compost tea or fish emulsion throughout the season) and need regular watering. Both those factors may affect taste, which is sweeter than other alliums, says William Woys Weaver, Ph.D. He is based in Devon, Pennsylvania, and is an expert on raising and cooking heirloom crops, as his classic Heirloom Vegetable Gardening makes clear. “The soil,” he says, “and how much water they’re getting may affect the amount of sulfur—the sharp chemical that makes you cry when you peel onions—the plant contains.”