Comparing leeks to onions is like suggesting that red is similar to orange, or that kale is akin to lettuce. Superficially, each pair shares some common ground. But ask a chef: Leeks and onion are not interchangeable.
As members of the allium tribe, leeks and onions do share family ties, along with chives, garlic, Egyptian onions, scallions, shallots and a host of ornamental flowering bulbs, including the spectacular giant purple allium.But in the kitchen, the two are very different. Leeks are sweeter and milder than most onions; chefs might characterize their flavor as "more complex."
Leeks have earned a reputation - rather unfairly - for being hard to grow. They're really not, unless one equates "length of time to maturity" with difficulty.
That part, at least, is true. A human baby can be conceived - and born! - in the time it takes a leek seed to become soup. Nine months is not unusual for long-season varieties. (Does that put a new spin on the price of leeks in the supermarket or what?)
The only other vegetable with a lifespan as long, other than asparagus, which is perennial, may be Brussels sprouts.
The incredible thing about leeks is that between the time the tiny transplants go into the ground and the long white roots are harvested, a gardener can practically ignore them. They like a little water during extended dry spells, and perhaps some soil mounded up around their swelling girth, but otherwise, hardly a peep out of them.
And because the tops are so pretty - gray-blue fountains of strap-like foliage - leeks can double as companions to bedding plants in the edible landscape. I've even seen a clever gardener use a double row of leeks as an interesting temporary hedge.
Not to say that all leeks take nine months. They don't. But don't fall for that "days to harvest" nonsense on the seed packets, either.
The scribes will tell you, for instance, that "King Richard" can be crowned in just 75 days. Clearly, the scribes have never grown them. Seventy-five days after "King Richard" seedlings go into my soil, the sproutlings are no more than middle-age princes.
Now, if the scribes mean that young leeks can be thinned in 75 days, quite true. The pencil-thin roots are sweet and tasty, rather like what scallions are to onions. Very good in summer soups and salads or roasted quickly on the grill.
To get a crop of leeks this coming autumn, sow seeds indoors in February. A standard soilless mix is fine, but good drainage is essential.
Seeds will sprout in a couple of weeks, like fine green hairs on the surface of the soil. Thin plants very gently or simply snip off the extras with a pair of scissors to avoid dislodging the roots of the remaining seedlings.
Leek plants grow very slowly. At transplanting time, about three months from the sowing date, the small green tufts will still look quite fragile. Though tolerant of cool temperatures, harden seedlings off anyway. They'll have to adjust to the higher light levels outdoors.
Prepare the bed for leeks as deep as any in the garden. The deeper the soil, the more of the root that can be buried. Only the part underground will bleach white, protected from the sun.
Add plenty of compost to feed the leeks steadily during their long incubation period.
When it's time to transplant, dig a deep trench for each row of leeks, piling the soil alongside. Lay the seedlings at an angle in the trench, about an inch apart, and gently push them upright as you fill the trench part way with soil. Just the top couple of inches of the leaves need to show. Try to keep the underground portions straight.
Gradually add more soil as the seedlings grow taller. When the trench is filled, in a couple of weeks, start mounding the dirt to cover the base of the stems.
Thin plants in summer to 2 or more inches apart. The roots can be close, making this long-season vegetable more space efficient. Harvest them whenever the spirit moves you, though light frost seems to improve the flavor.
I've tried three varieties: "Large American Flag," "Pancho" and "King Richard." There wasn't much difference among them.