Grace your dinner table with an easy-to-grow, elegant onion cousin: the leek. Sweet and mild, leeks are gentle on the digestive system and play the role of onion in dishes, only toned down. Unlike onions, leeks don’t produce bulbs, but stash their flavor in thick, juicy stems, looking similar to a giant scallion. Leafy stems are pretty and don’t need much room in the garden.
In the supermarket, leeks cost a premium; harvested from the garden, their a trouble-free bargain. Leeks are most famous for leek and potato soup, but they’re also good steamed like asparagus, oven-roasted, chopped in quiche, or wrapped in ham, baked, and covered with cheese sauce.
Frost-tolerant leeks thrive in cool weather. In Zones 7 and warmer, plants can overwinter in the ground, perfect for fall planting. In northerly zones, tuck plants into beds in early spring, as soon as soil can be worked.
Plant leeks in a sunny spot in soil that is fertile and well drained. Leeks thrive in traditional garden beds, raised beds, or even in tall containers. Space leeks depending on the stem size you want to harvest. For thickest stems, space seedlings 6 to 8 inches apart. For thinner, scallion-size leeks, follow tighter spacing, setting seedlings 3 to 4 inches apart. You’ll gain the best of both worlds by spacing seedlings 3 to 4 inches apart and thinning every other stem when they reach scallion size, allowing remaining stems to grow to thicker size.
Leeks need two things to thrive: high nitrogen and consistent soil moisture. If possible, add compost or organic fertilizer to the leek bed the season prior to planting. Otherwise, work in organic matter into the ground a few days before if possible.
To produce a succulent white stem, leeks must be blanched—that is covered or hidden from the sun. To do this, plant leeks into deep holes. Deeper planting yields a more drought-resistant plant. Make narrow trench 6 to 8 inches deep and tuck seedlings into the trench, pulling soil up to the base of the first green leaf. Water well.
After planting, mulch the bed with straw, grass clippings, or some other organic material to help soil retain moisture. Soak newly planted leeks with a liquid fertilizer such as Bonnie’s Herb and Vegetable Plant Food. Water leeks as needed until plants are established. After that, plants require an inch of water a week, either through rainfall or irrigation. Inconsistent moisture yields tough stems. Continue fertilizing plants with liquid fertilizer every week or so during the growing season.
As leeks grow, mound the soil from the trench around stems, beginning when stems are 1 inch thick.
Soil that tumbles into leaf folds can wind up trapped between skin layers in the stem. To keep this from happening you can slip a section of paper tube, such as from toilet tissue or paper towels, over the plants while they are still young as early as planting time. The tube will rot over the growing season, but will help prevent soil from getting into leaf bases during early growth.
On young plants, slugs can be devastating. Gather them at night, set traps, or use biological control. If there is a lot of rain in winter or early spring, leaf rot can set in. Rot shows as white spots on leaf tips that eventually shrivel. At this point there is not much you can do except pull the rotted plants and thin the planting to increase air circulation.
In summer, orange pustules on leaves indicate leek rust, which is worse in wet growing seasons. Remove affected foliage; later maturing foliage will be healthy.
Because they are so cold hardy, you could find that you still have leeks left in the garden that have made it though the winter, planted many months ago. At this point, dig them because they will throw up a bloom stalk that ruins the fleshy texture of the stem.
You can start pulling leeks from the ground just about anytime. Typically, you’d let them get least 1 inch or larger in diameter for the big white stems, but you can dig young ones to eat like scallions. If the soil is moist, they may just pull right out of the ground. If they resist, use a spading fork to loosen soil and then gently pull leeks by grabbing them at their base.
In zone 7 and warmer, you should be able to harvest leeks all winter long.
In colder areas extend the harvest season by mulching deeply around plants (up to 1 foot deep) before a hard freeze. You could continue harvesting leeks until they are locked frozen into the ground, but don’t let that happen. Dig them first and store.
Wash the stems thoroughly to remove soil and grit that may have collected between the leaves.
For short-term storage (up to one week), tuck stems into an airtight plastic bag and place in the refrigerator crisper. For longer storage in coldest zones, dig leeks with roots attached. Cut leaves back until just an inch of green remains on each leaf. Place stems in a box (root side down) packing with sawdust, clean sand, or vermiculite. Keep the packing moist and store in a cool place. Stems will keep up to 8 weeks.
To freeze leeks, wash, slice, and blanch for 1 minute in boiling water. Drain, drip dry, and toss into plastic bags. Add the frozen leeks to soups, stews, and other dishes.
Should I just plant the pot of leeks like I do with other Bonnie plants?
Will leeks grow in pots?
Just how cold hardy are leeks?
If I don’t blanch my leeks are they still edible?