Growing Leeks in Arizona: Plant, Blanch, Harvest and Cook a Cool-Season Favorite
Leeks are one of the most underrated crops you can grow in an Arizona winter garden. They look like oversized green onions, they handle cold nights without complaint, and they hold in the ground for weeks once they are ready, so you can pull one whenever a recipe calls for it. A single short row can keep you in soup, braises and tarts from midwinter into spring.
The catch is that leeks are slow. They need a long, steady season, a little extra soil work to get those long white shanks, and patience. In this guide I walk through when to plant in the low desert and the high country, which varieties to look for, how to plant in a trench, how to blanch and hill, how to water and feed, which pests to watch for, and how to harvest, store and cook what you grow.
Why Leeks Are Worth the Wait
Leeks are part of the allium family, along with onions, garlic and chives. Unlike bulb onions, leeks do not respond to day length by forming a bulb. They just keep growing a thicker and thicker stem, which means you do not have to match a variety to your latitude the way you do with onions.
The part we eat is the shank, the tightly wrapped white and pale green section between the roots and the point where the leaves fan out. Everything you do in the garden, from deep planting to hilling, is about making that white section longer and more tender.
When to Plant Leeks in Arizona
Timing matters more than anything else. Leeks want to grow through cool weather, and they can take three to five months from transplant to harvest depending on the variety.
Low desert (Phoenix, Tucson, Yuma and areas below about 3,000 feet). This is a fall and winter crop. Start seeds in trays from about mid-August through October, or direct sow in September and October once the worst heat breaks. Set transplants out from October through early December. Plants grow steadily through our mild winter and are ready from late winter into spring. Try to finish your harvest before May heat arrives, because hot weather slows growth and can push some plants to send up a flower stalk.
Middle elevations (Prescott, Payson, Sierra Vista). You have two options. Plant in early fall and protect plants on the coldest nights, or start seeds indoors in late winter and transplant in spring for a summer and fall harvest.
High country (Flagstaff, Show Low, the White Mountains). Treat leeks as a long summer crop. Start seeds indoors 10 to 12 weeks before your last frost, usually in February or March, and transplant after the danger of hard frost passes. Harvest from late summer into fall.
Varieties to Look For
There are two broad groups of leeks. Summer or early leeks are faster and more slender. Winter or late leeks are slower, thicker and more cold-hardy. Here are some I would look for on seed racks and in catalogs:
King Richard is an early type with long, slender shanks. It is ready in around 75 days from transplant and is a nice choice if you got a late start.
American Flag (also sold as Broad London) is an old, dependable variety with thick stems. It is easy to find and does well in a desert winter.
Giant Musselburgh is a Scottish heirloom with short, very thick shanks and excellent cold tolerance.
Bandit and Tadorna are blue-leaved winter types that stand well in the ground and hold quality for a long time.
If you only grow one, American Flag is hard to beat for a first try.
Starting Leeks from Seed
Leek seedlings look like blades of grass for weeks, so do not panic if they seem slow. Sow seeds a quarter inch deep in a tray or small pots filled with seed starting mix. Keep the mix evenly moist and the tray somewhere bright. Seeds usually sprout in 7 to 14 days.
Once seedlings are a few inches tall, give them a haircut. Trim the tops back to about 3 or 4 inches with clean scissors. Transplant when seedlings are about the thickness of a pencil lead, roughly 6 to 8 inches tall. If you made your own soil blocks or newspaper pots (our guides: https://www.greenthumbhobbies.com/post/diy-soil-blockers and https://www.greenthumbhobbies.com/post/diy-newspaper-seed-pots), leeks are a great crop to start in them.
Soil and Planting in a Trench
Leeks want full sun in winter, at least six hours a day, and loose soil rich in organic matter. Our native desert soil tends to be alkaline and low in organic matter, so mix in a few inches of compost before planting. Loosen the bed at least 12 inches deep, since leeks grow a deep root system.
The easiest way to get long white shanks is to plant deep from the start. There are two common methods:
The trench method. Dig a trench about 6 inches deep, set seedlings in the bottom 4 to 6 inches apart, cover just the roots, and fill the trench in gradually as they grow.
The dibble method. Use a dowel or the handle of a tool to poke holes about 6 inches deep. Drop one seedling into each hole so only the top few inches of leaves stick out. Do not backfill. Just water gently, and the soil will settle in around the stem over time.
Space rows 12 to 18 inches apart if you plan to hill soil up later. In a raised bed you can tuck leeks into a block, about 6 inches apart each way, and blanch them with mulch instead of hilling.
Blanching and Hilling for Long White Shanks
Blanching means keeping light off the lower stem so it stays white, mild and tender. The trench or dibble planting does most of the work at the start. After that, every few weeks, pull soil, compost or mulch up around the stems as they grow. Stop just below the point where the leaves split apart. If you bury that point, soil can slip down between the leaves and leave grit inside.
In a raised bed, I like to use a thick layer of straw or shredded leaves instead of soil.
Watering and Feeding
Leeks have shallow, fine roots and do not like to dry out. In the low desert, plan on watering deeply about every 3 to 5 days in fall while it is still warm, then about once a week in the coolest part of winter, adjusting for rain and wind. The goal is soil that stays evenly moist a few inches down, not soggy and never bone dry. Drip lines or a soaker hose work well and keep water off the leaves. A layer of mulch cuts water use a lot.
Leeks are moderate to heavy feeders, especially for nitrogen. Side dress with compost or a balanced organic fertilizer about a month after transplanting, then again every four to six weeks. Stop feeding heavily as plants get close to harvest size.
Pests and Problems
Leeks are fairly tough, but a few issues are worth watching for:
Thrips are the most common pest here. These tiny insects rasp at the leaves and leave silvery streaks. Hose them off with a strong spray of water, keep plants well watered, and use insecticidal soap if a heavy infestation builds up.
Rust can show up as orange powdery spots on leaves, usually during cool, damp stretches. Give plants good spacing for airflow, water at the soil level, and pull badly infected leaves.
Bolting happens when plants are stressed by heat or an extended cold snap followed by warm weather. A flower stalk forms in the center and the stem turns woody, so pull those plants early.
Weeds are a real problem because leeks have narrow leaves that do not shade out competitors. Keep the bed weeded, especially early on, and mulch to keep weeds down.
Rotating your alliums is a good habit. Try not to plant leeks where onions, garlic or leeks grew last season. If you are growing garlic this fall (our guide: https://www.greenthumbhobbies.com/post/garlic-arizona), give the two crops separate beds when you can.
When and How to Harvest
You can start pulling leeks once the shanks reach about an inch thick, though many varieties will keep fattening up to two inches if you let them.
Do not just yank leeks out of the ground. The roots hold tight, and the stem can snap. Loosen the soil next to the plant with a garden fork, then lift the leek straight up.
One of the best things about leeks is that they store well right in the garden. In the low desert, mature leeks can sit in the bed for several weeks in winter. In the high country, they handle light freezes and can stay out under mulch well into fall.
Cleaning and Storing Leeks
Leeks are famous for hiding grit between their layers, even when you hill carefully. To clean them, trim the roots and dark tops, then slice the leek in half lengthwise, leaving the root end attached if you want it to hold together. Fan the layers under running water to rinse out any soil. If you are chopping them for soup, slice first and then swish the pieces in a bowl of cold water. The grit sinks and the leeks float.
Unwashed leeks keep in the refrigerator for one to two weeks. Wrap them loosely in a damp towel or put them in a bag to keep them from drying out. Sliced leeks freeze well for soups and sautés. Spread them on a tray to freeze, then move them to a bag so they do not clump.
A Few Easy Ways to Cook Leeks
Leeks have a milder, sweeter flavor than onions. When they cook down slowly in butter or olive oil, they turn soft and almost silky. Here are some of my favorite ways to use them:
Potato leek soup. Sauté sliced leeks in butter until soft, add diced potatoes and broth, simmer until tender and blend. Finish with a splash of cream and lots of black pepper.
Braised leeks. Halve leeks lengthwise, brown the cut sides in a skillet, then add a little broth, cover and cook until tender. Top with lemon zest, parmesan or a mustard vinaigrette.
Leek and cheese tart. Cook sliced leeks slowly until jammy, spread them in a pie crust or puff pastry, add an egg and cream custard with gruyere, and bake until set.
Leeks also pair beautifully with other cool-season crops. Try them with turnips (https://www.greenthumbhobbies.com/post/turnips-arizona), Swiss chard (https://www.greenthumbhobbies.com/post/swiss-chard-arizona) or a pot of potatoes for a whole winter meal from the garden.
Plant a Row This Fall
If you have never grown leeks, this is a great season to try. Get seeds or starts in the ground soon, plant them deep, keep the water steady and pull up some mulch every few weeks. By late winter you will have a row of tall, tidy stems that you can harvest one at a time for soup, tarts and anything else that needs a little onion sweetness. Let me know in the comments which variety you are trying this year.
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