Category: Leeks

12/21/2025

Growing Leeks

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Growing Leeks

Summer leeks growing in my raised beds.

Introduction

Leeks, like onions, shallots, garlic, and chives, belong to the Allium genus. The scientific name of leeks is Allium ampeloprasum variety porrum, or sometimes called Allium porrum. Leeks grow with a round stem and flat leaves, but generally do not form a bulb. They taste similar to an onion but are milder. Leeks are white at the bottom, where they are protected from the sun, then turn lighter green until the leaves are darker green to a blue-green color. Leeks have been used since ancient Egyptian times, likely originating in Mesopotamia. The Romans brought leeks to Britain and Western Europe, where they have been cultivated since the early Middle Ages.

What Type of Leek Should You Grow?

A "Bulgarian Giant" leek, almost 3 feet tall!

There are three main types of leeks (not varieties). They are summer, fall, and winter leeks. The differences between these leeks are their cold hardiness and days to maturity. In general, the summer leeks, which are the least cold-hardy, also have the shortest days to maturity, whereas winter leeks take the longest to mature and are the most cold-hardy. Fall leeks tend to be somewhere in the middle. That being said, leeks can be picked at any time, even as baby leeks, if you need to use them sooner. Some winter leeks can even be overwintered, particularly in warmer climates. I live in zone 4 and have successfully overwintered leeks. Some do not survive until spring, depending on how harsh the winter was, the snow load, how well I mulched them, and the variety of leeks, but I usually have good luck getting most of my winter leeks to survive until spring. I like to grow a summer leek (usually “Lincoln”) and a winter leek (usually “Bleu Solaise”). I do not usually bother growing a fall leek because my summer leeks usually last until fall, since I have a very short growing season. That being said, the type of leek, whether summer, fall, or winter, can be somewhat fluid. For example, a fall leek for me in zone 4 could be a winter leek for someone living in zone 6, where it would overwinter quite easily.

Once you have decided on whether you want to grow a summer, fall, or winter leek, you need to decide on a variety. Some leeks are short and fat, others are longer and thinner. Some have disease resistance; others have very little. There is a good selection of open-pollinated leek varieties as well as newer hybrid varieties. If you are trying to decide what variety of leek to grow, please see my blog post on “Leek Varieties” where I list the most common leek varieties, what type they are (summer, fall, or winter), days to maturity, hybrid versus open-pollinated, and more. When deciding on a new variety of vegetable to try, I also often consult a citizen science project called "Vegetable Varieties for Gardeners," coordinated by Cornell University, in which average home gardeners can rate and comment on different varieties. Some varieties do not have an entry, but many common varieties have information on how well they grew in different parts of the country and under specific conditions.

Leek and onion seedlings under grow lights.

How to Grow Leeks

Leeks, like onions, can take 100 to 150 days to mature, although many less cold-hardy summer leeks are ready sooner, in 80-100 days. Leeks can be easily grown from seeds, either by direct seeding or transplanting after seeding in pots; or you can often buy transplants as well. Leeks are easy to grow, but they are heavy feeders and require good-quality soil with a pH between 6.0-7.0 and high in nutrients and organic material. If your soil is poor, you can add compost or composted manure in the spring before planting or in the fall, the year before. If you are starting seeds in pots (see my blog posts on “The Basics of Seed Starting” and “Growing Great Onions” for more information). ), sow 8-12 weeks before the last frost. Thin if necessary and transplant outside after hardening off when they are roughly 8 inches tall and as thick as a pencil. I always have too many plants in my pots and end up transplanting them when they are much smaller than a pencil; they still grow fine. You can also trim them as they grow in pots, so they fit better under the grow lights and use the cut-off parts as you would chives. The roots can also be trimmed somewhat when transplanting them to make them easier to plant. To transplant, I use a dibble (see my previous blog post on "My Favorite Gardening Tools") to make holes about 6 inches deep and plant the leeks deep (only 2-3” need to remain above ground), roughly 6 inches apart. If you wish, plant them in rows 12 inches wide, but I plant them in my raised beds approximately 6 inches apart in all directions with no designated rows. You can also create a furrow, approximately 6 inches deep, if you do not have a dibble. If you do not plant them deep, you can instead hill your leeks with soil or compost a few times as they grow, which helps produce longer, white stalks. It is recommended to fertilize with a well-balanced fertilizer, such as 10-10-10, mid-summer.

I use a dibble tool to plant onions, leeks, and garlic.

Leeks have shallow roots, so it is best not to allow the top few inches of soil to get too dry. I prefer to use soaker hoses or drip tape to water, as this keeps the water off the leaves and reduces the chances of fungal diseases. Generally, an inch of rain per week is sufficient, depending on the temperature and your soil composition (sandy soil requires more watering and clay soil, less). Because leeks have shallow roots, you want to be careful when weeding with a hoe or cultivator so that you do not dig too deeply and damage the roots. Mulching, with grass clippings (no herbicides!) or straw between the leeks and between rows, will reduce the amount of weeding you need to do.

Pests and Disease

The only problems I have had growing leeks (and onions) are onion thrips (Thrips tabaci). These tiny insects are usually a problem in hot, dry summers, but they rarely kill a plant. If you find tiny silver-white spots on your leeks or onions, this is the damage caused by thrips feeding. Another pest problem, which I have not experienced, includes the onion maggot (Hylemya antiqua), which feeds on the roots and stems and can stunt the growth of the leek, causing wilting and yellowing. Various diseases can affect leeks, including botrytis leaf spot, downy mildew, pink root, purple blotch, smudge, and white rot. I have never experienced these diseases, but some leek varieties, particularly F1 hybrids, are resistant.

Harvest and Storage

You can harvest leeks as you need them. If you are growing summer leeks, you should harvest any remaining leeks before a hard frost. Leeks will not die back like onions and should remain green until harvest. If my summer leeks start bolting, I usually take that as a sign that I should harvest them all soon after. Winter leeks can be mulched and hilled with soil if you wish to overwinter them or use them during the winter. I generally use leaves and frost cover to mulch and overwinter my leeks. Leeks can be stored for several weeks in a refrigerator (they will continue to grow very slowly, but too much growth reduces quality), ideally in a plastic bag with a damp paper towel around the roots. I like to buy food-safe, 5-gallon brine bags to store my leeks in, as they are generally too long to fit in a standard grocery store bag, even with the tops trimmed. If you have a separate refrigerator that you can keep colder, at ~32°F with high humidity, then the leeks may store for 2-3 months.

Freshly harvested leeks.

Preserving Leeks

There are two methods for preserving leeks. The recommended method is to dehydrate, although they can also be frozen with some caveats. Canning is not recommended for two reasons. First, the high heat required for canning will make the leeks mushy. Second, because of the way leeks grow, they can have soil stuck between the layers. This increases the bacterial load, potentially including the bacterium that causes botulism, making them unsafe for canning. Although you can freeze leeks, it is not recommended as they can develop a strong, bitter flavor. I have frozen leeks and have not noticed any bitter taste, but I also use them in soups or sautés that may mask bitter flavors. They do get very mushy once thawed, which can be unappetizing. Therefore, if you have an excess of leeks, it is recommended that you dehydrate them. If you are new to dehydrating, please see my previous blog post. Briefly, leeks are very easy to dehydrate as they do not require blanching (some sources do recommend blanching before freezing or drying). To dehydrate leeks, I wash and remove any dead outer leaves. I cut off the root end and the dark green leaves, leaving the white and light green portion. I like to cut my leeks in half lengthwise to wash out any soil between the layers. I then slice the leek halves into roughly half-inch portions. Dehydrate at ~125° until dry, usually 8-24 hours.

Using Leeks

Usually, the white to light green portions of the leek are used. The darker green portion, although edible, can be bitter, fibrous, and tough. Some recipes, like the classic cock-a-leekie soup, may have you boil the darker green portions to make the broth. In addition to cock-a-leekie soup, leeks are also traditionally used in potato leek soup, egg dishes, such as omelets and frittatas, braised leeks, pasta dishes, and more. Leeks can also be used as a replacement for onions or shallots in most recipes, although they do tend to break down and cook faster, so they should be added later in most recipes.

Conclusions

For me, leeks are one of the easiest vegetables to grow. They take up little room in a garden and are one of my favorite vegetables to cook. I was always intimidated to start leeks, onions, and shallots from seed, but as long as your seed is new for that year, they are very easy to start. I also love that leeks can be overwintered, providing you with fresh vegetables in early spring.

References and Resources

Cox, Jeff. 1988. How to Grow Vegetables Organically. Rodale’s Organic Gardening Magazine, Rodale Press, Emmaus, Pennsylvania.
Danto, Robin. Using, Storing, and Preserving Leeks. Michigan State University Extension. Extension Bulletin HNI51. February 2013. https://www.canr.msu.edu/uploads/resources/pdfs/leeks_(hni51).pdf
Growing Leeks in Home Gardens. Marissa Schuh and Jill MacKenzie. University of Minnesota Extension. Reviewed in 2024. https://extension.umn.edu/vegetables/growing-leeks#:~:text=In%20northern%20climates%2C%20start%20seeds,leaves%2C%20gradually%20filling%20the%20furrow.
Leeks – Key Growing Information. Johnny’s Selected Seeds. https://www.johnnyseeds.com/growers-library/vegetables/leeks/leeks-key-growing-information.html
Mahr, Susan. Leeks. Wisconsin Horticulture Division of Extension. https://hort.extension.wisc.edu/articles/leeks/
Vegetable Varieties for Gardeners. Cornell Garden Based Learning, Cornell University College of Agriculture & Life Sciences, Horticulture Section. 2025. https://vegvariety.cce.cornell.edu/main/showVarieties.php?searchCriteria=leek&searchIn=1&crop_id=0&sortBy=overallrating&order=DESC

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Leek Varieties

Leek Varieties

Growing Leeks

Growing Leeks

Introduction

What Type of Leek Should You Grow?

How to Grow Leeks

Pests and Disease

Harvest and Storage

Preserving Leeks

Using Leeks

Conclusions

References and Resources

Author

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