7 Tips for Growing Leeks

If you are a fan of potato leek soup, or butternut squash leek soup, why not grow your own leeks! For many of my years as a zone 3 gardener I didn't realize this was even an option. I paid the steep price in the grocery store time and again so I could make these yummy soups for our family. It wasn't until I saw a photo of beautiful, big leeks another northren gardener had grown in her garden, that I looked into growing leeks myself. And what did I find out? Growing leeks from seed is surprisingly easy in Canada and other similar, cool climates!

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Leeks are part of the allium family. They taste similar to onions but with what many consider a more pleasant, mild flavour. The allium family benefits many plants as a companion plant by deterring certain pests. (See below for more on this!)

When Should I Plant Leeks?

Leek seeds should be started indoors 8 to 10 weeks before your last hard frost. Sprinkle leeks seeds and cover with 1/4 inch of soil in a container at least 3 inches deep. Keep moist until seeds germinate. You can expect your leek seeds to germinate between 7 to 14 days. A benefit of growing leeks indoors is that they don't take up a lot of space, they grow well close together for the first 3 months, and your leeks can stay in the same container they were seeded in until it is time to plant them outdoors.

Trimming Leek Seedlings

Your leek seedlings will grow tall and look almost similar to grass. Trim your leek seedlings to keep them around 4 inches tall to prevent the tops from falling over and breaking. Simply take a pair of scissors and trim along the tops. As the leek tops get stronger you can let them start to grow taller.

Planting Leek Seedlings

Plant your leek seedlings outdoors after your last hard frost. (A hard frost can be considered temperatures below -6⁰C or 20⁰F.) For me, in the Calgary Alberta area, this is late April or early May. Choose a full sun location with loose, fertile soil to plant your leeks in. (Find more about garden soil here.) Gently separate your leek seedlings when ready to plant; you will find that the roots separate quite easily. Plant leeks 4 to 6 inches apart in rows 10 inches apart.

Unlike onions, leeks should be planted deeply, keeping just 2 or 3 inches of the green part above the ground. This encourages more of the white, crisp growth that is commonly used in cooking, on the lower part of the leek. Some choose to dig a trench for leek seedlings and slowly fill it in as the leeks grow. Leeks can also be hilled as they grow, to encourage more white growth on the plant.

When to Harvest Leeks

You can begin harvesting leeks when they are around 1/2" in diameter. Leeks tolerate a light frost well in the fall. Harvest before temperatures are expected to dip below -6⁰C or 20⁰F.

It is important that you don't attempt to pull out your leek plants to harvest them. Instead, use a shovel or pitchfork to carefully loosen the soil underneath the leeks and lift them out.

How to Store Leeks

Wipe off excess dirt from your leeks with a dry cloth. Peel off any excessively dirty or damaged outside layers. Trim the green tops to 4 inches. Place them in a perforated bag (I like these Ziploc ones from Amazon) in your refrigerator or root cellar.

Leek Companion Plants

Leeks are a great companion plant to carrots, (they repel carrot rust fly), celery, onions and spinach. Avoid planting near peas and beans.

Check out my full, free printable companion planting guide.

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