How to Grow Leeks: From Seed to Harvest

Leeks are one of the most rewarding vegetables you can grow at home. They're hardy, forgiving, and shrug off cold that flattens more tender crops — many gardeners are still harvesting them in the depths of winter. With their mild, sweet onion flavour, leeks earn their place in soups, stews, and roasts long after the rest of the garden has packed up for the year. Best of all, they ask very little of you once they're in the ground.

This guide walks you through growing leeks from seed to harvest, wherever in the world you garden.

Why grow leeks?

Leeks (*Allium ampeloporrum*) are close cousins of onions and garlic, but they don't form a bulb. Instead you eat the long white shaft of tightly wrapped leaves. They store beautifully in the ground — there's no rush to harvest, so you can leave them in the soil and pull them as you need them through autumn and winter.

They're also genuinely easy. Pests largely leave them alone, they tolerate poor weather, and a single sowing can feed you for months.

When to sow

Leeks have a long growing season — roughly 25 to 35 weeks from sowing to harvest — so timing matters.

Northern Hemisphere: Sow indoors in late winter to early spring (February–April), or sow outdoors once the soil has warmed in mid to late spring. Transplant seedlings in early summer for autumn and winter harvests.

Southern Hemisphere: Sow in late winter to spring (August–October).

Because they're slow, leeks reward an early start. If you're reading this in late spring, you can still sow now for a winter crop — just choose a fast-maturing variety. Always check your local last-frost date; young seedlings appreciate frost-free conditions to get established.

Sowing seeds

Sow seeds about 1 cm (½ in) deep in trays, modules, or a seedbed. Keep them at around 15–18°C (59–65°F) to germinate, which takes one to two weeks.

When seedlings reach the thickness of a pencil and about 20 cm (8 in) tall — usually 10 to 12 weeks after sowing — they're ready to transplant. Don't worry if this feels slow; leeks are patient plants and so should you be.

Transplanting: the dibber trick

This is the step that makes leeks special. To get those long, blanched white shafts, you plant seedlings deep into individual holes.

1. Use a dibber (or a thick stick) to make holes 15 cm (6 in) deep and 15 cm (6 in) apart, in rows 30 cm (12 in) apart. 2. Trim the seedling roots and the leaf tips slightly to reduce stress. 3. Drop one seedling into each hole. 4. Don't backfill with soil. Instead, "puddle" them in — fill each hole with water. The soil settles around the roots naturally, leaving an air gap that lets the shaft expand and stay pale.

The deep planting is what blanches the stem, giving you that tender white portion cooks prize.

Caring for your leeks

Leeks are low-maintenance, but a little attention pays off:

Water during dry spells, especially in the first few weeks after transplanting. Aim for consistent moisture rather than occasional soaking.

Earth up (mound soil around the stems) every few weeks to increase the length of the blanched white shaft. Take care not to let soil fall between the leaves.

Feed with a balanced organic fertiliser mid-season if your soil is poor.

Weed regularly — leeks dislike competition, and their upright leaves cast little shade to suppress weeds themselves.

Pests and problems

Leeks are remarkably trouble-free, but watch for:

Leek moth and allium leaf miner: Cover plants with insect-proof mesh in regions where these are a problem.

Leek rust: Orange pustules on leaves, common in damp weather. Improve airflow by spacing plants well, and choose rust-resistant varieties. Mild cases rarely affect the harvest.

Rotate your alliums — don't grow leeks, onions, or garlic in the same spot two years running.

Harvesting

Harvest leeks whenever they reach a usable size, from early autumn onward. Use a fork to gently lever them out rather than pulling, as the shafts can snap.

The beauty of leeks is that they hold in the ground. In all but the harshest climates, you can leave them in the soil and harvest fresh through winter — nature's own refrigerator. In zones where the ground freezes solid (USDA zones 6 and below, or RHS H5+ areas), lift a supply before a deep freeze or mulch heavily with straw.

A few varieties to try

Early types (e.g. 'King Richard', 'Zermatt') — fast, slender, great for late sowings.

Maincrop and overwintering types (e.g. 'Musselburgh', 'Bandit') — thick, hardy, stand all winter.

Share your harvest

Because leeks crop over such a long window and store so well in the ground, it's easy to grow more than one household can use. That's exactly the kind of surplus worth sharing with neighbours — a few leeks swapped for someone else's winter squash makes everyone's table richer.

Ready to grow, swap, and share your homegrown food with people nearby? Join Locavori today and connect with growers in your neighbourhood.