UC Master Gardeners, Santa Clara County, CA
University of California
UC Master Gardeners, Santa Clara County, CA

Leeks

Garden Help > Vegetables

UC Links

How to grow: Growing Onions & Leeks, Center for Agroecology and Sustainable Food Systems (CASFS), UC Santa Cruz

Pest management: Leeks are subject to similar pests and diseases as Onion and Garlic

The Basics

Leeks are members of the Allium family that do not form bulbs like their onion and garlic relatives. Instead, they develop a 6–10 inches edible stem that can be up to 3 inches diameter.

When to plant

  • Transplant August–September
  • To grow your own transplants from seed, start them 10–12 weeks earlier.
  • Leek seedlings are relatively easy to separate so transplants can be grown densely in pots.

Harvest window: Harvest at desired size: ½–1 inches diameter for baby leeks, 1–2 inches for mid-size, or 2–3 inches for full size. Large ones generally require 100-120 days to mature.

Care overview

  • Plant baby leeks 1-2 inches apart, mid-size leeks 4–8 inches apart, and full size 8-10 inches apart
  • For long blanched shanks, plant seedlings in a hole up to the first leaf.
  • For additional length, plant seedlings at the bottom of a V-shaped trench. Fill in the trench and hill soil up around the stems as they grow.

Recommended Varieties for Santa Clara County*

Carentan, OP Long, thick leek grows strong and vigorously, with a delicate and delicious flavor. Up to 2 inches across. An old European heirloom variety. 18–24 inches tall. Plant 4–6 inches apart 

* Many other varieties may also do well here in Santa Clara County. This list is based on UC Master Gardener trials, taste tests, and feedback from local growers.

 
 
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