Leek Companion Plants
Vegetable120 days to maturity
Leeks are a slow-growing allium grown for their mild, thick white shanks rather than a bulb, and they tolerate cold well enough to overwinter in many regions. Gardeners blanch the stems by hilling or trenching soil around them to keep the edible base pale and tender. Their main pests are onion-family specialists like onion thrips, leek moth, and the allium leaf miner.
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Companion Planting Strategy for Leek
Like other alliums, leeks give off a scent that deters carrot fly and other pests, so they pair naturally with crops bothered by those insects. They grow happily alongside other alliums and slim-rooted vegetables but should not be planted with legumes, whose growth alliums tend to suppress.
Best Companion Plants for Leek
These plants grow well alongside Leek — providing pest control, attracting pollinators, or making better use of your garden space.
Leeks and carrots are a classic duo because the leek's scent repels carrot fly while the carrot's scent deters onion fly, so each protects the other.
Celery and leeks have compatible cool-season needs and growth habits, and celery's strong aroma helps confuse pests that target alliums.
Onions are close allium relatives with the same soil and water preferences and the same pest defenses, so they grow well together without competing differently.
What Not to Plant With Leek
Keep these away from Leek. They compete for resources, attract shared pests, or inhibit each other's growth.
How to Grow Leek
- Botanical name
- Allium ampeloprasum (Porrum group)
- Family
- Allium (Amaryllidaceae)
- Sun
- Full sun, 6-8 hours daily
- Water
- 1-1.5 inches per week, kept consistently moist
- Soil
- Rich, well-draining loam high in organic matter, pH 6.0-7.0
- Spacing
- 6 inches apart; rows 12-18 inches
- Planting depth
- Sow seed 1/4-1/2 inch deep; transplant into 6-inch holes to blanch the shanks
- Germination
- 10-14 days at 65-75F
- Days to maturity
- 100-150 days from transplant depending on variety
- When to plant
- Start seed indoors 8-12 weeks before the last frost; transplant out around the last spring frost
- Harvest
- Lift when shanks reach about 1 inch thick; dig as needed and harvest hardy types through fall and winter
Common Leek Problems
Leek moth (larvae tunneling into leaves and shanks)
Cover plants with insect netting during egg-laying flights, remove and destroy infested plants, and rotate alliums to a new bed each year.
Onion thrips (silvery streaking and stippling on leaves)
Keep plants well watered to reduce stress, encourage predatory insects, and treat heavy infestations with insecticidal soap or spinosad.
Rust (orange pustules on the leaves)
Space plants for airflow, avoid overhead watering and excess nitrogen, remove affected leaves, and rotate crops since rust overwinters in allium debris.
Allium leaf miner (lines of pupae in stems, distorted growth)
Exclude the flies with fine insect netting during their spring and fall flights, and destroy infested plants rather than composting them.
Leek Companion Planting FAQ
What are the best companion plants for leeks?
Carrots are the classic match because leeks repel carrot fly while carrots repel onion fly, and celery and other alliums like onions share the same needs and pest defenses. Brassicas such as cabbage and members of the carrot family also pair well with leeks.
What should you not plant with leeks?
Avoid planting leeks with beans, peas, and other legumes, because alliums release compounds that suppress the bacteria legumes use to fix nitrogen, stunting both crops. Keep them out of beds where you want strong legume growth.
How do you blanch leeks for a longer white stem?
Transplant seedlings into deep holes or a trench and gradually hill soil up around the stems as they grow, which excludes light and keeps the shank white and tender. Avoid letting soil fall between the leaves, since trapped grit makes them hard to clean.
How long do leeks take to grow?
Leeks are slow, taking roughly 100-150 days from transplant depending on the variety, with winter-hardy types maturing latest. Start seed indoors in late winter so plants have the long season they need.
More vegetable companions
Plan Your Leek Garden
Use our interactive tools to design the perfect garden with Leek and its companions.