Companion Planting: Leek

Allium ampeloprasum

Spacing: 9 per square foot. Mature height: 1-2 ft.

Plant these nearby

• Carrot: Same allium/carrot pest-masking effect measured for onion and carrot (Uvah & Coaker 1984) — a real, peer-reviewed field study, not folklore. (source)

Keep these apart

• Bush Beans: Alliums are traditionally kept off legume beds on the theory that they inhibit nitrogen-fixing bacteria, but WSU Extension's review of companion-planting research found no scientific basis for that specific mechanism — treat this as garden tradition, not measured evidence. (source)
• Pea: Alliums are traditionally kept off legume beds on the theory that they inhibit nitrogen-fixing bacteria, but WSU Extension's review of companion-planting research found no scientific basis for that specific mechanism — treat this as garden tradition, not measured evidence. (source)

Common pairings, answered directly

Can I plant leek next to carrot?

Yes. Same allium/carrot pest-masking effect measured for onion and carrot (Uvah & Coaker 1984) — a real, peer-reviewed field study, not folklore.

Can I plant leek next to bush beans?

Better not to. Alliums are traditionally kept off legume beds on the theory that they inhibit nitrogen-fixing bacteria, but WSU Extension's review of companion-planting research found no scientific basis for that specific mechanism — treat this as garden tradition, not measured evidence.

Can I plant leek next to pea?

Better not to. Alliums are traditionally kept off legume beds on the theory that they inhibit nitrogen-fixing bacteria, but WSU Extension's review of companion-planting research found no scientific basis for that specific mechanism — treat this as garden tradition, not measured evidence.

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Companion planting for Leek: which plants to grow next to it, which to keep apart, and the reason behind each pairing.

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