How and when to harvest seeds from leeks

Credit: Kowloonese

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Q: How do I go about collecting seeds from my leeks for next year, and when do I start them off?

Considered “the gourmet’s onion,” savoury leeks are a long-season crop best started in flats in March and planted out at 20 cm (8 in.) tall.

Leeks continue to grow through fall and can be harvested anytime through to the next spring. Mulch in cold areas. For tender, white leeks, blanche them by planting in a 15 cm (6 in.) trench, topping up the soil as they grow. Leeks can be a dramatic backdrop in ornamental gardens, and also work well with all vegetables except beans, which are inhibited by the onion family.

Here’s some helpful advice from Carolyn Herriot, our “Zero-Mile Diet” columnist, on harvesting seeds from leeks:

Onions and leeks (Liliaceae family) are biennial plants that set seed in the second year. They are cross pollinated by tiny insects, so to maintain varietal purity it’s important that no other alliums are flowering within 1.6 km (1 mile)! Seeds develop in small inflorescences on large globular seedheads and require patience for ripening, they can take a long time.

TIP: Do the squeeze test before harvesting – if they are squishy they are still maturing. I take leek seedheads that developed around April off around the end of September. I leave them on the top shelf of the greenhouse to thoroughly dry. I then cut the seeds off with sharp scissors and rub them between gloved hands to remove the chaff. The strong onion smell makes my eyes water! These seeds are then screened to remove debris. Allium seeds have a short shelf-life (viability) – one year, two at the most, so it’s good to let some plants go to seed every year.