Leeks (Allium ampeloprasum var. porrum) are closely related to chives, garlic, onion and shallots and are mainly grown on sandy soils of the Swan Coastal Plain near Perth. They originated in the Mediterranean area and have been cultivated for up to 4000 years.
Leeks are grown for their thickened cylindrical ‘stem’ or shank which is made up of long leaf bases. They are biennial, but are grown as a short-lived annual for retail markets.
Leeks are not a preferred crop for many growers because plants spend 8 to 16 weeks in the nursery or seedbed before transplanting, then take 21 to 30 weeks to reach maturity. Two crops can be grown in a year and some growers crop consecutively, as there is less build-up of soil diseases compared with other vegetables. Highest yield and quality come from growing leeks in rotation with other types of vegetables.
Leeks are mainly used to flavour soups and casseroles and can also be used raw in salads. They are a good source of vitamins, minerals and fibre.
They grow best with temperatures between 15 and 25°C. It is difficult to produce good quality in hot climates. Although quite frost tolerant, they may flower (‘bolt’) in spring following low winter temperatures. They will grow on a range of soil types, but well drained neutral to slightly alkaline soils are preferred.