GROWING LARGE ONIONS FOR EXHIBITION AND COMPETITION IN THE UK

Growing vegetables for either maximum size (weight) or perfect appearance is a popular hobby in the UK. Competitions at local vegetable shows for the largest vegetables, including onion bulbs, date back to the 1800s and were particularly popular in industrialized areas associated with coal mining and heavy engineering. The largest onion is judged by weight after cleaning and removing foliage to leave 5 cm of ‘neck’. The onions must be smooth with an entire skin, no basal splitting or doubling at the neck. Seed companies have been selling ‘competition’ cultivars since the late 1800s. In 1892 ‘Ailsa Craig’ was a prize winner at 0.91 kg. In the early 1900s ‘Robinson’s Mammoth’ was introduced and in 1951 ‘Kelsae’. Breeders continue to make selections for larger bulbs, among these is ‘Ailsae’ (pictured). Meanwhile, particularly in the last 40 years, new techniques have been used by innovative growers. Prize-winners nowadays sow their seeds at (18-21°C) in early December or even sooner, and grow seedlings under lamps, ideally in a growing-room at 20°C. The best plants are selected around 21 March and planted into soil-beds in well-ventilated polythene houses where temperatures can be maintained below 25°C, and which can shelter the foliage from damaging wind, rain or hail. Planting at 60 cm between plants (2.8 plants/m²) is suitable, ideally with the soil warmed to 15-18°C. White polythene under the plants is used to reflect light. Free-draining soil-beds are prepared in the autumn, often by alternating layers of soil with well-rotted organic matter. Care must be taken to avoid soil salinity developing. As they grow, leaves are supported by hoops to prevent them folding downwards. Watering and fertilizers are used to maintain uninterrupted growth and any pest or disease problems are treated quickly. Some growers now use CO₂ supplementation. By late June potentially winning onions have 19-20 leaves, a firm neck and a bulb circumference around 65 cm. The National Competition for the heaviest trimmed onion started in 1975. In the late 1970s winning bulbs weighed about 2.25 kg with a diameter of around 16 cm. In the last five years winning bulbs weigh about 6.8 kg with a diameter of about 24 cm. The current world record was established in 2005 at 7.495 kg.