ABSTRACT
This chapter emphasizes developments in onion culture in temperate regions. As much as possible, reference is made to scientifically conducted trials and comparisons, upon which cultural techniques are increasingly based. Temperate regions, being at fairly high latitudes, have long photoperiods during the summer months. Consequently cultivars requiring a long photoperiod for bulbing, frequently termed “long daylength cultivars” predominate. Within temperate regions onions are grown both to harvest as green shoots for salad use and to harvest as bulbs. The desired marketable product largely determines the cultural techniques that are appropriate. Bulb onions can be grown on a range of soils from loams with some clay content to quite light sands. In cold climates green salad onions are produced for winter and early spring production by planting mature storage bulbs side-by-side in a glasshouse or cold frame. In Britain a minor industry and much amateur effort is devoted to the production of giant prize winning onion bulbs.
