Disease & Pests: Botrytis blast and downy mildew are common leaf diseases. One starts with white spots and streaks, the other with purple-grey areas on leaves. Leaves wither from the top down and plants die prematurely. Separate the overwintered and spring crops because disease starts in older plants and moves to younger. Avoid overhead watering and plant in open sunny locations. Use lots of compost and practice strict sanitation and crop rotation.
Companion Planting: The pungent odour of onions repels many pests and also protects nearby garden vegetables. Plant chamomile and summer savory near onions to improve their flavour. Onions also work well alongside beets, Brassicas, carrots, dill, kohlrabi, leeks, lettuce, strawberries and tomatoes. Don’t plant onions near asparagus, or peas of any kind.