A red onion to look out for is ‘Electric’, which has a sweet flavour and deep-red skin. Of the golden-skinned varieties, ‘Summer Gold’ can be stored for up to four months. ‘Swift’ has a mild flavour and ‘Radar’ is superb when eaten fresh. Good Japanese sets are ‘Keepwell F1’ and ‘Senshyu’.
Autumn-sown onions will be in the ground for about 42 weeks. Choose a sunny patch with free-draining soil that has been dug over and raked flat. Aim for a loose texture: too firm, and the roots will push the onion out of the ground. Plant the bulbs 4in apart in rows that are 6in apart, burying the bulb so the tip is level with the surface, and firm the soil around it. If the growing area is limited, plant an inch apart — you will get smaller onions, but they will be just as delicious.
Birds sometimes pull the green shoots out of the ground. If this happens, loosen the soil with a trowel and replant the bulb, taking care not to damage the roots. You could cover them with a cloche or fine mesh. In an Indian summer, water only until established, as onions do not need a huge amount.
Harvest in May or June when the leaves have turned yellow, using a fork to loosen the soil. Lift out the onions, laying them on the soil to dry. This will take 10 days to three weeks. When the skin is crisp and papery, the onions will be ready for storing.
If rain is forecast, dry indoors on newspaper. Store in net bags or trays, or plait into a rope. They should be used soon after harvesting, as they store less successfully than spring-sown varieties.
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The Organic Gardening Catalogue, 01932 253 666, www.organiccatalog.com; Marshalls, 01945 466 711; Mr Fothergill’s Seeds, 01638 552 512, www.mr-fothergills.co.uk