Plant onion sets in a sunny, open position in fertile, well-drained soil from mid-March to mid-April, spacing them 15cm (6in) apart in rows 30cm (12in) apart, with the tips just showing above the soil surface. Firm the soil around each set after planting to help prevent movement and protect against frost heaving.
Avoid planting in freshly manured ground, and grow onions in a different area each year where possible, avoiding beds that have recently grown onions, garlic, leeks or other alliums to help reduce the risk of pests and diseases.
Keep the soil free from weeds and water during prolonged dry spells while the bulbs are swelling, but avoid overwatering as the bulbs mature.
Lift the onions once the foliage begins to yellow and flop over, usually around August, then allow them to dry thoroughly in a warm, airy place before storing. Store only fully ripened, healthy bulbs in nets, trays or plaits in a cool, dry, frost-free location for use throughout autumn and winter.
Plant shallot sets in full sun in fertile, well-drained soil from September to February, spacing them 15cm (6in) apart in rows 30cm (12in) apart, with just the tip of each set showing above the soil surface.
Avoid freshly manured ground, and for the healthiest crop, plant in a different area of the garden each year, avoiding sites where onions, garlic, leeks or other alliums have grown within the last 3-4 years.
Keep the area free of weeds and water during dry spells while the plants are actively growing, reducing watering as the bulbs begin to mature. Lift the shallots once the foliage turns yellow and starts to die back, then leave the bulbs to dry thoroughly in a warm, airy place before storing them in a cool, dry, frost-free location.