These need a long growing season. Plant from November for early summer crops. Or plant in February / March once the soil is workable.
The RHS recommends planting in March. Plant sets on a patch that has been manured for a previous crop, by simply pushing the bulbs into the ground leaving their tips exposed. Space plants 9 inches apart in rows spaced 12 inches apart. Once established shallots rarely need watering. Keep the plot weed free. The crop is ready for harvest once the foliage has yellowed and started to wither – usually towards the end of July. Simply lift the bulbs, split the clumps and spread them out in the sun to dry.
Overwintering shallots: Golden Gourmet AGM; Matador AGM