I grow 4 forty foot rows of onions, garlic and shallots each year. I rotate my crops, in the autumn, when my potatoes are cleared I prepare the ground for my onions by adding manure/compost available free at my site. I dig this in along with some Blood Meal (onions I find do better with lots of nitrogen). In August I sow seeds of Japanese winter varieties which I transplant and then plant in my prepared bed in January/February. I also then plant sets of onions in February/March. I bend over the stems of the earlier Japanese onions in late June and lift them and them dry two weeks later. The same with the set onions but about two months later in late August/September.
To recap in order - August, sow winter onion seeds; September, prepare bed; October, sow garlic cloves and Japanese winter onion sets; November, transplant Japanese winter onion seedlings; January/February plant out Japanese winter onion seedlings; March, plant out main crop sets; June/July, bend over and lift Japanese Onions; September/October, bend over (if needed) and lift main crop onions.
By lifting I mean to just lift the onions from the soil, leave for a fortnight then place somewhere warm and dry to dry before storing in sacks or in ropes.
Use the Japanes ones first. Make sure they are physically dry and keep in a fridge or cool place until needed, they should keep for about a month.
Main crops when dried as described I find keep until early summer, when you have the Japanese ones to take over.
