Replanting
Replanting
Replanting
Keep your best bulbs to replant. I keep all three sizes to replant the following season - small, medium and large. It has been my observation that:
A large bulb will divide into numerous bulbs of varying sizes (usually a nest of 5-8+ clones).
A medium bulb will divide into two or three bulbs of varying sizes.
A small bulb will grow into one large bulb (and that large bulb will divide numerous times when planted the following season - see bullet point one).
Crop Rotation
It is suggested that you rotate onions in your garden, which helps prevent the accumulation of pests and diseases. I rotate mine every year.
Bulb sizes
Nests of All Very Small Bulbs