The bulb gets its food from the leaves, so one needs to wait until the leaves brown (and are no longer providing food) before harvesting the bulb, or the bulb won’t reach its full size.
If a flowering stalk appears, however, you can cut off that green stem. Unfortunately though, if an onion bolts (forms flowers) the first year, it will no longer focus on bulb growth, even if one removes the flowering stem. It is best to immediately harvest an onion that has bolted, as the longer it sits in the soil, the more chance its flavor and texture may change and rot may occur. However, you can leave the bulb in the soil for a few days, if needed, before harvesting.
The bulb gets its food from the leaves, so one needs to wait until the leaves brown (and are no longer providing food) before harvesting the bulb, or the bulb won’t reach its full size.
If a flowering stalk appears, however, you can cut off that green stem. Unfortunately though, if an onion bolts (forms flowers) the first year, it will no longer focus on bulb growth, even if one removes the flowering stem. It is best to immediately harvest an onion that has bolted, as the longer it sits in the soil, the more chance its flavor and texture may change and rot may occur. However, you can leave the bulb in the soil for a few days, if needed, before harvesting.
Hope this helps!