Your onions are bolting, probably due to temperature fluctuations such as a heat wave or cold spell. It happens to the best of us gardeners. The onions are bolting because they might die and throwing out seed to reproduce before they die. Has it been hot? The only to prevent this is to keep the plants well watered in hot summer especially when heat waves strike. If you try onions next year, remember that seedlings are less likely to bolt compared to bulb onions grown from sets.
Your onions are bolting, probably due to temperature fluctuations such as a heat wave or cold spell. It happens to the best of us gardeners. The onions are bolting because they might die and throwing out seed to reproduce before they die. Has it been hot? The only to prevent this is to keep the plants well watered in hot summer especially when heat waves strike. If you try onions next year, remember that seedlings are less likely to bolt compared to bulb onions grown from sets.