Answer: Onions prefer to grow in the cooler temperatures of autumn and spring. When the weather gets too hot, they bolt (send up flower stalks), which indicates the plants are putting all of their energy into producing seed, rather than enlarging bulbs. You should always cut any stalks off of onions as soon as they appear. The average days to maturity is about 100. Onions go through a process called `bulbing' to produce the onion bulb. Bulbing is affected by amount of daylight, not by plant age. Daylight necessary to initiate bulbing depends on the variety of onion and can range from 12 hours for early maturing types to 15 hours for late maturing types. You can harvest onions anytime; the longer they remain in the ground, the larger the bulb will be. I'd suggest pulling one of the onions to see how large it is. If it's a good size, you can bend over the tops of the rest of the onions so they will stop growing leaves and begin to enlarge underground. If it's still small, wait a few weeks and pull another one. Eventually they will be the size you expect and you can dig them all and store them for later use.
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