Article: Mature onions may spoil in the cool fall temperature, so harvest them before the first frost. If you planted the onions in the spring, they should be ready in the summer. You can harvest and eat your onions at any phase of their growth, but they'll be larger if you wait until the end of summer when they're fully mature. Target onions with flowers on top first because they will rot if left in the ground. Onions that form flowers don't store well and must be used within 3-4 days. When an onion plant grows flowers, it's a sign that the onion has stopped growing and the plant is now focusing its energy on the flowers. The growth of flowers on the top of an onion is known as "bolting" and is often seen as undesirable to onion growers. You do not have to go through the curing process for onions that have grown flowers. Most onion plants will ripen sometime in the late summer. When the green foliage of the onion plant falls over on its side and turns yellow or brown, it's a good sign that the onion is ready to be harvested. Use a spade to carefully dig a circle, 1 inch (2.5cm) around the bulb. Dig around and under the bulb and sever the roots of the onion. Do not cut the onion with the spade because it will cause the onion to rot prematurely. Firmly grab the base of the green leaves and pull up to extract it from the ground. Loosen the soil with the spade more if you're having trouble getting it out of the ground. Handle onions carefully so that you don't bruise them. Bruising will cause rot.

What is a summary?
Harvest your onions in the late summer before it gets cold outside. Pull onions that form flowers immediately. Wait for the green foliage to fall over if there are no flowers. Loosen the soil around the onion. Pull up on the plant's neck to uproot the onion.