I once found an onion in the back of my pantry that had grown a six-inch green stalk through the top of the bag. It looked like a science experiment. I was not proud of this.

Onions seem indestructible — they are tough, they have layers, they make you cry. But they go bad faster than you think if you store them wrong. Here is what I changed, and why my onions now last a full month without sprouting or going soft.

Keep Onions Away From Potatoes

This is the number one mistake. Potatoes and onions are best friends in the kitchen but enemies in storage. Potatoes release moisture and ethylene gas, and that gas makes onions sprout. Onions also release gas that makes potatoes sprout. Storing them together speeds up spoilage for both. Give them separate baskets on opposite sides of the pantry. At least a few feet apart.

Dark, Cool, and Breathable

The ideal onion storage spot is dark, cool (45–55°F), and dry. A basement or cool pantry corner works. The container matters too — mesh bags, open baskets, or paper bags with holes punched in them. Anything that lets air circulate. Those plastic net bags onions come in from the store? Keep using them. They are designed for this.

Do not put whole onions in the fridge. The cold, humid environment turns them soft and mushy. The only exception is if you live somewhere hot and humid with no cool storage — then the fridge is better than the counter, but use them faster.

Check Once a Week

One bad onion really does spoil the bunch. If one starts to rot, the moisture and mold spread to its neighbors. I spend thirty seconds once a week squeezing each onion. Firm is good. Soft anywhere means use it tonight. Any sign of mold — toss it immediately and check the onions next to it.

Cut onions are a different story. Once sliced or diced, they go in an airtight container in the fridge and should be used within three days. The smell gets stronger and the texture goes downhill fast after that.