Where possible, choose onion sets that have been heat-treated. This means their flower embryos have been killed, so they're less likely to run to seed or bolt. Generally, growing onions from sets ...

Onions are a kitchen staple that can be planted in either spring or autumn and are easy to grow in a sunny spot. The Which? Gardening experts have grown and tasted onions from sets (little bulbs), ...

As long as you get the basics down, growing them in containers outdoors can be simple yet rewarding. Green onions have small root systems, so a container that's about 6 to 8 inches deep is ideal.