Regrowing green onions

What it is

A green onion you bought once can feed you for weeks. Cut off the green tops to use, leave the white root ends in a glass of water on the windowsill, and they grow back, again and again, from the same bulb you already paid for.

Regrowing green onions is the practice of taking the root ends of spring onions, also called scallions, and growing fresh green shoots from them in water or soil. It is the simplest entry point into regrowing food from kitchen scraps because green onions regrow fast, reliably, and visibly, often producing usable new growth within a week. The root base contains the energy and growing point needed to push out new green tops as long as it stays alive.

The method could hardly be easier. You keep the bottom few centimetres of the onion with the roots intact, stand them root-down in a small glass with enough water to cover the roots, and place them on a sunny windowsill. The greens regrow quickly, and changing the water every couple of days keeps them healthy. For longer-lived plants, the roots can be potted in soil, which sustains them far longer than water alone. Most people start with water because it is free and the regrowth is satisfying to watch. The honest trade-off is that water-grown onions weaken after a few harvests as they exhaust their reserves, so soil is better for the long term. But getting several free harvests from a single bunch is a small, genuine pleasure.