When to harvest purple choy sum

Once the plant is established and bushy — start light and increase as it fills out. Purple Choy Sum is harvested for its leaves, and it responds to being picked — regular cutting keeps it producing tender new growth, while a plant left alone gets leggy, flowers, and turns bitter. Take from the outside or the top depending on how it grows, and never strip it: leave enough leaf behind for the plant to power its regrowth.

Pinch or snip just above a leaf pair or node, which pushes the plant to branch into two shoots. Take no more than about a third at once, and pick from the outer or older growth first.

Use fresh where you can. Otherwise stand cut stems in a glass of water on the counter, or wrap loosely in a damp cloth in the fridge for a few days. Freezing in oil holds flavour far better than drying for most soft-leaved kinds.

Stripping purple choy sum bare in one go, or letting it flower unchecked. Both stall regrowth, and flowering in particular turns the leaves bitter.