Stopping and topping

Once a plant starts to flower and set seed it switches its energy away from making leaves, and the leaves it does have often turn bitter, tough or sparse. Taking off the flowering stem, or topping the plant before it gets that far, tells it to keep producing fresh, tender leaves instead of running to seed. This keeps a leafy crop in useful harvest for weeks longer and, on herbs, delays bolting and encourages bushier growth. It also stops the plant self-seeding around the plot if you do not want more.

When

Through the growing season, mainly from late spring onwards, as soon as you spot a flower stem or seed head starting to push up from the middle of a leafy plant. Sorrel and Swiss chard tend to run up in warm, dry summer weather, so keep checking from June through to August. On soft herbs such as basil, mint and coriander, start pinching out the growing tips early, well before any flower buds show, and keep at it every couple of weeks.

How

Basil and other soft herbs: pinch out the growing tips regularly to keep plants bushy and delay flowering. Sorrel, chard and other leaf crops: snip out any flower stem as soon as you see it, so the plant keeps making fresh leaves.

Notes

This buys time rather than stopping bolting for good. Once a plant is set on flowering in a hot, dry spell, repeated stopping only holds it back so far, and a chard or sorrel plant that has bolted hard is best pulled and resown, or left to flower for the bees. Keeping plants well watered and picked often delays bolting in the first place. If you actually want seed, flowers or something for wildlife, just leave a few stems to run. Sorrel is a perennial, so cutting the whole clump right back also triggers a fresh flush of young leaves.