Horseradish is a common sight in the wild in Ireland if you know where to look. It's a perennial from the Brassica family, with a long tap root and very eager to spread - keep this in mind when you plant it. The large bright-green leaves resemble those of dock, and in early summer it will bear small white flowers in panicles. The root is edible, with a lovely sharp taste (it is known as barbaforte, 'strong beard', in some parts of Italy), used to make horseradish sauce. A good addition to the kitchen garden - consider growing it in deep containers to control its vigor.

Site: Tolerates exposure
Soil: Any well-drained
Position: Full sun to part shade
Season of Interest: Edible roots
Hardiness: Fully hardy
Height: 3ft (1m) Spread: up to 1.5ft (0.5m)