Zanthoxylum piperitumJapanese Pepper

Zanthoxylum piperitum is the source of sansho, the citrus-sharp Japanese seasoning made from its split red husks. Japanese Pepper is a slow deciduous shrub of Japan, Korea and northern China, with finely divided aromatic leaves, paired spines at the nodes, and a clean structure that has made it a long-standing bonsai subject.

In the ground it is planted as a culinary hedge and a courtyard shrub, where the leaf scent released on brushing past is as much the point as the crop.

Specifications

• Height2 to 4 metres, occasionally to 5 metres
• Width1.5 to 3 metres
• Native toJapan, Korea and northern China
• FoliageAromatic pinnate leaves with small glossy leaflets, turning clear yellow in autumn; deciduous
• Growth rateSlow to moderate

Conditions

• SoilPrefers free-draining, humus-rich soils and dislikes waterlogging
• LightFull sun to partial shade
• WaterModerate; regular through the growing season
• ClimateThrives in warm temperate and cool subtropical regions and is reliably frost hardy

Additional Features

• FlowersSmall yellow-green flowers in spring, with male and female flowers borne on separate plants
• FruitSmall red husks that split to release a black seed, the husk being the source of sansho pepper
• UsesIdeal for culinary and ornamental hedging, courtyard and container planting, and bonsai
• SpacingPlant 1 to 1.5 metres apart for a hedge
• Low MaintenancePrune in winter to keep the frame open; note the paired spines at each node and site the planting back from paths
• Pest ResistanceGenerally sound, with citrus swallowtail caterpillar the usual visitor
• Cultural SignificanceOne of the fundamental seasonings of Japanese cooking, used since well before the introduction of chilli
• Frost ToleranceFully hardy and needs a cold winter to perform at its best

Japanese Pepper is a productive and aromatic hedge for cool-winter climates, and a fine bonsai subject in its own right.