Choosing the ideal pepper tree for your garden: our complete buying guide

For the flavour of its berries

Logically, the main reason for buying and planting a Sichuan pepper tree (Zanthoxylum) is to harvest its berries, whose pericarp or aromatic outer layer, bronze-pink to rosy-red when ripe, is dried for consumption. The seeds, which are black, hard and shiny, have a very bitter taste. This outer layer contains a more or less pronounced citrus flavour, ranging from mandarin and lemon to grapefruit and orange, depending on the species and variety. On the tongue, these berries often leave a sensation of numbness and tingling.

If you really want to grow a pepper tree for the flavour of its berries, Zanthoxylum piperitum is certainly the most suitable. This Chinese pepper tree produces red berries with a flavour that is spicy, aniseed and lemony all at once. Harvesting takes place when the red outer layer splits open to release the black seed. Once dried overnight, these outer layers can be used to season soups or dishes based on pork, duck or chicken. The berries of this species are harvested in October. It also forms a large shrub, 4 m tall and 3 m wide, with highly aromatic foliage.

Zanthoxylum piperitum is the species of Sichuan pepper tree with the most aromatic berries

Zanthoxylum schinifolium, also known as Japanese pepper tree or mastic-leaved prickly ash, produces sansho berries. This “mountain pepper”, wonderfully fresh on the palate, has a flavour quite similar to lemongrass, enhanced by notes of mint and woodland. In addition to their hot, peppery and spicy flavour, these berries also have the ability to numb the tongue. They are widely used in Japan, among other things to enhance raw or cooked fish dishes, shellfish and meat. This “pepper” can also be added to a fruit salad or chocolate dessert, thanks to its highly delicate citrus aromas.

For these two pepper tree species, you must wait at least 3 to 4 years before they start fruiting.

One final pepper tree species produces exceptional berries. This is Zanthoxylum armatum, whose berry seed coats are used to produce Timut pepper, with very powerful citrus aromas, particularly grapefruit.

For the aesthetic appeal of the shrub and the beauty of its foliage

If harvesting the spicy, aromatic berries is one of the main attractions of Sichuan pepper, the shrub is also interesting for its ornamental appeal. Growing 3 to 6 m tall and 2 to 3 m wide, Zanthoxylum is a deciduous shrub that is easy to grow in our climate thanks to its hardiness. It is above all the foliage that makes Sichuan pepper so appealing. Alternate leaves are divided into numerous, rather fine and elongated leaflets with toothed edges. Odd-pinnate, the leaves of Zanthoxylum always have an odd number of leaflets. They are highly aromatic, like the berries.

In terms of ornamental appeal, some species of Zanthoxylum stand out. First among them is Zanthoxylum piperitum ‘Black Magic’. As its name suggests, this recently bred hybrid stands out with foliage tinted purplish violet, almost chocolate-brown to very glossy black, and particularly aromatic. Highly ornamental, this variety produces young shoots of a deep black, surrounded by metallic highlights. Later, in summer, the foliage turns green, then changes to orange-red in autumn. This Sichuan pepper also has a bushy, spreading and rather irregular habit, with very fine foliage. Growing 3 m tall and wide, it can be grown in a pot on a large balcony or terrace. Gourmets may regret the absence of berries, which this hybrid does not produce, but its leaves and buds are edible and can be used to accompany salads or fish.

American prickly ash (Zanthoxylum americanum), native to eastern North America, is also a deciduous species of prickly ash. Its leaves are compound and ovate to elliptical, with 5 to 11 leaflets. They are very dark green on the upper surface and lighter underneath. They are also hairy on the underside, as are the young branches. In autumn, the leaves take on a lovely golden-yellow colour. With several stems and many branches, it can be recognised by its broad silhouette.

Zanthoxylum piperitum ‘Black Magic’ and Zanthoxylum americanum are highly ornamental species

Zanthoxylum simulans is also quite ornamental thanks to its unusual verrucate bark. Fine thorns cover the trunk and branches. Over time, they thicken and their tips become blunter. These thorns form protuberances that are quite attractive thanks to their distinctive appearance.

For its cold hardiness

It is undoubtedly the American prickly ash (Zanthoxylum americanum) that boasts the greatest hardiness. While most varieties withstand frost down to -15 to -18 °C, this one stands out for its hardiness down to -25 °C. In other words, it can be grown anywhere in France, in perfectly well-drained soil, even rocky, chalky soil. This species is native to the eastern United States and Canada and grows naturally on cliffs or high-altitude rocky plateaux. It is also highly resistant to pollution and the poor soils found in towns and cities. It will only need a few waterings during periods of intense summer heat or drought.

The Korean prickly ash (Zanthoxylum coreanum) also boasts slightly above-average hardiness. It can occasionally withstand temperatures as low as -20 °C, as well as altitudes of between 700 and 1,000 m, provided it is planted in perfectly well-drained soil. It can also cope with wide temperature fluctuations. This species also has the particular feature of producing very strong thorns on its trunk and branches, coloured orange-red. Highly attractive, these thorns are extremely decorative, especially in winter, when the foliage has fallen.

For its ability to be incorporated into a defensive hedge

The Sichuan pepper tree easily finds its place as a solitary feature in a lawn. Its elegant silhouette, clusters of small red berries and golden-yellow autumn foliage look wonderful there. However, because it has fairly sharp thorns when young, Zanthoxylum should not be planted beside a path frequented by young children or pets. This is why planting it as an informal defensive hedge is an interesting solution.

For use in a defensive hedge, the American prickly ash (Zanthoxylum americanum) seems the most suitable, as it is particularly thorny. This species has the distinctive feature of bearing two thorns beneath each bud. These thorns become blunter and form a sort of wart over time. Suffice it to say that these impressive thorns provide excellent protection against wild animals or ill-intentioned people intruding.

The other species certainly suited to forming a hedge is Zanthoxylum simulans. This prickly ash is armed with particularly formidable thorns. These powerful thorns give it a certain charm in winter, after the leaves have fallen, but they can make harvesting the berries rather difficult! As for the Korean prickly ash, it has red thorns.

The presence of thorns that become blunter over time makes the Sichuan pepper tree ideal for a defensive hedge

These two prickly ashes can be planted alongside other thorny shrubs such as barberry (Berberis), trifoliate orange (Poncirus trifoliata), the blackthorn (Prunus spinosa), firethorn (Pyracantha) or even Japanese quince (Chaenomeles).