Houttuynia cordata, Chinese Pepper: Planting, Growing

Description and botany

Houttuynia cordata, also known as “Coriander of the woods” or “Chinese pepper”, is a perennial groundcover plant belonging to the Saururaceae family, classified within the order Piperales like pepper plants, peanuts and wild ginger. Its unpronounceable name originates from the famous Dutch botanist, Marteen Houttuyn.

Houttuynia cordata is the only species represented in its genus. It comes in several varieties with variegated foliage or double flowers. Native to China and Japan, it grows naturally in wetlands and marshy areas where it spreads through numerous creeping underground rootstocks. This is why it’s considered a semi-aquatic plant that can grow in shallow water and waterlogged soils by riversides, banks or water plants.

This creeping perennial slowly forms a carpet of leaves reaching 30 to 40 cm in height and spreads up to 50 cm wide at ripeness through its rhizomatous roots. Its rootstocks are fragrant and edible. They have a peppery flavour much appreciated as a vegetable or condiment in Asian cuisine for flavouring dishes.

Houttuynia cordata, as an effective groundcover, quickly fills out by rooting from place to place, with no theoretical limit to its expansion if conditions are favourable. The species can therefore sometimes become invasive in areas that remain moist throughout the year. A quality that makes it useful for stabilising riverbanks.

In spring, the stems develop delicate deciduous foliage, semi-evergreen in mild climates, highly ornamental. The leaves unfold into fleshy, aromatic laminas. They are leathery, petiolate, quite broad and cordate (shaped like an elongated heart). They are dark green with bronze highlights or greyish-green with prominent veins. Houttuynia cordata ‘Chameleon’ stands out with its beautifully variegated leaves in cream, yellow, pink and green, as colourful as a little chameleon! When crushed, they release a scent of orange bark with a slight peppery note. Its highly aromatic young leaves are used in Asian cuisine to flavour dishes or accompany spring rolls, hence its vernacular names “Coriander of the woods” or “Chinese pepper”.

The plain foliage of Houttuynia cordata, with colourful varieties on the left, ‘Chameleon’ in autumn (© Leonora Enking) and ‘Tricolor’ (© Andrey Zharkikh)

In summer, from June to August, small spikes of immaculate, fragrant flowers dot the foliage. The flowering takes the form of conical inflorescences: the green-yellow flowers are surrounded by 4 large white bracts. They resemble dogwood flowers. ‘Flore Pleno’ is a cultivar distinguished by its very double, pagoda-like flowers.

Houttuynia cordata is a common plant in Asian pharmacopoeia where it’s used for its detoxifying, diuretic, antibacterial and antiviral properties contained in its roots. It notably treats breathing disorders.

The lovely white flower of Houttuynia cordata, close-up on the left and flowering like a constellation in the middle. On the right, the double-flowered variety ‘Flore Peno’ (© Andrey Zharkikh)

Main species and varieties

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Planting Houttuynia cordata

Where to plant it?

It is hardier than you might think! Resistant to cold down to -15°C, houttuynia can be grown in most regions, only fearing severe frosts especially if prolonged. Its foliage may remain evergreen in mild climates. As an aquatic marginal plant, it appreciates good moisture levels. Cultivation will be more demanding in Mediterranean climates, requiring frequent watering due to summer dryness and heat. It needs consistently moist to wet soil, rich in humus. In fact, any good soil that remains sufficiently moist, even clay, will suit it. Its roots tolerate being partially submerged under a few centimetres of water but be cautious as they will be more vulnerable to frost in colder regions. In harsher climates, it may not withstand severe frosts, which is why in these areas it’s preferable to grow it in a perforated aquatic planting basket to be stored in winter in a bright, frost-free room.

This plant dislikes scorching exposures. Plant it in full sun in regions north of the Loire or in partial shade elsewhere. In a partially shaded and cool summer spot, for example, it will form spectacular, generous leafy tapetums. It may tolerate sun if planted in consistently moist soil. The ‘Chameleon’ variety however prefers sunny damp areas to maintain its leaf coloration; too dense shade would limit its multicoloured variegation.

It thrives in shaded borders, along permanently damp paths, at woodland edges, and even in containers where the soil must be kept constantly wet. In the dry shade of trees and bushes, it will be less invasive, which can be useful if you wish to control its spread.

A beautiful damp area border featuring Houttuynia ‘Chameleon’, some Water Lilies, Scabious, Plectranthus and Cannas (© Cultivar 423)

When to plant houttuynia?

Houttuynia is best planted in spring when all risk of frost has passed.

How to plant it?

In open ground

Ensure the plant never lacks water. Allow 3 to 4 young plants per m² to form a beautiful leafy cover.

• Loosen the soil well and dig a hole 2 to 3 times the volume of the root ball
• Plant in the centre of the hole in a mixture of garden soil and rich compost
• Backfill then gently firm with your foot
• Mulch around the base with organic mulch to retain moisture
• Water thoroughly after planting and very regularly to keep the soil constantly moist

In containers

Choose an unperforated zinc pot or basin at least 50 cm in diameter.

• Plant the root ball in compost with water retentive granules
• Water to keep the growing medium constantly moist
• Bring the container under cover in autumn in cold regions

→ Learn more about growing Houttuynia in pots with Gwenaëlle’s advice

Care and Maintenance

Houttuynia cordata grows without requiring particular attention as long as it remains in consistently moist soil throughout the year.

This groundcover cannot tolerate dryness: whether in pots or in the ground, ensure the substrate remains constantly damp, and water accordingly, especially during hot, dry weather. The soil should never dry out completely between waterings.

If grown in a container, you must be able to meet its water needs.

Apply an organic mulch (straw, dead leaves, etc.) to reduce evaporation in summer and protect its rhizomatous roots from frost in winter, particularly in colder regions.

Each spring, add a little compost around the base by lightly scratching it into the surface.

It can become invasive, especially in marshy ground: to control its spread, regularly remove suckers.

⇒ Discover the right techniques for planting a perennial correctly in our video!

Propagation

While Houttuynia cordata easily naturalises on its own through underground rootstocks, dividing the clump is an excellent way to propagate this ground cover. Carry out the process in spring.

1. Using a spade, lift a portion of the stump
2. Divide it into several sections, each containing rootstocks
3. Replant the rootstock sections immediately, either in pots or directly in the ground
4. Keep the soil consistently moist to wet

Pair with

With its foliage in solid or variegated hues, Houttuynia cordata is an essential ground cover to brighten up cool, damp areas of the garden. Along with Pachysandra and Asarum, it creates lovely tapetums of leaves at the base of bushes or deciduous trees in shady corners.

At the edge of a partially shaded border, it will complement Hosta tardiana ‘Halcyon’, a Dryopteris affinis and a Pachysandra terminalis, as well as the delicate flowering of Barrenworts and periwinkles. It can be paired with spring-flowering bushes such as magnolias, deutzias, spireas, lilacs, and flowering crabapples.

In a water garden, it will fill out the base of other perennial marginal water plants like Acorus, astilbes, sedges, lady’s mantles, and marsh spurges.

Houttuynia cordata beautifully paired with lady’s mantles, Acorus gramineus ‘Oron’, Astilbes, and Carex oshimensis ‘Everillo’

→ Discover more companion planting ideas for Houttuynia in our advice sheet!