Toona sinensis or Chinese Mahogany: Planting and Growing

Botany and description

The genus Toona, encompassing several species of which the most well-known is Toona sinensis, belongs to the Meliaceae family. This genus comprises five species and is distinguished by its wide geographical distribution, ranging from Southeast Asia to Australia.

• Toona calantas or Philippine Mahogany
• Toona ciliata or Australian Red Cedar (synonym: Toona australis)
• Toona febrifuga or Vietnamese Mahogany
• Toona sinensis or Chinese Mahogany (or Chinese Toon): hardy down to -15°C
• Toona sureni or Indonesian Mahogany

The scientific name of the genus Toona derives from its native Australian name. Toona species are mainly distributed across Southeast Asia, India, Australia and some Himalayan regions. Toona sinensis, or Chinese Mahogany, the only species cultivated here due to its hardiness, originates from China and East Asia. There is some confusion regarding the naming of this tree, referred to in various sources as Toona sinensis, Cedrela toona or Cedrela sinensis. However, the genus Cedrela, exclusively American, is now separated from the genus Toona, which originates from the Old World.

Toona sinensis on the left (© Forest and Kim Starr). On the right, Toona ciliata (© Dinesh Valke)

Trees of the Toona genus display a majestic and slender silhouette, with an often upright habit and rounded crown. Mature size can vary considerably between species, but some specimens of Toona sinensis can reach up to 25 metres in height. Toona sinensis is notably known for its relatively rapid growth, particularly in its early years. By the age of ten, it can reach 6 to 8 metres in height.

The bark of Toona trees is generally smooth in young specimens, becoming rougher and fissured with age. Its colour varies from grey to brown.

The foliage is one of the most remarkable aspects of the Toona genus. The leaves are typically large, pinnate (they are compound with numerous small leaflets arranged on either side of a central axis or rachis) or bipinnate, measuring up to 60 cm long. They consist of numerous small oval leaflets, dark green on top and lighter underneath. In autumn, the leaves of Toona sinensis transform into a vibrant colour spectacle. They transition from deep green in summer to a range of spectacular autumnal hues, from golden yellow to bright red, through shades of orange and copper.

The leaves display magnificent colours throughout the year

Trees of the Toona genus produce small white or pink flowers, clustered in racemes or panicles. The flowering of Toona sinensis in particular occurs between May and June. The flowers of Chinese Mahogany are small but appear in large quantities. They are typically white, cream or sometimes slightly pinkish in colour. Each flower consists of five delicate petals and numerous prominent stamens. These flowers are grouped into long panicles or clusters that can reach several dozen centimetres in length. These pendulous clusters give the tree a highly ornamental appearance when in full bloom. One of the most remarkable aspects of Toona sinensis flowering is its fragrance. The flowers emit a sweet, pleasant aroma, often described as subtly honeyed. This scent attracts various pollinators, including bees and butterflies, which is essential for the tree’s pollination. When the tree is in full bloom, it transforms into a spectacular mass of white flowers, creating a striking contrast with its dark green foliage.

Left: flowering of a Toona sinensis (©Fanghong -Wikimedia Commons); right: Toona ciliata (© Dinesh Valke)

The fruits of Toona are woody capsules that open to release numerous small winged seeds. These seeds are dispersed by wind, facilitating the natural propagation of the species.

Toona species typically prefer well-drained, fertile soils, though some can tolerate a variety of soil types, including less fertile soils. Their root system is adapted to efficiently exploit water and nutrients. The root system of Toona sinensis is generally extensive and robust, adapted to support its large size and height. It features a mixed root system, combining deep taproots for stability and anchoring, with widespread lateral roots for efficient water and nutrient absorption.

The most well-known species and varieties

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Planting Toona sinensis

When to plant?

Autumn planting is often considered ideal, especially in temperate climates. Planting during this period allows the tree to establish itself during the cool, damp autumn months before entering winter dormancy.

Early spring, after the last frost, is also a good time to plant Toona sinensis. However, it’s then important to ensure adequate watering during the summer months for young plants.

Where to plant?

Chinese Mahogany prefers a sunny or partially shaded location. Sufficient sunlight is important for the tree’s growth and the vibrancy of its foliage colour, especially for varieties with coloured leaves like the ‘Flamingo’ cultivar.

Well-drained soil is essential to avoid root rot problems. Chinese Cedar adapts to a variety of soil types but thrives best in rich, fertile soil. If your soil is heavy or clayey, it may be necessary to improve drainage or add compost to enhance soil structure. Soil pH matters little to it, tolerating slightly acidic, neutral, or even slightly alkaline soils.

Please note: Avoid planting Toona sinensis too close to drainage systems, septic tanks, or water lines, as its roots can spread extensively and cause issues.

The beautiful autumn colours of Toona sinensis

How to plant?

• Dig a hole twice as wide as the root ball and as deep as the container the tree came in.
• Enhance the removed soil with compost or well-rotted manure if needed, especially if the soil is poor.
• Carefully remove the tree from its container. If the tree is delivered with a root ball wrapped in burlap, loosen the burlap at the collar and plant it without disturbing the root ball.
• Place the tree in the hole so that the top of the root ball is level with the surrounding soil.
• Fill the hole with the amended soil, lightly firming to eliminate air pockets.
• Water thoroughly to help establish contact between the roots and the soil.

Important! : A well-established tree will withstand short frosts in the order of -12 to -15°C. During the first winters, install a thick winter fleece if very low temperatures are forecast.

Care of Toona sinensis

Regular watering is essential, especially during the first few years and in periods of drought, ensuring the soil remains moist but not waterlogged. It is recommended to apply an organic mulch around the base to retain moisture and control weeds.

Pruning is generally unnecessary, except to remove dead or misplaced branches, and should be carried out in late winter or early spring.

Diseases and parasitic pests

The Toona genus cedars are generally resistant to diseases and parasitic issues. However, Toona sinensis may occasionally suffer from aphid or scale insect infestations, which can weaken the tree and reduce its vigour. Fungal diseases such as root rot or powdery mildew may also develop, particularly in poorly drained soil or excessively humid conditions.

Propagating a Toona

The most effective method to propagate Toona sinensis is by sowing. The seeds should be harvested at ripeness, typically in autumn, and can be sown immediately or after cold stratification if stored. To optimise germination, the seeds should be planted in a well-drained substrate and kept in moist but not waterlogged conditions. The ideal temperature for germination is around 20°C. The young plants require careful attention until they are robust enough to be transplanted to their final location.

Caution: To faithfully propagate a variety like Toona sinensis ‘Flamingo’, it is preferable to use vegetative propagation methods such as propagation by cuttings or better still grafting rather than sowing.

Association

To enhance your Toona sinensis ‘Flamingo’, consider a setting composed of bushes and perennial ground covers that offer a harmonious contrast of textures and colours while sharing similar cultivation requirements. In acidic soil, bushes such as azaleas or rhododendrons, with their vibrant flowering in shades of white, pink or purple, will complement the pink hues of the Toona.

For ground cover, opt for perennials like hostas with their fleshy leaves, which will thrive in the partial shade of the Toona, while providing a strong contrast in terms of colour and leaf shape, particularly with Hosta ‘Halcyon’. Also consider a carpet of lesser periwinkle ‘Elisa’ (Vinca minor ‘Elisa’) with their delicate flowers offering a gentle harmony with the pink foliage of the Toona. Here and there, heucheras for their colourful foliage, perhaps pink in the case of the variety ‘Wild Rose’, in rounded clumps, would provide interesting texture and a palette of autumn colours throughout the year. Dwarf asters will add a touch of bright colour late in the season with their generous flowering.

In the centre Cedrela sinensis ‘Flamingo’ (© Leonora Enking), surrounded by Vinca minor ‘Elisa’, Heuchera ‘Wild Rose’, a Rhododendron ‘Roseum Elegans’ and Hosta ‘Halcyon’ (© Peganum)

Anecdotes

• The “Toona” in cuisine: the young leaves of Toona sinensis are consumed in China and known as ‘xiangchun’. They are used to flavour dishes and are particularly prized in spring, often stir-fried with garlic or incorporated into omelettes, bringing a unique flavour reminiscent of onion.
• A symbol of longevity: in China, Toona sinensis is considered a symbol of longevity and prosperity. This may be due to its long lifespan and imposing stature, as well as its traditional uses in medicine.
• Quality wood for instruments: the wood of Toona sinensis is highly valued for making traditional Chinese musical instruments. Its fine texture and ability to produce good sound make it a material of choice for luthiers.
• Medicinal plant: in traditional Chinese medicine, Toona sinensis is used for its medicinal properties. It is believed to have beneficial effects on blood and the body’s internal balance.
• A tree for generations: some Toona sinensis are planted as birth trees in China, where a tree is planted at a child’s birth and grows with them. This symbolises the child’s growth and development.

In Asia, the young shoots are used in cooking