Roscoea: Planting, Growing and Caring

Botany

Roscoeas comprise 22 species of tuberous herbaceous perennials native to East Asia, mainly from China, Nepal and India. They grow in scree, meadows and forest edges, between 1,200 and 5,000 metres above sea level in mountainous regions, particularly the Himalayas. This explains their good hardiness, as Roscoeas can withstand temperatures as low as – 15 to – 20 °C.

Being deciduous, Roscoeas overwinter underground as tubercles and emerge late in spring, protecting them from the cold! In harsh climates, you can enhance this protection by applying a thick mulch over the stump for additional thermal insulation.

Roscoea belongs to the ginger family, the Zingiberaceae. Most plants in this family are tropical, but Roscoea comes from cool mountainous regions, proving rather hardy. This family includes many plants used as spices: turmeric, ginger, cardamom, galangal… as well as ornamental plants like hedychiums and alpinias.

Roscoea purpurea: Botanical illustration

The Roscoea was named by English botanist James Edward Smith in 1806 in honour of his friend William Roscoe, founder of the Liverpool botanical garden. Roscoe was known for his interest in Zingiberaceae and had a fine collection himself. The species name purpurea refers to the flower colour.

Roscoeas are not very large plants: they typically measure 30 to 40 cm tall. However, the smallest species, like Roscoea humeana, don’t exceed 20 cm in height, while the tallest, like Roscoea cautleyoides, reach about 60 cm. In the garden, Roscoeas are best placed at the front of borders.

Roscoea forms tuberous roots, resembling those of Dahlias. These allow the plant to store minerals and water, enabling it to overwinter dormant underground and thus protect itself from the cold.

Roscoea flowers in summer, between June and September depending on the variety. The flowers appear above the foliage at the top of their pseudostems (formed by the coiled leaf bases). Their flowers have a complex structure and strongly resemble orchid flowers. They measure about 5 cm across and have soft, luminous hues: most commonly mauve-purple or white, but can also be pale yellow (Roscoea cautleyoides) or bright red (Roscoea ‘Red Gurkha’). Their delicate, airy style makes them easy to incorporate into naturalistic partial shade gardens! The decorative parts of the flowers consist of three petals (with an upper petal forming a galea and two thinner petals) and four sterile stamens (staminodia), which resemble petals: two in the upper position and the other two fused into a central lower lip. The flower also has one fertile stamen bearing pollen.

Roscoea flowers come in beautiful hues depending on the variety! Roscoea purpurea, Roscoea ‘Red Gurkha’, Roscoea ‘Spice Island’ (photo Teresa Grau Ros), and Roscoea cautleyoides

The flower extends into a long floral tube containing nectar. When insects land on the flower to consume the nectar, they touch the fertile stamen which automatically deposits pollen on their backs. They then carry this to another flower’s pistil, enabling fertilisation and seed development.

Roscoeas are deciduous: their leaves die back in autumn and regrow in spring. They start late in spring: the first shoots and leaves only appear around June. This protects the plant from late frosts. It then grows rapidly to produce flowers as early as June or July.

Roscoea leaves are lanceolate, long and slender, arched. They typically measure between 15 and 25 cm long and are sheathing at the base (the lamina surrounds the stem). The foliar sheaths can be green or coloured: sometimes purple, brown or red depending on the species. The Roscoea ‘Spice Island’, for example, has brown foliar sheaths and dark leaves with reddish undersides, beautifully highlighting the flowers!

After flowering, Roscoea forms seed capsules. These have arils, small fleshy outgrowths eaten by insects, particularly ants. Attracted by the arils they consume, the ants carry the seeds with them, helping the plant spread.

Foliage of Roscoea purpurea ‘Red Gurkha’, Roscoea auriculata ‘Floriade’ (photos: Leonora Enking) and Roscoea ‘Cinnamon Stick’ with its reddish foliar sheaths

The main varieties of Roscoea

Most Popular Varieties

Our Favourite Varieties

Other Varieties to Discover

Roscoea purpurea

This is the type species, the most commonly cultivated, which has given rise to several varieties. From June to July, it bears violet flowers, 5 cm in diameter, which closely resemble orchid flowers.

• Flowering time August to October
• Height at maturity 40 cm

See the product sheet

Roscoea purpurea Cinnamon Stick

This Roscoea offers delicate, luminous flowers in late summer: pale mauve to rosy white, beautifully contrasted by dark, purplish-brown foliar sheaths.

• Flowering time September, October
• Height at maturity 50 cm

See the product sheet

Roscoea purpurea Spice Island

This variety forms cinnamon-brown foliar sheaths and dark green leaves with reddish undersides. In late summer, mauve orchid-like flowers appear at the stem tips, with a pink floral tube and upper petal creating a lovely gradient.

• Flowering time September, October
• Height at maturity 60 cm

See the product sheet

 

Roscoea cautleyoides

This species stands out for its yellow flowering, a rare hue among Roscoea! It’s particularly useful for brightening up a shady corner of the garden.

• Flowering time August to October
• Height at maturity 30 cm

See the product sheet

Roscoea purpurea Dalai Lama

Roscoea ‘Dalai Lama’ offers a beautiful purple-violet flowering in summer. It has been awarded the Award of Garden Merit by the Royal Horticultural Society (RHS).

• Flowering time August to October
• Height at maturity 40 cm

See the product sheet

Roscoea beesiana

Roscoea beesiana produces creamy white, almost yellow flowers, with irregular violet spotting on the lower petals.

• Flowering time August, September
• Height at maturity 40 cm

See the product sheet

 

Roscoea humeana

This is a small and early-flowering Roscoea, which bears intense violet, orchid-like flowers from May to July. It’s a collector’s plant, rarely cultivated.

• Flowering time June to August
• Height at maturity 25 cm

See the product sheet

Roscoea beesiana Alba

This variety stands out for its pure white, very luminous flowers.

• Flowering time July to September
• Height at maturity 40 cm

See the product sheet

 

Planting Roscoea

Where to plant?

Plant Roscoea preferably in partial shade, or in non-scorching sun if you live in the northern half of France. It needs shade during the hottest hours but still enjoys bright locations. Under dense, heavy shade, Roscoea may develop a more lax habit and less pronounced colours. If possible, choose a spot sheltered from cold winds.

Roscoea thrives in rich, humus-bearing soils: don’t hesitate to add well-rotted compost at planting time. It also prefers soils that remain cool in summer but are nevertheless well-drained. Regarding pH, Roscoea prefers acidic soils but will also grow in neutral soil. You can add some heather soil when planting.

As it enjoys well-drained, even stony soils and is naturally found in scree areas, Roscoea will thrive in a cool rockery in shade or partial shade. With its delicate orchid-like flowering, it’s also perfect for shaded naturalistic gardens and Asian-style gardens. It also adapts well to container planting and can enhance a terrace, small garden, or north- or east-facing balcony.

When to plant?

The best time to plant Roscoea is in spring, around May, once the risk of frost has passed.

How to plant?

In the ground:

1. Once you’ve chosen the location, dig a planting hole, at least 20-30 cm deep. Don’t hesitate to dig a wide hole to plant several young plants together.
2. Mix well-rotted compost and coarse sand into the planting soil to enrich the soil and ensure good drainage.
3. Plant the Roscoea tubercles 10 to 15 cm deep.
4. Cover with soil and firm gently.
5. Water thoroughly.

In pots:

1. Choose a pot at least 30 cm deep. Ensure it has drainage holes at the bottom to allow excess water to escape.
2. Add a drainage layer of clay pebbles or gravel.
3. Then add a mix of potting compost, garden soil, and coarse sand.
4. Plant the tubercles so they are buried under 10 to 15 cm of substrate.
5. Cover them with compost.
6. Water.
7. Place the pot in partial shade.

→ Learn more about growing Roscoea in pots in our advice sheet!

Roscoea purpurea

Maintenance

Native to monsoon regions, Roscoeas require moisture in summer and relatively dry conditions in winter. The ideal is to keep the soil cool in spring and summer: remember to water regularly when rainfall is insufficient. Once the Roscoea has flowered, you can reduce watering, then stop it completely as soon as the plant enters dormancy. Don’t hesitate to apply a layer of mulch at its base to preserve soil moisture for longer.

In most French regions, Roscoea can remain in the ground over winter, as it tolerates temperatures as low as –15 to –20°C. However, if you live in an area with particularly harsh winters (montane or semi-continental climate), you can protect the Roscoea from the cold by covering the stump in autumn with a thick mulch of dead leaves or bark. If grown in a pot, it’s easy to move it into an unheated greenhouse or any frost-free shelter. Similarly, planting the tubercles deep (about 15 cm underground) helps shield the Roscoea from frost.

Feel free to add well-rotted compost around the base of the Roscoea in spring to enrich the soil and encourage flowering.

You can remove faded flowers as you notice them, both for aesthetics and to encourage the plant to produce new blooms.

Watch out for snails and slugs in spring, as they enjoy nibbling on young leaves and shoots. You can protect your young plants with slug repellent or set up a slug trap. For more tips, check out our guide “Slugs: 7 Effective and Natural Ways to Control Them”. Otiorhynchus weevils may also target Roscoeas.

Propagation

Roscoeas can be propagated by sowing fresh seeds or by dividing clumps. Division is quicker and easier to succeed with than sowing.

Sowing

Sowing Roscoea is best done in late summer, in August or September, using fresh seeds (harvested shortly before).

1. Prepare pots with a fine, well-draining substrate, ideally a special sowing compost, then lightly firm and level the surface.
2. Sow the seeds by scattering them on the surface.
3. Cover them with a very thin layer of compost.
4. Water gently, using a fine spray.
5. Place the pots in a cold frame, in a bright spot without direct sunlight, and ensure the substrate remains slightly moist until germination.

Once the seedlings are large enough to handle, you can transplant them into individual pots. Patience is then required: Roscoeas grown from seed typically take 3 to 4 years before they start to flower.

Dividing Clumps

Division is the ideal technique if you have large, well-established Roscoea plants. It is best carried out in spring. You can divide your Roscoeas every 3 to 4 years.

1. Choose a large Roscoea clump, then carefully dig it up, making sure to dig wide enough to avoid damaging the roots.
2. Remove any excess soil if necessary, then divide the clump into several sections, ensuring each has roots attached.
3. Replant, either in the ground or in pots, burying the tubercles about 15 cm deep.
4. Water generously.

Association

With its generous foliage and original flowering, the Roscoea easily finds its place in an exotic-style garden. Pair it with colourful foliage in warm tones, such as Phormium ‘Pink Panther’, Colocasia ‘Black Magic’, Canna ‘Durban’, or Cordyline ‘Southern Splendour’. Opt for plants with striking, very large leaves: incorporate bananas, palms, Tetrapanax, Gunnera, Fatsia… Their lush vegetation will create a true jungle atmosphere! For flowering companions, consider crocosmias, kniphofias, Belamcanda chinensis, cannas… Alongside them, plant an Hedychium gardnerianum to enjoy its highly original flowering!

Exotic atmosphere with Colocasia ‘Black Magic’ (photo J. Rebel), Roscoea purpurea ‘Red Gurkha’ (photo Leonora Enking), Crocosmia ‘Lucifer’ (photo Vicky Brock), Cordyline australis ‘Southern Splendour’, and Hedychium gardnerianum (photo J.J. Harrison)

The orchid-like flowers of Roscoea are also perfect for naturalistic-style gardens. Their light and delicate style fits in beautifully! For companions, consider the airy blooms of willowherbs, masterworts, stem-clasping bistorts, astilbes, Veronicastrums, and Japanese anemones. You can also include garden orchids: discover, for example, the stunning Calanthe triplicata, which offers delicate little flowers with pure white petals!

Roscoeas can easily fit into a cool, shaded rockery, alongside saxifrages, dead-nettles, corydalises, and foamflowers. Also consider ferns such as the Asian species Coniogramme emeiensis, with its highly graphic fronds, and the Hart’s Tongue Fern, which forms clumps of beautiful, long, upright, evergreen green fronds.

Native to East Asia, Roscoeas will find their place in a Zen garden with an Asian style, alongside Japanese maples, Hakonechloa macra, hostas, and bamboos. This will create a very soothing atmosphere, perfect for meditation!

A naturalistic garden with Epilobium angustifolium, Roscoea cautleoides (photo Andy king50), Geranium riversleaianum ‘Mavis Simpson’, Persicaria amplexicaulis ‘Firetail’, Astrantia major ‘Ruby Star’, and Calanthe triplicata (photo Kuo-Chu Yueh)

→ Discover more pairing ideas with Roscoea in our advice guide!