Named after William Roscoe, one of the founders of Liverpool Botanic Gardens, Roscoea are members of the ginger family, Zingiberaceae that originate from Eastern Asia – specifically Southern China and the Himalayas.
Credit: Growing Tips
Roscoea are the hardiest of all the gingers and an ideal garden plant for the UK climate which has resulted accessibility of plants in nurseries and in the breeding of new hybrids. They have a tropical appearance and some liken them to orchids, although they are in no way related. Either way, their exotic aesthetic and uncommonness make these remarkable perennials a distinctive feature in any garden.
Species of Roscoea
There are about 20 different species of Roscoea, each with several forms. Individual cultivated plants can be incredibly variable and so the information and images given below should be used as guidance only. I have listed all 20 species (known to date) and a few notable cultivars and given information regarding some of the species.
Roscoea australis
With short stocky stems, Roscoea australis is not commonly cultivated and so is hard to find in nurseries. This is in part due to the national park status of its habitat, which is located in the Chin State of Western Burma, and the fact that it’s difficult to propagate by any other means than seed. R. australis requires a very free draining soil and so is best grown in containers. The mauve flowers are produced from May to July. (Picture Credit: Growing Tips.)
Roscoea x beesiana
A hybrid cross between R. cautleyoides and R. auriculata, Roscoea x beesiana is a tall specimen reaching at least 40cm high and sometime 60cm or more. Everything about it is slender, from the upright stems to the flowers, which are mainly yellow but often exhibit purple streaks. The flowering period is from July to August. (Picture Credit: Growing Tips.)
Roscoea cautleyoides
As one of the most cultivated and popular species, R. cautleyoides is easy to grow and makes an excellent garden plant. The narrow upright form, slender leaves and pale creamy yellow flowers bloom from May through to July which makes it the earliest to flower of all of the Roscoea species.
Roscoea ‘Kew Beauty’
Measuring about 50cm high, Roscoea ‘Kew Beauty’ is one of the finest cautleyoides cultivars. The flowers, which are large and pale yellow, sit atop upright stems and are produced from late spring. (Picture Credit: Growing Tips.)
Roscoea ganesgensis
Similar in some ways to R. purpurea and yet very distinctive in others, R. ganesgensis was first classified as an individual species in 1996. It’s about 15cm tall and produces broad, hairy leaves. Flowers are purple but labellum varies in darkness and indeed can be much darker than the example here. (Picture Credit: Growing Tips.)
Roscoea humeana
Another popular cultivated species, R. humeana is available in many forms of various sizes. The one pictured here is the purple form R. humeana f. humeana but yellow forms are also available, notably R. humeana f. lutea. Flowers are produced from June. (Picture Credit: Growing Tips.)
Roscoea purpurea
One of the most popular species to grow is R. purpurea due to it being tolerant of a range of garden situations from shady damp spots to dry south facing borders. When planted in a moist but well draining soil it will form upright clumps reaching up to 40cm high. Due to the range of habitats there are many forms of R. purpurea with several cultivars have being introduced. (Picture Credit: Growing Tips.)
Roscoea ‘Red Gurkha’
One such form is R. purpurea ‘Red Gurkha’. Unlike other forms which are purple or white, this unusual variety has red flowers and stems making it a much sought after perennial. Flowering later in the season than other Roscoea, ‘Red Gurkha’ produces scarlet coloured flowers whose labellum is distinctively larger that the dorsal petal. (Picture Credit: Growing Tips.)
Other Notable Species
Here is a list of notable Roscoea species that I have not mentioned above. I will endeavour to add detailed descriptions of these in time.
- R. alpina
- R. auriculata
- R. brandisii
- R. capitata
- R. debilis
- R. forrestii
- R. kunmingensis
- R. nepalensis
- R. praecox
- R. schneideriana
- R. scillifolia
- R. tibetica
- R. tumjensis
- R. wardii
How to Grow Roscoea
In The Garden
As you can see, there are several different species and each prefers slightly different situations but given the right conditions Roscoea will perform best when planted directly in the garden.
Credit: Growing Tips
Site and Soil for Roscoea
Where you plant Roscoea is key as they require their roots to be cool but their leaves to have access to at least some sunlight. The soil should be moisture retentive yet free draining, so add lots of organic matter if your soil is clay or sandy.
Raising the soil into beds is one method of improving drainage. A rock garden is ideal because not only is the soil well draining, the gravel, shingle and rocks used as a mulch provide a cooling shade for the roots. Similarly, a well mulched woodland border will do the same job provided the area has a least some dappled light.
With the exception of R. cautleyoides, most species don’t tolerate hot sunny conditions all day, especially R. alpina.
Planting Roscoea
Plant Roscoea rhizomes (bulbous roots) during the dormant season at least 10cm below the surface of the soil to protect them from frost. Although they appear hardy, the roots can be damaged by frost, killing the plant. With this in mind it is advisable to cover with a layer of mulch. Once planted ensure there are no air gaps around the roots – watering will help settle the soil.
Watering Roscoea
All species require a moist soil, especially throughout summer. R. alpina, R. capitata, R. forrestii, R. schneideriana, R. tumjensis and R. wardii will not tolerate drought so make sure you water during prolonged periods of dry weather. R. purpurea, R. humeana and R. auriculata will tolerate some dryness during summer but for best results try to keep the soil moist.
In a Greenhouse
Roscoea are not suited to excess soil moisture and although some species are more tolerant than others, winter wet is the leading cause of plant death. For this reason, growing under the protection of a greenhouse is a popular choice. All species can be grown in pots and by doing so you can control how much moisture your plants receive and eliminate the risk of water damage.
Credit: Growing Tips
However, this method is not entirely risk free. As mentioned, with the exception of R. cautleyoides most species don’t tolerate hot sunny situations and so precautions will need to be taken in order to provide tolerable conditions. By offering good ventilation and shading you can achieve a cool temperature inside a greenhouse. Even so, the temperatures in a greenhouse during the summer mean you will need to regularly water.
Propagating Roscoea
Sowing Roscoea Seeds
There are several places you can buy Roscoea seeds but keep in mind that the seeds should be sown as fresh as possible. Therefore, it is sometimes more reliable to collect seed yourself.
Seed can be collected in autumn but the location of seed pods varies between species. Some, such as R. cautleyoides and R. schneideriana, hold their seed pods above their leaves whereas others including R. tibetica and R. purpurea have seed pods within their leaves. These can be obtained by prising the leaves apart.
Sow seeds in pots filled with high quality seed compost. Water well and leave outside during winter, ensuring the pots do not dry out. Seeds will germinate the following spring but can take up to four years to flower depending on the species.
Some species, such as R. scillifolia, seed freely and you will often find them growing in your borders in random places. These can be transplanted to the desired area of the garden or potted up.
Credit: Growing Tips
Dividing Roscoea
Another way to propagate Roscoea is by division. This method is particularly important for pot grown specimens as pot bound plants can lose vigour. Division can be carried out during autumn as the leaves begin to die back. Carefully dig up the plants ensuring you do not break the roots and gently prise them apart. Pot them on or re-plant them in the desired location.
Roscoea Problems
Aside from summer drought and winter wet, there are few problems that Roscoea face. Pests rarely affect them especially if the plants are healthy. Slugs and snails can damage new growth and if grown in a greenhouse aphids and red spider mite can be problematic.
Further Reading
There are a few books which I have read and highly recommend if you would like to learn more about Roscoea. The first is The Genus Roscoea by Jill Cowley. It’s the most detailed resource about these plants and well worth buying if you love growing them. It features fantastic imagery and botanical art too.
The second is Hardy Gingers by T. M. E. Branney. Although only one section of this book is dedicated to Roscoea, it has highly detailed accounts of the species and many cultivars and forms. I would say it is essential if you plan on starting your own collection.
I have tried to make this plant profile as comprehensive and clear as possible, but if you are unsure of anything or have any questions please feel free to leave a comment below. As Roscoea are becoming increasingly popular I will be updating this post with new information and pictures in the future, so why not bookmark this page for future reference.
Growing Tips 