Plant of the Season – Summer

Roscoea purpurea ‘Red Gurkha’ AGM

I am delighted to recommend this late summer–flowering roscoea which has become more widely available in the trade in recent years. The plant was introduced into cultivation in September 1993 from material collected by Baker, Burkitt, Miller and Shrestha in the Buri Gandaki valley, Nepal. It was initially named R. purpurea forma rubra and then given the cultivar name ‘Red Gurkha’. Over the past few years this cultivar has been crossed with another form of R. purpurea ‘Brown Peacock’ by Robin White and some fine seedlings have arisen. One has been selected and given the name R. ‘Royal Purple’.

The recommended cultivar is easy to grow in an open, sunny position with the provision of a deep, well drained soil. I have recently noted the real benefit of adding a generous portion of washed river sand with a few handfuls of well-rotted horse manure when planting roscoea. The only time I am nervous of losing these subjects, including arisaema species, is when they have failed to establish prior to the winter. I also mulch these plants, when dormant, with a 5cm layer of well-rotted bark as a form of winter protection. The form of ‘Red Gurkha’ that I grow (with red pseudo-stems) has never set seed and I must admit I have made no attempt to hand-pollinate. I gather that there are forms which have green pseudo-stems and that these are more likely to set seed. Readers can make their own choice!

Propagation is quite simple from division of established clumps and there are a number of times to carry out this practice. My preference is to lift clumps in late autumn as they commence dormancy but great care must be taken not to damage the congested, fleshy roots. The easiest way to identify the individual plants and the resting buds is to completely wash the roots and then prize them apart. Each division can then be potted up in a deep pot consisting of a very well drained mixture containing plenty of sand and perlite. Having watered the plants it is important to keep them frost-free and never to allow them to become water-logged. I prefer to plant out in the spring after fear of frosts. Plant deeply with plenty of washed sand as mentioned previously, at least 20cm apart.

Plants are becoming more widely available and this is my recommended nursery:

Desirable Plants, Totnes, Devon,