The 45 species recognised by botanists vary widely in the altitudes at which they grow and in the moisture content of their preferred soils. Dierama pauciflorum will even grow in standing water at the edge of ponds, says James, who adds that Dierama robustum is the most drought-tolerant. “It’ll cope well with extreme winter cold too, but only if it’s dry.” Some species will survive temperatures as low as -20°C, but only if the plants are in very well-drained soils.

The wet and cold winters typical of northwestern Europe can be fatal. James thinks that Dierama pulcherrimum is one of the most tolerant of such conditions. My experience with this plant and its hybrids is that it easily copes with -13˚C in wet, but not waterlogged, soil.

What are dieramas?

Dieramas are long-lived herbaceous perennials forming persistent clumps of semi-evergreen linear foliage. They originate from montane grassland from southern Africa to Ethiopia. Plants in cultivation are all from southern Africa.

Dierama flower in midsummer, with foliage growing between 30cm and 60cm. Flowering stems are much longer, bringing total heights to between 50cm and 2m.

They prefer mild winters and cool, moist summers. Most are hardy in maritime northwest Europe if placed carefully.

How to grow dierama

Where to grow dierama

Plant dieramas in full sun. They prefer soils that do not dry out, but that also drain well. Fertile soil is not necessary.

Shelter from cold winds and avoid frost hollows. This is vital. Westerly coastal winds are not a problem, though. Make sure the plants are not cramped by other perennials – they dislike too much competition and the flowers need space to be appreciated.

How to propagate dierama

Transplanting or dividing plants will result in a year’s dormancy before the plants re-emerge.

Collect seed when pods open in late summer or autumn. Sow the following spring in seed trays. When big enough to handle, transplant into 7cm pots and plant in final positions in autumn or the subsequent spring.

Dieramas hybridise easily and offspring will be unlikely to exactly replicate their parents.

What to plant with dierama

Agapanthus, crocosmias and kniphofias come from the same region. Medium-sized geraniums are a good contrast in form, and offer good colour harmonies; dieramas tend to sustain interest for a month or so later, too. Smaller grasses and Carex species combine well for a wilder look.

Problems with dierama

Dieramas are evergreen, but the leaves often look really tatty by winter’s end – they can be cut down to base level with no ill effects. Self-seeding can become a nuisance in some gardens, so be prepared to hoe off seedlings. Severe weather may seem to have killed the plant, but don’t dig it up – cut it back and allow offsets a chance to grow.

The best dieramas to grow

Dierama Wildside hybrids

Dieramas are promiscuous plants, and their seed rarely comes true. Keith Wiley, who grows many dieramas at his garden, Wildside, on the edge of Dartmoor, is realistic about how profusely the plants hybridise, offering his plants to gardeners in what botanists would call a ‘hybrid swarm’ of different shades.

Dierama pauciflorum

The most wet-tolerant species, in the wild this will grow on the edge of standing water, although it would be inadvisable to risk this in Britain. Reaches a height of up to 60cm.

Dierama pulcherrimum ‘Merlin’

© Jason Ingram

One of the finest dieramas, with dark flowers on gracefully arching stems. Bred by Cornish nurseryman Jim Cave, all of whose plants are named for Arthurian figures. 1m tall.

Dierama pallidum

© Jason Ingram

An obscure and rarely grown species with pale flowers above narrow, sword-like leaves. Typically reaches a height of between 80cm and 1m.

Dierama pulcherrimum

The most commonly grown species for good reason, as it is easy and with time forms spectacular clumps up to 1.5m tall, with flower stems spreading as widely.

Dierama robustum

A good name for a species whose flowering stems can reach to nearly 2m and which forms very large clumps with time. Flowers in various shades of pink.

Dierama dracomontanum

One of the smaller species (1m in flower, but often less) with flowers tending towards a brick red. From high altitudes, so relatively hardy.

Dierama ‘Guinevere’

With large white flowers on 1.5m stems, this was originally bred by the Cornish nurseryman Jim Cave. It is generally regarded as a good and easy plant.

Dierama reynoldsii 

An unusual wine-red with silvery white bracts shown off by pendulous, even floppy, stems. Flowers from June to August. It’s from high altitudes, so should be hardy. Up to 1.2m high.

Dierama pulcherrimum Slieve Donard hybrids

A range of colours, named after the Northern Irish nursery that bred many good dieramas in the 1920s and 30s. 90cm-180cm tall.

Dierama argyreum

© Jason Ingram

A smallish plant, with flower stems up to 1m tall, this has pendulous white flowers opening from pale yellow buds. In the wild it grows at lower altitudes, so may be less hardy.

Dierama mossii

A small species (50cm in flower) with pink flowers, this thrives in damp soil. It’s strong, slender stems flower in spring, well ahead of the larger dieramas.

Dierama ‘Cosmos’

© Jason Ingram

This is the darkest dierama yet seen, with the contrast between the petals and the silvery-white papery bracts particularly striking. Up to 1.2m tall in flower.

Dierama pulcherrimum ‘Blackbird’

The plant now widely sold under this name may differ from the original hybrid raised in the 1920s, but still, it’s undoubtedly a good and easy garden plant. Up to 1.2m tall in flower.

Dierama erectum 

More upright than most, with outward-facing flowers – useful characteristics, as is the fact that this is the latest to flower, sometimes into October. A relatively new introduction. 1.2m tall.

Dierama ‘Blackberry bells’

Nurseryman Ray Brown writes of this plant: ‘a smashing hybrid I made a few years ago… very vigorous and hardy, too, it seems, after this winter’. 90cm in height.

Where to buy dierama

Ballyrogan Nurseries, CountyDown. Tel 028 9181 0451 (evenings), email gary.dunlop@btinternet.com. Open by appointment only.

Plant World Seeds (seed only by mail order; plants available from nursery – address under Where to see, below). Tel 01803 872939, plant-world-seeds.com

West Country Nurseries, Donkey Meadow, Woolsery, Devon EX39 5QH. Tel 01237 431111, westcountry-nurseries.co.uk

Where to see dierama

Plant World Gardens and Nursery, St Marychurch Road, Newton Abbot, Devon TQ12 4SE. Open daily, 9.30am to 4.30pm, March until mid-October. plant-world-gardens.co.uk

Wildside, Green Lane, Buckland Monachorum, near Yelverton, Devon PL20 7NP. Check website for opening times. Tel 01822 855755, wileyatwildside.com

Logan Botanic Garden, Port Logan, Stranraer, Dumfries & Galloway DG9 9ND. Open March to November. Tel 01776 860231, rbge.org.uk/visit/logan-botanic-garden/