Regularly divide Crocosmia crocosmiflora​ and it will reward you with bands of dramatic colour in Autumn, says Carol Klein

Anyone who has visited the Cornish coast or the fuchsia-lined lanes of Southern Ireland in late summer or the first weeks of autumn will be familiar with the glowing orange splashes created by colonising montbretia. Crocosmia crocosmiflora, as it is properly known, was first introduced to the British Isles from France in 1880.

It was hybridised by M. Lemoine at his famous French nursery and was immediately recognised as a valuable plant. So it is, but the ease with which it establishes, coupled with the speed at which it travels, has made it ubiquitous. Familiarity breeds contempt and many gardeners regard it - rather unfairly - as a weed.

Since it burst on the scene there have been numerous other crocosmia introductions. Some have faded into obscurity but many have become firm favourites. Over the past few decades crocosmia have undergone a renaissance and are presently high on the "most fashionable plant" lists. Rightly so. They have a great deal going for them.

The main complaint about the plant from those who grow it is that its flowering diminishes year by year. Eventually the preponderance of green leaves far outweighs its vivid flowers. Action is then needed.

In the wild, or where it has naturalised, crocosmia moves into new ground so that the fresh rhizomes can feed themselves and break away from the older bulbous roots. In garden conditions, however, room for expansion may be limited or non-existent, so it may be penned in and starved. Chains of roots increase, sitting on top of one another in a congested mass until all the soil is eaten up. Clumps of starving rhizomes manage to produce a few leaves and little else.

When to lift

This is best done in autumn, but can be undertaken at any time during their dormant period providing the weather is mild. Never lift or replant crocosmia in frosty conditions.

Usually, by late October, foliage has turned brown. 

Crocosmia make chains of rhizomes like necklaces of fat beads. The older ones use up food and water and become a drain on the plant. The principle aim of dividing them is rejuvenation. By discarding the old rhizomes every two to three years and keeping the new, the plants will have vigour and produce bigger, better flowers.

Which varieties?

Flower colour is on the hot side of the spectrum, from scintillating oranges and reds to subtler warm yellows. Some are excitingly marked or flushed with red, in others the colouring is pure and solid. Heights vary between 18in and 4ft. Some flowers are dainty and rounded others are large showy stars.

Crocosmia 'Lucifer' is a very popular and reliable variety bred by Alan Bloom. Aptly named, its flowers are flaming red. It is the earliest to flower and its great pleated leaves (an inheritance from one of its parents, the bold Curtonus paniculatus) are an architectural feature in their own right. The seed heads provide further decoration. It is also extremely hardy.

Crocosmia 'Solfatare' is a glorious combination of amber flowers and bronze grassy foliage. It may need protection in colder areas.

Crocosmia 'Emily McKenzie' is one of the most flamboyant varieties. Her large deep-orange flowers are splashed with sealing-wax red both inside and out.

Crocosmia 'Citronella' has fresh green leaves and small, soft yellow luminous flowers. Easy to grow, hardy and upright.

Planting combinations

Try Crocosmia 'Citronella' with Imperata cylindrica 'Rubra' and Rudbeckia fulgida deamii. The undercurrent of the rich-crimson grass gives the pretty pale crocosmia flowers added innocence.

Crocosmia 'Star of the East' in front of Euphorbia characias or any of the glaucous spurges looks good. The blue-grey euphorbia leaves intensify the vivid orange of the crocosmia flowers.

Use Crocosmia 'Lucifer' with Dahlia 'Bishop of Llandaff' and the acid-green bracts of Euphorbia schillingii or E. palustris for undiluted zing.

Although crocosmia can be planted in clumps and patches it looks best in broad swathes, intermingling at the edges with other herbaceous plants of similar height. This kind of ribbon planting exploits its colonising tendencies and makes it flow.

When a large clump has been divided there is usually enough material to go to town. And, having been divided and refreshed it will have new vigour and voomph. Crocosmia should not be used timidly.

Although they will survive in shade they are never happy there and become unruly. Crocosmias are natives of southern Africa where they grow in damp open areas among grasses and perennial plants in full light. Good moist soil and an open sunny situation suit them best.

This article was originally published in 2003