Summer trips through the English and Welsh countryside are often enlivened by brilliant orange splashes of Monbretia along roadsides and ditches. In late spring these plants have gorgeous sheaves of soft lime-green dagger-like foliage that eventually get topped off with great bursts of bright orange flowers on thin wiry stems, which grow in huge great clumps. This is Crocosmia x crocosmifolia, which was introduced from France after the hybridisation of its South African parent plants.
The bad news is that it is listed as an invasive plant, under Schedule 9 of the Wildlife and Countryside Act 1981, and it is an offence to plant or otherwise allow this species to grow in the wild.
Luckily, most other varieties of Crocosmia rarely behave in such an invasive and uncontrolled manner. They are cheerful and garden-worthy with spires of funnel shaped flowers, which are carried above the leaves and good for cutting.
The modern varieties are bred from a range of species. A decent display can be had from July to September by choosing a selection from differing parentage and early and late summer flowering varieties.
These lovely plants need differing shapes of accompanying perennials to offset their stature. Some wonderful design groupings would include Bergenias and Rudbeckias, which will provide great contrast of leaf texture, flower form and long flowering season. Bulbs could include spring flowers such as Narcissi and bulbous ‘Iris’. Natural planting companions also include grasses. Calamagrostis x acutiflora 'Karl Foerster' and Anamanthele lessoniana, accompanied by small tussocks of evergreen Hebe topiarus look fantastic with these plants.
Crocosmias grow from bulbous corms and over time form large clumps that benefit from division. The divisions or offsets of the corms are best done in early spring, and replanted using good soil to back fill the plants. You will find that you will soon have enough to give away as presents!
Crocosmias are found naturalised in the moist but well-drained grasslands of the Cape region of South Africa. They also grow naturally along stream banks and forest margins. They can take pretty much any sort of soil apart from heavy and wet conditions, which cause them to rot. They do however thrive best in humus-enriched soils with an incorporation of sharp sand to aid drainage. Plant them in either full-sun or dappled part-shade.
They can take temperatures down to -10C° so will survive in most parts of the UK. They benefit from a layer of protection during the winter which could also include their own dead foliage.
Crocosmias will appreciate feeding regularly with a mulch of manure or compost and a slow release fertiliser. Remove all the dead foliage in early spring to allow the new growth to come through untroubled by a soggy wet mass on top of it.