Where do Crocosmia come from and how does it effect their culture ?

Briefly, Crocosmia are a genus of Southern African bulbous plants which spread by producing what are called corms. All of the species grown in the UK come from 'summer rainfall areas' of South and
Southern Africa, and the varieties offered have been bred from these, and it is this that makes them suitable for growing outdoors as late summer and autumn flowering perennials in the UK. Most Crocosmia are quite drought tolerant however all benefit from being given plenty of water during their growing season.

There are chiefly four species that have been used in the horticultural development of this genus. These include Crocosmia aurea, Crocosmia pottsii, Crocosmia masoniorum and Crocosmia paniculata, the first two have smooth leaves and the latter two species can be easily recognised by their pleated leaves, and there have been many crosses between them. The main cross that many of you wil know is between  Crocosmia pottsii and Crocosmia aurea, as it was this cross that produced the Common Montbretia.

Crocosmia aurea, which can be quite a large flowered species is chiefly a woodland plant, and comes from more temperate and tropical areas, thus it is less hardy and in nature is given protection by the trees it grows under, the trees also providing shade and a more organic soil. Montbretia that have larger flowers than normal have more Crocosmia aurea blood in them and thus with a few exceptions they need to be treated differently that those with smaller flowers as they can be more tender and need different requirements. Indeed, some of the larger flowered Crocosmia definitely benefit from being given a little shade, Emily McKenzie especially.

Crocosmia pottsii is found in the open along streamsides in its natural habitat, and thus prefers moist conditions in full sun. However, that said it is very tolerant of a range of conditions. The true species is grown in the UK but there are many hybrid forms of it, and these are so vigorous that it is very difficult to get rid of them once you plant them, so really this small flowered species should only be grown if you have room for it, or you have a difficult spot in which to plant, as this plant is very much a survivor. However, there are some very good garden worthy forms of pottsii.

Both the species mentioned above are also supplied with ample nutrients in nature, C. aurea from the decomposition of vegetation in its habitat, and C. pottsii from the nutrients that it is supplied, found growing along streams.

The other two species, Crocosmia masoniorum and Crocosmia paniculata can be dealt with together as they originate from more mountainous areas of South Africa, and because of this they are more frost hardy than the other two species. Hybrids from these now represent quite a proportion of  what is being offered commercially, and I fully recommend their culture in colder districts. The most common of these offered is Crocosmia 'Lucifer' but there are also many other good varieties, and these differ in both height and flower colour. To generalise if you see  a listing of Crocosmia and you don't see ''x crocosmiiflora'' in the name then it is likely that what is offered is a hybrid between one of these species, eg. Crocosmia 'Walberton Yellow', which is a Crocosmia masoniorum hybrid.
Anything tall, such as 'Lucifer' or 'Zeal Giant' will have some Crocosmia paniculata in its blood.
Crocosmia paniculata was once known as Curtonus, and Antholyza, which gave it its common name 'Aunt Liza'.

We can conclude from this that smooth leaved Crocosmia (Montbretia) require warmer, more
organic, moist, nutrient rich soils; and that those with pleated leaves Crocosmia masoniorum and Crocosmia paniculata hybrids are less fussy and more tolerant of various conditions and locations. This is however a generalisation.