Growing Crocosmia

Crocosmia is easy to grow and flowers from mid to late summer in strong shades of red, orange and yellow. It is reliable, a great border plant with lovely bold flowers in strong colours. Crocosmia is herbaceous, which means it dies back over the winter to bare earth, regrowing each spring. Crocosmia forms clumps with attractive, sword-shaped leaves and flowers for a long time.

Crocosmia originates from South Africa and has flowers in all the sunrise colours with much variation in height; varieties such as Jackanapes, and Canary Bird can be as small as 60cms (24") compared with Lucifer and Columbus which grow to 120 cms (48".) Height can be an important factor where to place plants in the border.

Crocosmia is easy to grow, possibly too easy as some varieties are vigorous, if not invasive. To check growth, pull up and remove any unwanted spread, the plants corm (root) lies close to the surface, making it easy to remove. After a few years and the Crocosmia plant has become established, it may be necessary to dig out around the plant to thin it each year to stop it taking over. In the autumn I dig out, or pull out by hand, around the edge of the patch of the Crocosmia to make an obvious demarkation line between it and the surrounding plants and also so it does now swamp them.

Crocosmia Lucifer, illustrated in the left and right images, looks magnificent, and is a tall architectural plant, and as a taller variety, it requires support. In terms of maintenance, most Crocosmia flop over, which can smother plants next to them, and for which reason they are best supported, even the shorter varieties.

 Also, some specialist varieties, often seen at plant fairs and shows, are attractive, but unfortunately they may not be fully hardy. (explanation of frost hardy)

Crocosmia also makes great cut flowers and as the clumps produce so many blooms there is plenty for the garden and the vase. 

How to Plant Crocosmia

Crocosmia will tolerate a wide range of conditions with a strong preference for a spot which is not too dry with plenty of sun. If the site is too dry, flowering will be reduced. The cheapest way to grow Crocosmia is from corms, rather than plants, and they will grow easily from corms and flower reliably.

Crocosmia corms are similar to bulbs and the best time to plant is early spring, so they hydrate in late winter/early spring rain. Once hydrated, Crocosmia will grow as soon as the soil warms up in early spring. Plant Crocosmia corms about  8-10 cms (3-4") deep below soil level in a group to form a clump.  Crocosmia is pest free and provides excellent colour to the borders.  Crocosmia were formerly known as Montbretia and may occasionally still be referred to by this name.

You do not need to prune Crocosmia, as a herbaceous perennial,and in late autumn the top growth will disintegrate, and dieback, leaving bare earth until spring, when fresh shoots will appear.

How to Stake Crocosmia

Crocosmia, if left unchecked, flops over, and lies over adjacent plants. It is not a good neighbour and to make it behave, it needs to be staked to make it grow more upright and contain it.  In the image I have used Cornus stems (cut off in the late winter,) to make a loop. You could use stakes and string. The taller varieties will need longer stakes and at least two rows of string.

How to stake Crocosmia

Crocosmia is a green wheelbarrow plant, being easy to grow and low maintenance

Planting combinations for Crocosmia

Crocosmia with grasses
Crocosmia with Grasses

Crocosmia mixes well with grasses and, if possible, it's best to mix taller grasses with taller Crocosmia. For a bright combination, Crocosmia also looks good with blue Agapanthus, a tall combination for the back of a border. If you are growing Agapanthus in containers, you can place the container in the border next to the Crocosmia for the same effect. 

Crocosmia lucifer and Agapanthus
Crocosmia with Agapanthus

Good varieties of Crocosmia to grow

Many Crocosmia listed here are fully hardy, which means you can plant and leave them in the borders over winter. C.Lucifer is illustrated above left and right, C. masoniorum  'Rowallane Yellow' is as the name suggests, a lovely yellow variety up to 80cms; both are good varieties which also have the RHS award of garden merit.  

C.Lucifer a very tall, striking variety growing up to 8m ( above right) and was developed in the 1960s by Alan Bloom of Bressingham Plants who was so prominent in the plant world and his family continues the tradition.  He developed  C. `Bressingham Blaze', a fine red, and C.`Spitfire', an orange-red, the shorter  C.`Vulcan' a bright red and C.`Emberglow' a paler orange.  

All Crocosmia bloom in shades of red, yellow, orange and some blend the two, such as 'Jackanapes'. Most Crocosmia are fully hardy but not all, such as Jackanapes so it is worth checking first, especially if your garden is more exposed.  Crocosmia prefers to be planted in a sunny spot, but are tolerant of a range of conditions including heavier, wetter soils. They may flower less well in less ideal conditions.

Crocosmia is only one of many beautiful summer flowering plants and also ideas on summer planting combinations.

C. 'Severn Sunrise'

Crocosmia severn sunrise

In 2017 C. 'Severn Sunrise'  was awarded the RHS Award of Garden Merit. It has flowers which are a lovely soft orange, tinged with peach growing up to between .5 -1m (20-40"). It is hardy to around -15 H5 and in the colder parts of the country it will benefit from a winter mulch.

C. 'Carmine Brilliant'

Crocosmia Carmine Brilliant 2

This is Crocosmia 'Carmine Brilliant' a lovely soft pink and yellow variety growing up to around 60cms. A good all rounder, not fussy about soil type, growing in sun or partial shade, sheltered or exposed spot with the RHS award of garden merit.

C. Jackanapes

Crocosmia-Jacknapes

Another Crocosmia which is very easy to grow and tolerant of most conditions. It is an attractive bicoloured variety growing up to between .5 and 1 meter. It is quite hardy but not fully, only H5 requiring a sheltered spot or mulch in exposed areas.

C. Norwich Canary

Crocosmia Norwich Canary (2) 310

A bright yellow variety not often found for sale, but a variety bred from it C 'George Davison' is  much more common and is very similar, also yellow, a shorter variety growing up to 40cms.

Last updated 08.12.2021