How to grow crocosmias

How to grow crocosmias

All you need to know about growing crocosmia, in this detailed Grow Guide.

A table displaying which months are best to sow, plant and harvest.
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Plant
Plant

Do not Plant in January

Do not Plant in February

Do not Plant in March

Do Plant in April

Do Plant in May

Do Plant in June

Do not Plant in July

Do not Plant in August

Do not Plant in September

Do not Plant in October

Do not Plant in November

Do not Plant in December

Flowers
Flowers

Plant does not flower in January

Plant does not flower in February

Plant does not flower in March

Plant does not flower in April

Plant does not flower in May

Plant does not flower in June

Plant does not flower in July

Plant does flower in August

Plant does flower in September

Plant does flower in October

Plant does not flower in November

Plant does not flower in December

Divide
Divide

Do not Divide in January

Do not Divide in February

Do Divide in March

Do Divide in April

Do Divide in May

Do not Divide in June

Do not Divide in July

Do not Divide in August

Do not Divide in September

Do not Divide in October

Do not Divide in November

Do not Divide in December

Crocosmias provide a burst of colour late in the season, when most other flowering plants have faded. There are hundreds of crocosmia varieties to choose from, flowering in red, orange or yellow from June to late summer, above ornamental, strappy, bright green leaves. They make an excellent cut flower.

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Crocosmias are also known as montbretia, although this tends to refer to the common species Crocosmia x crocosmiiflora. This has naturalised in many areas and is considered to be invasive. The cultivated varieties are less likely to become invasive.

How to grow crocosmia

Grow crocosmia in moist but well-drained soil in full sun to partial shade. Divide congested clumps every three to five years to rejuvenate them and encourage better flowering. In colder regions you may need to mulch the corms to protect them from frost.

More on growing crocosmia:

Find out all you need to know about growing crocosmia, below.


Where to grow crocosmias

How to grow crocosmia - crocosmia corms ready for planting
How to grow crocosmia – crocosmia corms ready for planting

Crocosmias are South African in origin, and require fertile, moist but well-drained soil. They thrive in full sun, but will tolerate light shade. In colder regions, choose a sheltered site.


How to plant crocosmias

How to grow crocosmia - planting crocosmia corms
How to grow crocosmia – planting crocosmia corms

Crocosmias grow from corms and can be planted like bulbs. Dig a generous hole, about 7-10cm deep and add a spadeful of well-rotted compost or other organic matter. Plant a handful of corms a few centimetres apart so you start out with a reasonable clump, and cover with soil.


Caring for crocosmias

How to grow crocosmia - <em>Crocosmia</em> 'Lucifer'
How to grow crocosmia – Crocosmia ‘Lucifer’

In dry summers you may need to water clumps, and mulch in autumn to protect the corms from frost. Crocosmia corms multiply readily, so clumps will become congested and flower less vigorously over time. The best time to divide and replant congested clumps is in spring.


How to propagate crocosmias

How to grow crocosmia - <em>Crocosmia</em> x <em>crocosmiiflora</em> 'Star of the East'
How to grow crocosmia – Crocosmia x crocosmiiflora ‘Star of the East’

Crocosmia corms multiply over the years, forming new corms which grow on top of each other in a ‘conjoined string’. To propagate crocosmia, lift clumps in spring and gently pull the corms apart. Plant up the top two corms from each string, which will be the newest and therefore make the most vigorous plants.


Growing crocosmias: problem-solving

Crocosmias can succumb to red spider mite, but are otherwise generally pest and disease-free. Some varieties can be too vigorous and may become invasive. Keep an eye on them and be vigilant – digging up and destroying the corms is the best way to deal with any invasive clumps. This may take several attempts.


Crocosmia varieties to grow

How to grow crocosmia - <em>Crocosmia</em> 'Citronella'
How to grow crocosmia – Crocosmia ‘Citronella’
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  • ‘Emily McKenzie’ – a compact crocosmia. The bright orange flowers have an attractive mahogany throat. Foliage is a slightly darker green and it can be slightly less hardy than other varieties
  • ‘Citronella’ – with upright, fresh green leaves and small, soft yellow luminous flowers
  • ‘Hellfire’ – bears tight clusters of enormous, bright crimson flowers from mid-summer to autumn
  • ‘Lucifer’ – with tall, arching sprays of intense, fiery red blooms. The first true red cultivar, ‘Lucifer’ is one of the tallest varieties growing up to 1.5m. The pleated leaves are also attractive in their own right and the seedheads can look decorative if left
  • ‘Harvest Sun’ – a relatively new hybrid, bearing large orange-red flowers in contrast with upright, fresh green foliage
  • ‘George Davison’ – at 60cm, this medium height crocosmia bears upright stems of golden yellow, freesia-like flowers from late-summer to autumn