Crocosmia: varieties, planting & care

With their alluring flowers, montbretias capture everyone’s attention. There are many varieties and colours to choose from, and they look lovely in garden beds and as cut flowers.

Although montbretias (Crocosmia) are easy to care for, there are a few things to bear in mind when overwintering them. In most regions, montbretias cannot be overwintered in the garden – they must be dug up and overwintered in a frost-free location. In this article you will learn about planting and caring for crocosmia as well as how to overwinter them. We will also showcase some of the most beautiful crocosmia varieties.

Crocosmia origin and characteristics

Crocosmias, also known as montbretias, belong to the iris family (Iridaceae). The genus consists of about 10 species, but mainly two hybrid forms are used as ornamental plants in gardens and parks. These are the C. masoniorum x C. paniculata and the Crocosmia x crocosmiiflora, a cross between the Valentine flower (Crocosmia aurea) and Potts’ montbretia (Crocosmia pottsii). These two parent species are native to southern Africa, where they can be found growing in sunny to semi-shady locations, such as in meadows and at the edges of woodlands as well as along riverbanks.

In colder climates, crocosmia are deciduous and only somewhat hardy. In subtropical climates, however, the plant is evergreen. They can also be grown in large containers, making it easy to bring them indoors for the winter.

Crocosmias are perennials that look very similar to gladioli (Gladiolus). They grow 50 – 120cm tall in dense, upright clumps. Montbretia spreads underground via rhizome runners and the crocosmia bulbs, which are actually corms, form daughter bulbotubers. The sessile, green leaves can grow up to 50cm long and fan out from the centre of the plant. The leaf shape resembles a sword, as is typical of the iris family. Up to 20 symmetrical hermaphrodite flowers are arranged in two rows on the arching inflorescence. They are funnel-shaped and, depending on the variety, can be red, orange or yellow. Crocosmias flower from July to September. Crocosmia are not particularly beneficial to our native bees and other insects.

Note: In subtropical climates as well as in the UK and Ireland, crocosmia is classified as an invasive species. Due to its affinity for spreading, there is a strong likelihood the biodiversity of affected ecosystems will be impacted.

The most beautiful crocosmia varieties

Montbretia varieties differ mainly in their flower colour, growth height, flowering time and winter hardiness. Here are some of the most beautiful crocosmias:

• Crocosmia ˈLuciferˈ: The fiery red flowers of this robust, vigorous variety appear from July to August. It grows 80 cm to 120 cm tall and is one of the hardiest varieties with a tolerance of about -15 °C. This variety has even won the RHS Award of Garden Merit, which is given to plants that are particularly well suited for growing in the British Isles.

• Crocosmia ˈSevern Sunriseˈ: This cultivar is also quite vigorous and robust. It grows up to 100 cm tall. Like ˈLuciferˈ it is relatively hardy and has orange-red flowers with a lighter centre.
• Crocosmia x crocosmiiflora ˈEmily McKenzieˈ: This cultivar bears large vivid orange flowers with a dark red ring in the centre from mid-August to September. It grows up to 75 cm tall and is hardy to about -5 °C.

• Crocosmia x crocosmiiflora ˈRed Kingˈ: ˈRed Kingˈ crocosmia is a robust, historical variety that bears small, orange-red flowers from July to September. It grows 40 to 80 cm tall and is hardy to -5 °C.
• Crocosmia x crocosmiiflora ˈGeorge Davisonˈ: The bright orange-yellow flowers of this cultivar shine from July to August. It grows about 60 cm tall and is hardy to about -5 °C.

• Crocosmia x crocosmiiflora ˈButtercupˈ: This cultivar grows up to 70 cm tall and bears apricot-yellow flowers from August to September. It is hardy to about -5 °C.
• Crocosmia x crocosmiiflora ˈLimpopoˈ: This variety bear flowers in orange and salmon pink, making them particularly striking. They can be admired from July until October. Montbretia ‘Limpopo’ grows to about 80 cm tall and is hardy to about -5 °C.

Planting crocosmia: location and procedure

There are a few things to bear in mind when choosing a location to plant montbretia. These are explained in detail below.

Where to plant crocosmia

Montbretia wants to be as warm as possible. This means that gardeners in cooler regions should choose a full sun to mostly sunny spot that is sheltered from the elements – in warmer regions, such as in wine-growing climates, a slightly shady location is more suitable. The same is true for crocosmias in pots. In cooler regions, it is a good idea to place the planter near a wall that still radiates warmth after sunset. Crocosmias like fresh, moderately nutritious and above all free-draining soil. Use a digging fork to loosen heavy, dense soils and then mix in about 30 % sand. You can find more tips on improving soil in our dedicated article.

The perfect location for montbretias:

• Full sun or mostly sunny and sheltered from the elements
• Soil that warms up quickly, free-draining; not compacted nor waterlogged
• Moist, slightly acidic, nutrient-rich soil

How to plant crocosmia

As crocosmia corms can be sensitive to frost depending on the variety, it is best to plant them a little deeper, i.e., 10 to 20 cm deep. Planting takes place in May once the frosts have passed. When preparing the soil before planting, mix in a little compost to give the plants optimal nutrients. When using planters, choose ones that are at least 30 cm tall and fill them with a high-quality potting soil. Our peat-free Plantura Organic Flower Compost is ideal for this, as it covers the plant’s initial nutrient requirements completely and has the necessary permeability thanks to the added crushed expanded clay as well as coconut and wood fibres. Add a 3 cm deep drainage layer of expanded clay to the bottom of the planter to allow excess water to drain away easily.

Organic Flower Compost, 40L

(5/5)

• Perfect for all flowering plants in garden beds & pots
• For beautiful blossoms & healthy plant growth
• Peat-free & organic soil: CO₂-saving composition

£16.99

Shop now!

Planting crocosmias in pots is also an easy way to prevent them from spreading. When planting montbretias in a garden bed, especially in warm areas, use root barriers or edging to stop them from spreading throughout the garden.

For a visually striking arrangement, try planting the crocosmia corms in small groups of 3 – 10 plants. In the bed, space the plants about 35cm apart. In pots, leave 5 – 10cm space between plants.

Growing montbretias from seeds takes more effort and time than growing them from corms. To top it all off, it is mainly the crocosmia corms that are available for purchase, making growing crocosmia from corms the sensible choice for most.

Crocosmia companion plants

In general, montbretias grow well beside various grasses (Poales) and other dark-leaved perennials with similar site requirements. Some great companion plants for crocosmia include red-hot pokers (Kniphofia), African lilies (Agapanthus spec.) and dahlias (Dahlia). Other happy neighbours are daylilies (Hemerocallis), red-leaved Heuchera varieties (Heuchera) and bee balm (Monarda).

Montbretia care

Except for overwintering, montbretias are easy to care for. Here are some things to keep an eye on.

Watering, fertilising and pruning crocosmia

Crocosmia prefer consistently fresh soil, so check the soil regularly especially on hot days and during dry periods and water when dried out preferably with rainwater. In summer, check potted crocosmia daily – the substrate should always feel slightly moist under the top layer. That said, avoid waterlogging, as this could quickly cause the corms to rot.

As for nutrient supply, a single application of mature compost in spring is sufficient. For crocosmias in pots, either change the potting compost annually or top up with some mature compost.

When to cut back crocosmias? Montbretias can be pruned back in autumn when the foliage has completely withered. Cut back above-ground parts of the plant to a few centimetres. This is particularly useful if the plant is to be overwintered indoors. During the summer vegetation phase, only cut off withered inflorescences or cut off fresh flowers to pop in a vase. When picking crocosmia for a vase, cut flower stems when only the first few flowers are opening. If the montbretias are grown in a weather-exposed location, fix them to support stakes to prevent the inflorescences from breaking.

Crocosmia not flowering?

If the plant does not flower, it could be due to the location. It is a common mistake to plant crocosmias in locations that are too shady and cool. The plants might also be suffering from waterlogging or drought. The solution to this problem is to transplant your montbretia to a suitable location, as explained above.

Are crocosmias hardy?

As mentioned above, montbretias are only winter hardy to an extent. Only about two varieties can withstand temperatures down to -15 °C – the rest are less tolerant of sub-zero temperatures. In regions with mild winters, the corms can be left in the ground. To improve their winter hardiness, we recommend planting the corms deeper and covering them with leaf mulch or wood chips. In colder locations, it is better to take the corms out of the ground and overwinter them in a frost-free location to avoid any losses. To overwinter your montbretias, dig up the corms before the first frost and place them in a bucket of slightly damp sand in a cool dark place. If you planted your montbretias in a container, simply move the container to a frost-free place.

Propagating crocosmia

As hybrid montbretias only develop sterile seeds, propagating them by seed is not possible. However, crocosmia usually reproduces itself with the help of daughter corms. These can be carefully separated from one another when they are dug up for overwintering and transplanted individually the following spring. In favourable locations, montbretias form many daughter corms.

Are crocosmias poisonous?

The ornamental plant is not edible and can result in mild poisoning symptoms. The above ground parts of crocosmia can cause mild gastrointestinal complaints in humans and animals. Ingestion of the corms may result in more severe reactions such as vomiting and diarrhoea.

Another unusual plant that also makes a beautiful cut flower is the protea (Protea). It, too, is not very cold tolerant and requires a little more attention when overwintering.