How to Grow Crocosmia | Happy DIY Home

Tall and elegant, the crocosmia is a summer flower that brings both height and color to your garden. Similar in appearance to gladioli, the crocosmia is actually a member of the iris family.

Popular for their showy blooms that attract hummingbirds and pollinators to your flower beds, they also make great cut flowers. If you want to add these colorful blooms to your garden, our how to grow crocosmia guide will take you through everything that you need to know.

1 Distinctive funnel shaped flowers
The funnel shaped flowers provide a distinctive and colorful addition to the garden. 

Contents

What is Crocosmia?

Crocosmia (Crocosmia spp.), also known as coppertips or montbretia, is a perennial, flowering bulb. Originating in South Africa, the name crocosmia is derived from the Greek words for saffron and smell.

Easily identified by their sword-like foliage and funnel shaped blooms, bright red flowering varieties are the most common. You can also find yellow and orange flowering plants. Typically flowering in May or June, with a little care, coppertips can be encouraged to flower until the end of summer.

Thriving in full sun and partial shade positions, mature plants can reach anywhere between 2 and 4 ft in height. Once established these attractive flowers are a good way to bring color, height and soft structure to a flower bed.

Different Crocosmia Varieties

There are currently over 400 different varieties to choose from. All of these varieties have their own unique appearance or growth habit. Some produce plants with attractive rippled or pleated foliage while others have a quicker growth rate than others. These fast growing varieties are ideal for growers in cooler climates who don’t enjoy long, warm summers. Most varieties are hardy in USDA Zones 9 down to 5 or 6.

Some of the most popular varieties include:

  • Citronella, popular for its upright fresh green leaves and small yellow flowers.
  • Emily McKenzie is a compact variety that produces bright orange flowers with mahogany throats and dark green foliage. It is less hardy than other varieties.
  • Harvest Sun is a fairly new hybrid variety. Is grown for its large orange-red flowers with upright green foliage.
  • George Davison owes much of its popularity to its eye-catching, golden yellow freesia like flowers.
  • Bressingham Beacons is a warm weather loving variety which produces bi-color yellow and orange flowers. Despite some resilience, it is not always hardy in zones 5 and 6.
  • Hellfire produces tight clusters of bright crimson flowers from early spring until the fall
  • Lucifer is a tall variety which produces arching sprays of rich fiery red flowers. Its pleated foliage adds to the visual appeal.

2 Popular with pollinators
Popular with pollinators, take the time to find a variety that suits your growing space and preferences. 

When selecting your variety, make note of the plant’s spread and growth habit. You don’t want to select a variety that is too small or large for the space you want to fill. Crocosmia x crocosmiiflora varieties can have a vigorous, often invasive, growth habit. This means that it is not a good choice if you are creating a low maintenance garden.

Coppertips are grown from corms, these are closely related to bulbs. When selecting your corms try to select the healthiest ones possible. Check each bulb for any signs of mould or damage before purchasing them.

How to Plant Crocosmia

Crocosmia is a surprisingly easy to grow plant. As long as you get the planting position right they can be pretty much left to their own devices. Some gardeners dislike growing coppertips because the plants tend to spread and can become invasive. They are particularly vigorous in areas that enjoy mild winters and cool summers.

The best time to plant crocosmia is in the spring, as soon as the soil and air temperatures have warmed up. Plant corms in a full sun or partial shade position. Select your planting position carefully. While a little afternoon shade helps to keep plants cool in warm areas, too much shade can cause stems and foliage to become droopy.

Planting in a sheltered spot away from cold or drying winds helps to maintain a steady temperature around the plants. Coppertips can tolerate humidity and heat well, however the plants prefer milder temperatures.

The soil should be pH neutral and well draining. If your soil is too heavy or clay-like, it is better to plant crocosmia corms in pots or raised beds. Before planting work over the soil, digging in any necessary amendments.

For a good display plant corms in groups of at least 12. Plant each corm in a separate hole roughly 3 to 5 inches deep. Planting at this depth helps the flowers to develop a strong stem that can remain upright even when in flower. It also helps to protect the corms bulbs from winter frosts.

Before placing the corm in the hole add some well rotted compost or other organic matter. This gives the corms a nutritional boost, helping them to settle more quickly in their new position. Cover the corms with fresh soil. Space each corm 6 to 8 inches apart.

Install stakes, such as Bond Bamboo Stakes, to help keep the foliage upright. Without a little support the foliage tends to flop down to the ground.

Planting in Pots

Crocosmia can also grow in pots or raised beds.

Plant in containers filled with a balanced, general purpose potting soil. If you are planting in pots, make sure there are lots of drainage holes in the bottom of your chosen container. Plant the corms as described above. When planting in pots, you can plant the corms more closely together than when planting in the ground.

Water well. If you have planted in the spring within a few weeks grassy foliage should emerge. Don’t worry if foliage doesn’t appear immediately. It may just be a little chilly for the corms. Wait until the temperatures warm a little more and new foliage should soon emerge.

If the corms are too small, crocosmia plants may not flower in the first year. Allow the corms to remain in place. During the summer months they will grow and develop before flowering strongly in the second year.

How to Care for Crocosmia

Once established the crocosmia flower is a low maintenance plant. With just a little, basic care, the plants provide you with long lasting attractive foliage and colorful flowers throughout the spring and summer months.

When weeding around the plants, be careful not to damage or disturb the corms. There are a number of  weeding tools that you can use to keep your flower beds tidy and weed free.

3 Crocosmia provide long lasting interest
These attractive flowers provide long lasting color and interest to an outdoor space.

Water

After planting the corms, water to keep the soil evenly damp. Once the corms are established and new growth is visible you can reduce watering.

Water only when the top of the soil feels dry to the touch. If you are growing your coppertips in pots, try planting in self watering pots for a truly low maintenance garden.

Don’t overwater established plants. Crocosmia corms are prone to developing rot which is caused by sitting in wet soil for prolonged periods. If in doubt, allow the soil to dry out a little more before watering. I find that a soil moisture meter, like the Atree Soil pH Meter, helps me to know exactly how wet my soil is and when to water rot prone bulbs.

Fertilizer

There is no real need to fertilize crocosmia, they really are that low maintenance. Even in lean or poor soil the corms rarely require any extra fertilization. Too many nutrients, especially nitrogen, can cause excessive foliage production. This comes at the expense of flowering.

After flowering has finished for the year, some growers like to apply a dose of balanced, bulb specific organic fertilizer. This gives the corms a nutritional boost, encouraging them to return again next year. While fertilization isn’t necessary, this annual dose of nutrients can help to prolong the lifespan of the corms.

Pruning and Post Flower Care

Again, these are low maintenance flowers. There is no need to prune away healthy foliage. Once flowering has finished for the year, allow the foliage to remain in place. This enables the bulbs to store energy for the winter months.

When the bulbs are fully replenished, the foliage starts to yellow and die back. At this stage you can, if you want to, cut the spent foliage down to about an inch above ground level.

Self cleaning plants, spent flowers naturally fall away to reveal developing seed pods. These can either be cut away or left in place. In warm climates the plants happily reseed and spread. To prevent this, remove the seed pods as they form.

4 As flowers fade seeds develop
As flowers fade, seed pods develop. 

Cut Flowers

If you are growing your coppertips as part of a cut flower garden, harvest when the lower flowers start to open. To prolong flowering, put the cut stems in a vase or bucket filled with water in a dark place for 48 hours before incorporating into a floral display. The water should be around 100 ℉.

Overwintering Crocosmia Corms

Most varieties are hardy down to USDA zones 5. Here the bulbs can simply be left in place. If a particularly cold period is forecast, cover the corms with a protective layer of mulch or an Agribon Frost Blanket. Remember to remove the mulch or covers in the spring as the temperatures begin to warm.

In colder areas plants growing in pots should be moved to a sheltered location such as a greenhouse. Placing your pots on plant caddies enables you to easily move them around your home and garden. If you are growing in the ground, dig up the corms and store them in a dry, moderately warm position. Replant the corms the following spring.

How to Propagate Crocosmia

As corms mature they produce offsets. These are small corms that can be harvested and potted on to produce more crocosmia flowers. Sometimes the corms are pushed to the surface. In this case, simply pick them up and pot them on.

You may also need to dig down to the corms to divide them by hand. This should be done once every 2 to 3 years. Divisions can be made in the fall, as the plants start to die back for the year or in early spring. Dividing the corms helps to keep them healthy and growth vigorous.

To divide the corms, dig down to a depth of around 12 inches. Using a handheld fork or trowel takes a little longer than a spade but helps to ensure that you don’t accidentally damage the corms. Use your fork or trowel to lift the clump of corms from the soil. If the corms are covered in soil or difficult to see, gently rinse them underwater.

Typically a mature corm forms a chain which can be split into two or three clumps. Once the corms are fully visible, gently twist away the offsets from the larger corm. Dispose of any damaged or soft corms before planting as described above.

Growing from Seed

Allow spent flowers to go to seed. As the seed pods mature they develop a papery texture. They also turn brown in color. Keep a close eye on the top of the seed pods, as soon as they start to crack harvest the seeds. Don’t allow the pods to remain on the plant for too long. This risks the pods splitting and the plants self-seeding around the garden.

Open the seed pods to separate viable seeds from chaff. Ripe and mature seeds are dry and brittle. Harvested seeds can be stored in a cool, dry place until you are ready to use them.

Start seeds undercover in later winter. The day before sowing, carefully score the seeds. This helps roots to emerge. Soak them in warm water overnight to further soften the shells.

Start the seeds in trays or pots filled with fresh seed-starting soil. Sow the seeds about a quarter of an inch deep. Cover the seeds before misting or gently watering. Try not to disturb the seeds.

Place the seeds in a bright position, away from direct light. Germination is most successful if temperatures remain between 60 and 70 ℉. During this period, aim to keep the soil evenly moist. In ideal conditions germination occurs within 3 weeks.

Allow the seedlings to grow on until they have developed at least 4 sets of true leaves. When the temperatures are warm enough, harden off the seedlings before transplanting into a favorable position.

Common Pests and Problems

If planted in a favorable position, the crocosmia is generally disease and pest free.

5 Healthy foliage and flowers
Happy and healthy plants produce lots of healthy, green foliage and bright flowers.

Planting in poorly draining soil can cause corms to rot. A bacterial disease, bulb or rhizome rot can spread quickly in warm, humid weather. The first signs of rot typically include yellowing foliage and stunted growth. If rot is allowed to develop it can cause plants to fail. Watering correctly and amending the soil before planting helps to alleviate this.

Gladioli rust can cause foliage to develop black-brown or brown-yellow spores. Typically caused by planting in low light or overly humid positions a regular dose of sulfur powder or copper spray fungicide can help to prevent the issue.

Spider mites can target plants growing in consistently mild or dry conditions. Misting the foliage regularly helps to deter them.

Warning, do not ingest crocosmia. While crocosmia is not classified as toxic, these plants are members of the iris family which is considered toxic. Keep the corms out of the reach of pets. If your pet does consume a corm, consult your vet immediately.

6 Good in mixed flower beds
A good choice for mixed flower beds, these flowers work well in a range of planting schemes. 

A reliable member of the summer flower garden, crocosmia looks particularly effective in mixed flower beds. Good companion choices include:

A low maintenance bulb, crocosmia is a quick and easy way to introduce long lasting color and structure to the flower bed. A reliable plant that returns year after year, why not add some crocosmia corms to your garden today?

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