How to Plant, Grow, and Care For Crocosmia

Crocosmia brightens the border with sword leaves and blooms in bright orange, reds, and yellows. They emerge in summer among strappy leaves and flower through fall, providing nectar and pollen for bees, butterflies, hummingbirds, and other pollinators.

Eye-catching in both sun and dappled shade, the old-fashioned favorites delight with easy care. With consistent moisture, crocosmia happily naturalizes (sometimes too happily).

Crocosmia is vibrant in a group, offering contrast in texture and color. Here, we’ll explore how to grow these bulbous perennials for dynamic interest. 

What is Crocosmia?

The Crocosmia genus houses about seven species, with thousands of cultivars, many of which are Royal Horticultural Society Award of Garden Merit recipients for their bold blooms and ease of growth. Their fiery trumpets enliven the border with tubular flowers on gently arching scapes. The heirlooms also make striking cut flowers in fresh florals.

These low-growing perennials form clumps through spreading corms to create colonies. The spiked flowerheads appear in mid-summer for color through autumn. Related to gladiolas in the Iridaceae (iris) family, bloom spikes hold two rows of petaled trumpets in tapered sprays. The genus name derives from the Greek krokos, or “saffron,” and osme, “smell.” The flowers emit a subtle scent, intensified when dried petals, leaves, and stems steep in hot water.

Crocosmia, also called montbretia, copper tips, or falling stars, make lovely groupings in borders, cottage gardens, pollinator plantings, and cutting gardens, and naturalistic arrangements. Pair them with bananas, canna, flowering ginger, and agapanthus for a tropically-inspired display. Combine them with other perennials like salvia, dahlia, coneflower, rudbeckia, and ornamental grasses for a full-color panorama. Crocosmia also offers vertical interest in containers.

Characteristics

The South African natives hold their blooms for a long time in reds, golds, and bicolors. Bloom sprays open from the bottom to the top with a symmetrical flare. Slender, strappy foliage is medium green with a fan of blades. 

Upper growth stems from underground corms, thick, starchy, bulb-like roots that can be flat or round with fibrous layers. Some species spread vigorously in their optimal growing conditions, leading them to be invasive in some areas. Crocosmia x crocosmiifora is a popular ornamental that escapes garden cultivation. Most cultivars are better behaved.

Avoid planting the genus if aggressive in your region, which can displace other plants, including native species. Forming a dense mat, crocosmia is a competitor for water, sunlight, and nutrients. Thin and divide the colony to keep it from spreading out of bounds.

After flowering, bright green seedpods emerge, extending the interest and providing forage for birds. In their optimal conditions, they’ll drop, scatter, and yield seedlings.

With wildflower qualities, montbretia are carefree growers. Deer and rabbits mostly avoid them, and they have few pests and diseases. Hardy to USDA zone 6, they benefit from extra winter protection or lifting and storing corms in zones 5 and lower.

Native Area

Native to southern Africa, from Sudan to South Africa to Madasgar, Crocosmia is indigenous to provinces in southeastern Africa where they grow in moist grasslands and along streambanks.

Planting

Spring offers the best planting conditions with warming soils that foster quick sprouting. Start with corms or nursery potted specimens. For corms, plant them three to five inches deep with a close spacing to allow for a six-inch spread. Aim to have the slightly pointed end facing upward and the flat root end pointed down.

Plant potted nursery selections anytime from spring through fall, avoiding dry spells and heatwaves that can stress new plantings.

In cold climates at the lower hardiness zones, lift the bulbs for planting in the spring. The shallow-rooted specimens are easy to dig. Clean and dry the bulbs to store in a cool, dry spot over the winter. Plant them after the threat of spring’s final frost passes.

Transplanting

Spring and fall are the best times to plant the small bulbs. In containers, montbretia offers the “thriller” component with upright interest. Small varieties suit container culture well. For instant impact, start with nursery pots. Or, underplant spring-planted pots with the corms for a blooming surprise in the summer.

How to Grow

The unfussy perennials require little maintenance. Adaptable to varying conditions, the best blooming and vigor occur in consistent moisture and ample sunlight.

Light

In climates with cool summers, montbretia grows best in full sun with at least six hours daily. In hot, southern climates, they do best with afternoon protection from intense rays. Here, morning sun exposure and dappled afternoon shade are ideal for blooms that last on the stem. Flowering decreases in deep shade.

Water

Even moisture ensures overall health and vigor during warm months. Regular rainfall is usually sufficient, with additional irrigation during dry spells. No supplemental watering is necessary during winter dormancy.

Crocosmia tolerates periods of moisture and is relatively drought-tolerant once established. In very dry soils, growth will stunt and flowering lessens.

Soil

The flowering perennials grow across soil types, from organically rich to silty loams and sand. Good drainage and consistent moisture are prime conditions in the growing season. A neutral to slightly acidic soil pH is ideal, but most tolerate slight alkalinity.

Topdress with a layer of compost prior to planting for digging in as the corms or nursery-grown selections go in the ground. Especially for poor soils, compost improves soils to enrich nutrition, moisture retention, aeration, and drainage.

Temperature and Humidity

These cold-hardy perennials overwinter in USDA zones 6-10 (and in zone 5 with protection). In zone 5, site the bulbs in a sheltered location, like a south-facing wall out of winter winds, and mulch in the winter, or leave dormant leaves in place for insulation.

In summer, protect crocosmia from hot, dry winds to extend the summer blooms. Plants enter dormancy in winter to reemerge in spring’s warming conditions. They withstand temperatures down to 28°C (-2°C), depending on the variety.

Fertilizing

The durable growers do well with nutrient-rich soils without additional fertilizers. In containers, a slow-release granular or occasional liquid feed in early to mid-summer supports flowering.

Maintenance

In addition to their showy flowers, a beautiful attribute of crocosmia is its minimal maintenance requirements. Cut off spent flower stems at their base to promote new blooms. Deadheading redirects energy into growth and flowering rather than seed production.

Keep green leaves intact to continue to photosynthesize and collect energy for bulbs to store over the winter. After flowering, leaves often lay flat, and by fall, they’re ragged. Cut back or tidy up foliage after leaves turn brown and completely die back. Leaves turn yellow and brown as plants enter dormancy. In cold climates, leaving them in place offers added winter insulation.

To store corms, pluck them from the planting before low temperatures arrive in the fall. Shake off excess soil and allow them to dry out of direct sunlight. Store them in sand, vermiculite, or other dry media in a cool spot with temperatures between 35 and 45°F (2-7°C).

Propagation

Propagation is easy through division and offsets. Dividing benefits the group every few years by preventing overcrowding and rejuvenating flowering. It also helps reduce the spread into unwanted areas.

Crocosmia also propagate through seed, though it’s a slower-going process to develop fully flowering plants. It may take several years to reach flowering. If you have a cultivar, seeds may not be true to type (i.e., not a replica of the parent plant).

Division and Offsets

Each plant produces a new corm each growing season. Divide the clumps or separate the new corm offsets in early spring, just before new growth begins.

Dig the plant, capture entire corms, and wash away the soil. Separate them from the mother plant by pulling them apart or using a spade or serrated blade. Replant them in smaller groups in their new garden locations.

Growing From Seed

To grow montbretia from seed, collect fresh seeds in the fall as capsules brown and crack open. Sow them directly in a prepped garden area, covering them lightly with soil.

To grow seedlings in protected indoor conditions over the winter, sow them half-inch deep in seed-starting trays after collection. Water them in, and place the trays in bright, indirect light with temperatures between 60 to 70°F (16-21°C). Transplant seedlings after the final frost as soil and air temperatures warm.

Popular Varieties

With hundreds of cultivars, there are many color and size variations from which to choose. From soft orange and peach to deep scarlet, they fit a range of garden styles.

‘Lucifer’

Crocosmia ‘Lucifer’ boasts brilliant scarlet blooms on tall, two to four-foot stems. This popular cultivar is showy in the mid to back of the border with flowers from June to August.

‘Lucifer’ is one of the hardiest varieties with gracefully arching, wiry stems that hold the flaming trumpets. Tall stems may need staking to keep the scapes from toppling over, but most hold at two to three feet without additional support. ‘Lucifer’ has RHS’ Award of Garden Merit status.

‘Emily McKenzie’

C. ‘Emily McKenzie’ shines in coral shades with orange and gold highlights and a crimson halo. Its compact form holds two to three-foot stems and is a good fit for the border front as an accent or in pots.

With large flowers, the old-fashioned variety is a favorite in fresh arrangments. Blooms are up-facing on erect, multiflowered stems. ‘Emily McKenzie,’ too, is an Award of Garden Merit recipient.

‘Peach Melba’

From coppery buds to peachy orange petals, ‘Peach Melba’ brings unique tones to the starry bloomscapes. Yellow and gold centers add to a sweeping sunset glow amidst fresh green blades.

‘Peach Melba’ reaches 30 to 36 inches tall. Its full trumpets are a beacon to hummingbirds near and far. Like others in the genus, the late-season flowers add vibrant color at a time when other bloomers begin to fade.

Common Problems

Crocosmia is free of most pests and diseases. Other than managing aggressive growth and thinning the colony, the perennials require little oversight. One common garden pest that may cause damage and reduced flowering is spider mites.

Spider Mites

Spider mites are sap-sucking insects that live on the undersides of leaves. Their piercing mouthparts feed on cellular tissue. You may not see the tiny creatures without a magnifying glass, but their telltale webbing gives them away when their numbers are high.

Colonies of the insect live around leaf veins and underneath leaves. Females lay eggs, and the larvae quickly feed on sap and tissues. Pale spots appear on foliage. Adults feed and produce tight webs around leaves, stems, and branches.

In an infestation, foliage shows light yellowing and stippling on leaf surfaces and may become bronzey. Leaves become stiff and curl and may prematurely drop.

Spider mites occur in hot, dry, dusty conditions. They flock to plants experiencing drought stress. 

Treatment

Beneficial predatory insects like ladybugs, lacewings, and predatory mites help control populations. If you detect spider mites, spray the leaves with a strong stream of water early in the day to deter and knock insects off the stems. Spraying also rinses off dust.

Prune away affected parts. Dispose of debris rather than adding it to the compost pile, which can harbor and spread the insects.

A simple horticultural soap or oil, like neem mitigates severe cases. Plant-based insecticidal oils like garlic extract, clove, rosemary, mint, and cinnamon oils are effective organic controls. Be sure to follow label directions, as these treatments affect all insects, including pollinators. Time of day is essential in application, with before or after sunset being the best.

To prevent spider mites, water regularly to maintain evenly moist soils. Water fluctuations give spider mites a chance to increase, further weakening plants.

Frequently Asked Questions