How to Grow and Care for Crocosmia

Crocosmia, commonly called coppertips or montbretia, is a cormous perennial grown for its arching spikes of funnel-shaped flowers in hot shades of red, orange, and yellow. Sword-shaped leaves rise from the corms in upright fans, and the flower stems can tower 2 to 4 feet above the foliage from midsummer into early fall. The plants are native to South Africa and naturalize readily in temperate gardens, spreading into larger clumps every year.

Crocosmia clumps keep a low-profile habit at ground level, with all the drama held up on the flower stems, which lets the plant fit into tight spots beside fences, paths, and foundations. It is also a dependable pollinator plant: hummingbirds and bees work the tubular flowers through the whole bloom season.

Crocosmia Care Basics

Crocosmia is a low-effort plant once the corms are in the ground. Give it full sun to light shade, soil that drains freely, and a warm, sheltered position, and it will multiply into a dense colony that blooms for six to eight weeks. It thrives in the same well-drained conditions as bearded iris and daylilies, so it slots easily into a low-water planting plan. Group the plants where they catch reflected warmth from a wall or pavement, which pushes bloom earlier in cool gardens.

Light and Soil

Full sun produces the heaviest bloom and the strongest stems, but crocosmia tolerates afternoon shade, especially in hot climates. The soil should be moist but well drained; heavy clay that stays wet rots the corms. Amend planting areas with grit or compost before planting.

Watering and Feeding

Water regularly during the first season while the corms establish. Established plants are drought tolerant and need water only during extended dry spells. Feed lightly in spring with a balanced fertilizer, and skip heavy nitrogen, which produces floppy leaves and fewer flowers.

Raising the Profile of a Border

Planted in drifts, crocosmia is a reliable way of raising the profile of a late-summer border when other perennials are fading. The vertical spikes add structure, and the hot colors pair well with ornamental grasses, rudbeckia, and late-blooming phlox.

Types of Crocosmia

Crocosmia species and hybrids span a wide range of heights, colors, and hardiness. Most garden crocosmias are hybrids of Crocosmia aurea and Crocosmia pottsii, bred for larger flowers and better cold tolerance. Hardiness varies by variety, from zone 5 with protection to zone 9. The common montbretia hybrids, grouped as Crocosmia x crocosmiiflora, are shorter and more cold sensitive than the larger-flowered cultivars.

Popular Varieties

Lucifer is the best-known hybrid, with intense red flowers, and it is one of the hardiest, surviving zone 5 with a deep mulch. Emily McKenzie shows deep orange blooms with a darker throat. Solfatare offers apricot-yellow flowers over bronze-tinted foliage, and George Davison produces bright yellow flowers on shorter stems. Named hybrids bred in the 1950s and 1960s, including Lucifer, still dominate catalogs because their color and vigor have not been beaten.

Planting Crocosmia Corms

Plant crocosmia corms in spring after the soil warms, or in early fall in mild climates. Before you buy, check the plant profile of each variety for mature height and hardiness, since the range runs from 18-inch dwarfs to 4-foot giants. Matching the plant to your zone and bed size prevents most disappointments. Corms left sitting on a shelf dry out, so plant them within a few weeks of purchase. Soaking corms for a few hours before planting is not required, but it speeds sprouting in dry spring soil.

Step-by-Step Planting

Corms go 3 to 4 inches deep with the pointed end up, spaced 6 to 8 inches apart. Plant in clusters of five or more for a natural drift rather than single stems scattered across the bed.

1. Loosen the soil to 8 inches and mix in compost or grit.
2. Set the corms 3 to 4 inches deep, pointed end up.
3. Space them 6 to 8 inches apart in clusters.
4. Water in well and keep the soil moist until shoots appear.
5. Mulch lightly to hold moisture and suppress weeds.

Container Planting

Crocosmia grows well in pots, which is useful in cold climates where the corms need indoor storage. Use a pot at least 12 inches deep with drainage holes, plant the corms at the same depth, and move the container to a sheltered spot for winter.

Growing Crocosmia in Pots and Borders

Whether in the ground or in containers, crocosmia rewards a simple routine: consistent moisture while growing, a spring feeding, and patience while the colony fills in. In borders, position the plants where the flower spikes can arch over the front of a bed. The cut stems last up to a week in water, so a small drift supplies plenty of material for vases.

Border Placement

Set crocosmia toward the back or middle of a border so the tall stems rise above lower perennials. In a mixed planting, the fiery spikes make crocosmia a high-profile plant that anchors the display from July to September.

Container Care

Potted crocosmia dries out faster than garden plants, so check containers every few days in summer. Refresh the top inch of potting mix each spring, and divide potted corms every two to three years when they crowd the pot.

Overwintering and Dividing

Cold-climate gardeners treat crocosmia one of two ways: mulch it in place and hope for the best, or lift the corms and store them indoors. In zone 6 and colder, a deep winter mulch of 4 to 6 inches of leaves or straw protects corms left in the ground. In zone 7 and warmer, crocosmia usually survives without any protection at all.

Lifting and Storing Corms

After the first hard frost blackens the foliage, lift the corms, cut the stems back, and dry them for a few days. Store them in a cool, dry place at about 40 to 50 degrees F in a box of peat or sawdust, then replant in spring.

Drying Before Storage

Spread the corms on a tray or screen in a dry, airy spot for three to five days before packing them away. Label the container by variety and color, since dried corms of different types look nearly identical by spring.

Dividing Clumps

Established colonies form chains of new corms above the old ones and need division every three to four years. Divide in spring as growth begins, replant the freshest outer corms, and discard the shriveled old ones. Skipping this chore is one of the most common pitfalls when growing crocosmia, since crowded colonies bloom less and bloom later. Mice sometimes eat stored corms, so keep them in a metal can or a mesh bag rather than an open box.

Pests, Diseases, and Bloom Troubleshooting

Crocosmia has few pests, but gladiolus thrips, spider mites, and slugs can damage the foliage, and rust or corm rot appears in wet, poorly drained conditions. Most problems trace back to the site, and fixing the site fixes the plant.

Common Pests and Diseases

• Gladiolus thrips: silvery streaks on leaves and flowers; remove infested growth and avoid replanting in the same spot.
• Spider mites: fine webbing and stippled leaves in hot, dry weather; hose the plants off and keep the soil moist.
• Slugs: ragged holes in young leaves; hand-pick at dusk or use grit barriers.
• Corm rot and rust: yellowed, spotted foliage and soft corms; improve drainage and remove infected plants.

Why Crocosmia Fails to Bloom

A healthy plant that produces only leaves is almost always in too much shade, too crowded, or too cold. Heavy nitrogen pushes leaves at the expense of flowers, so feed lightly. Move crowded clumps to full sun, divide them, and replant at proper spacing so the colony keeps a precise profile in the border; bloom returns the next summer. Plants that flower poorly after a mild winter may simply be young, since most corms bloom reliably in their second year.