The genus Crocosmia belongs to the Iris family (Iridaceae). Crocosmia are tall, summer-blooming plants that are just getting started when other spring bloomers like tulips are entering dormancy for the season.
Crocosmia grow from corms planted in the spring after the last chance of frost. Their red, yellow, or orange blooms are displayed on long, arching stems. The blooms open one at a time from the bottom of the stem. Their grass-like foliage adds billowy movement to the garden and is attractive all season.
This showy plant attracts hummingbirds and butterflies with its pigment-rich blooms and makes a gorgeous contribution to cut flower arrangements.
|Botanical Name||Crocosmia spp.|
|Common Name||Coppertips, montbretia|
|Plant Type||Perennial grown from corms|
|Mature Size||2-3 feet high|
|Sun Exposure||Full sun is preferred; partial sun is tolerated|
|Flower Color||Red, yellow, orange|
|Native Area||South Africa|
You don't have to pay much attention to Crocosmia corms after planting them. For the greatest effect, plant Crocosmia corms when the weather warms in spring and the danger of a spring frost has passed.
Plant the corms at least 3 inches deep and 6 to 8 inches apart both to help them survive the winter and to help plants maintain an upright habit. The long foliage and flower stalks can have a tendency to lay down, something you can control by installing grow-through plant supports.
Of the approximately 400 Crocosmia cultivars, a few cultivars are known to be invasive. The named cultivars are less likely to be invasive than the straight species. Crocosmia × crocosmiiflora (Montbretia) along with C. masoniorum (Crocosmia ‘Marcotijn’) and some forms of C. pottsii can spread readily.
Crocosmia grow and flower best in full sun. They will grow in partial sun conditions but won't flower as much as they do when planted in full sun. Some afternoon shade is fine in hot climates. If your partial shade Crocosmia plants are reaching towards the sun, dig up the corms once the foliage has faded and relocate them to a sunnier location.
Crocosmia plants don't need to be pampered when it comes to soil, but good drainage is important. If your soil is comprised of heavy clay, amend the soil with sand and peat moss to create a well-drained, loose consistency. The alternative is to grow Crocosmia plants in raised beds or containers.
Crocosmia plants need regular watering, but you should not overwater them. Water when the top of the soil feels dry.
Temperature and Humidity
Although Crocosmia tolerates high heat and humidity, it really takes off in drier climates with mild temperatures. Perhaps too much of a good thing isn't desirable, according to gardeners in places like the Pacific Northwest where plants have a tendency to take over the flowerbed.
Crocosmia grows well in lean or rocky soils and doesn't need supplemental fertilizer. Excessive nutrients can cause an overgrowth of foliage at the expense of the blooms.
Types of Crocosmia
- 'Lucifer' is a blood-red variety developed in 1966. It is the most popular crocosmia variety in the trade.
- 'Bressingham Beacon' has bi-color orange and yellow flowers but isn't reliably hardy in USDA hardiness zones 5 and 6.
- 'Citronella' has cheerful lemon-yellow blooms.
Cut down spent flower stalks, but don't remove Crocosmia foliage until it dies back naturally at the end of the growing season. While it is still green, the foliage photosynthesizes energy back into the corms to produce next years blooms.
You can propagate Crocosmia by removing the small offsets that form on the corms. This division process not only yields more flowers but also increases the overall vigor of the plants because they can become crowded as do their cousins in the iris family. Dig the corms in the spring just before new growth starts and separate the corms by hand. Replant them 6 to 8 inches apart.
How to Grow Crocosmia From Seed
Collect seeds from the seed capsules that form in the fall. Save seeds until spring, and then nick them and soak them in water to help speed germination. Plant seeds in the ground in sandy loam after all chances of frost have passed.
Potting and Repotting Crocosmia
Any commercial potting soil will do for your Crocosmia. Plant the corms closely in the container and watch for the grassy foliage to emerge a few weeks after planting. If no blooms occur the first season, your corms may be too small to flower, so leave them growing in place until the next season.
In their typical growing zones, crocosmia can be left in the ground for overwintering. A layer of mulch might help with peace of mind. In colder areas, dig up the corms and take them inside for storage in a cool, dry place during the winter months.
Common Pests and Plant Diseases
Crocosmia is generally disease-free except for cases where there is poor drainage that leads to root rot. However, spider mites can plague Crocosmia plants, especially when dry conditions prevail.
How to Get Crocosmia to Bloom
Keep in mind that Crocosmia might not bloom during their first year, because the corms are storing up energy preparing for future blooms. Several factors could be contributing to the lack of blooms If the plants haven't bloomed by their second season.
- Too much fertilizer can lead to lush foliage but very few blooms. Keep commercial fertilizers away from the plant and work in compost to help stabilize soil nutrients.
- Too much shade can lead to fewer blooms. To get the most from your plants, make sure they are planted in a location that receives six to eight hours of sunlight per day.
- Though the plant prefers well-drained soil, it also needs ample water, especially during times of drought. Watch the forecast and step in for mother nature with regular watering when rain is scarce.
What is the difference between Crocosmia and Gladiolus?
Crocosmia and Gladiolus plants have similar strappy foliage and bloom in the warm summer months. Although Gladiolus flowers come in a rainbow of flowers, they won't return as perennials the way crocosmia will. Because Crocosmia and Gladiolus enjoy the same sunny growing conditions, you can plant them as companions in the middle of the border or in containers.
Can Crocosmia grow indoors?
Container culture is a great option for gardens with compacted soil or just for getting some color around the deck and patio. You can plant corms more densely in containers than in the ground, about 6 to 8 inches apart. Plant the corms 3 inches deep in any potting mix, and water thoroughly. Foliage won't emerge until temperatures warm.
How long can Crocosmia live?
Depending upon the conditions, expect these plants to live between five and 20 years.