Crocosmia Planting Guide

Crocosmia are South African relative of the familiar gladiolus. You can see it in the foliage. Same narrow, sword shape. Leaves that originate near the base rather than along the stem. Crocosmia were brought to Europe in the mid-1800s and became increasingly popular over time. By the 1920s, hundreds of crocosmia cultivars had been created and flowering clumps could be found in most flower gardens.

Everything changed with the onset of World War II. During that period, gardeners were encouraged to “Dig for Victory” and to replace ornamental gardens with vegetable plots to support the war effort. Crocosmia, or montbretia as this plant is called in Europe, was uprooted and tossed in the compost heap. With time, crocosmias have made a comeback and are increasingly included in mixed perennial borders. Hip, hip, hurrah!

Choosing a Site

Crocosmia prefer full sun sites in most of the country, but do appreciate a bit of afternoon shade in the hottest regions. These plants thrive in moderately fertile, well-drained soil. Where happy, they may naturalize and spread. Crocosmia are good choices for breezy sites because their foliage bends with the winds rather than breaking.

Soil Prep

Average to rich soil with medium amounts of moisture will support healthy crocosmia. These plants do not thrive in hot, dry environments. Adding a slow release fertilizer when you plant can be helpful if your soil is a bit lean.

When to Plant

Plant crocosmia corms outdoors when frost danger has past and the soil has warmed. Once established, crocosmia can manage moderately cold weather.

How to Plant Crocosmia Corms

The corms of crocosmia look a bit like large crocus bulbs, with pointed tops and bottoms that are often slightly indented. The bottoms also can be identified because there’s sometimes a dark circle there. Plant with the points facing upwards and cover with 3-4” of soil. Water well to settle the soil around the corms. A light mulch that helps hold soil moisture, but does not lean against the stems (can promote stem rot) is often helpful.

Crocosmia corms can take 3-5+ weeks to begin to sprout depending on soil temperature and moisture levels. Typically, the corms vary in sprout timing so don't worry if a few show up and the others take their time. Patiences is helpful the first season.

During the Season

Crocosmia plants take a few seasons to fill out into nice big clumps. Give the bulbs water every few days as they settle in, assuming Mother Nature doesn't take care of that for you, and expect to see slender blade-like sprouts in a few weeks.

Crocosmia require about an inch of moisture total weekly and beside that, need little care during the growing season. You can trim off spent flowers to keep the plants looking their best. Feel free to cut flowers and buds for arrangements.

At Season’s End

Late in the fall, or in the spring before new growth appears, trim your crocosmia foliage to an inch or two above soil level. This will allow the fresh leaves to grow unencumbered and will keep your garden looking neat.

Dividing Older Plants

When crocosmia clumps grow large they may be divided for rejuvenation and for additional plants. Dig, split with a shovel and replant in spring just as the new season’s sprouts are beginning to appear. Water daily for a week while the plants resettle. Flowering may be reduced that first season as the plants reestablish.

Insider Tips

  1. Hummingbirds love crocosmia flowers.
  2. The buds of crocosmia are unusual; colorfully banded. Snip some for snazzy additions to bouquets. Flowering stems are best cut when the lowest blooms have just begun to open.
  3. Crocosmia can be slow to settle in and typically become fuller clumps in the second and third summers. If your plants are a bit on the thin side their first summer, don’t worry. They’ll fill out in subsequent seasons as the roots produce additional corms and those produce sprouts to thicken the clump.
  4. Feel free to trim off any brown leaf tips that might develop late in the season. This is an esthetic option, completely up to you.
  5. Crocosmia bloom for about two months, from early June into August. All varieties are in bloom by July 4th which has earned them the common name “firecracker flowers”.
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Success Snapshot

Light: Full sun to 3/4 day sun

Soil: Average

Depth: Cover with 3-4" of soil

Water: Average moisture

Uses: Beds, mixed borders and edges

Tip: Excellent cut flowers; other worldly buds

GUIDE: Crocosmia Planting Guide

They Start Out Looking Like This: