Crocosmia Culture

Growing Requirements

• Crocosmia grows in nearly any soil of average fertility, but performs best in slightly acidic soil. The corms tolerate both drought and dampness, but well-drained soil is critical because the plants don't tolerate soggy soil or standing water. Amending the soil with 2 to 4 inches of compost or chopped bark improves drainage and helps maintain a lower soil pH. Full sun is best in most climates, but crocosmia benefits from afternoon shade in hot climates.

Planting

• Plant crocosmia corms after all danger of frost has passed in spring. Planting depth depends on the climate. In the cooler climates of USDA zones 3 through 6, plant them 6 inches deep. In warmer climates, plant the corms about 3 inches deep. Allow 6 to 8 inches between each corm. Add 2 teaspoons of bone meal or all-purpose granular fertilizer in each planting hole to get the plants off to a good start. For a dramatic effect, plant corms in groups of 12 or more corms.

Care

• Although crocosmia is a drought-tolerant plant, it benefits from regular water during warm weather. Water only when the soil is dry, providing enough water to soak the soil around the corms to a depth of about 6 inches. While crocosmia is resistant to most pests, it is occasionally bothered by spider mites. Spray the plant thoroughly with a ready-to-use insecticidal spray, covering all the leaf surfaces, to help control spider mites. Divide crocosmia when the plant becomes crowded or loses vigor -- usually every two to three years.

Winter Maintenance

• Crocosmia requires no winter protection where winter temperatures remain above 10 degrees Fahrenheit. The hardy bulbs survive cold winters with temperatures as low as minus 5 F as long as the ground is covered with a heavy layer of mulch, such as straw, bark chips or pine needles. In colder climates, either grow crocosmia as an annual or dig up the corms and store them for the winter. If you choose to store the bulbs, dig them soon after the foliage is killed by frost.