When planting crocosmia, always plant the corms at least 10 cm below the soil level and with a space between corms of at least 15 cm. Find a location where the soil drains well, or work the soil with the addition of organic material (peat moss, compost, ground bark or decomposed manure all work well) to raise the level 5-8 cm to improve the drainage. Crocosmia will not survive in soils that are water logged. Place your crocosmia in a place where they will receive full sun.
After planting, water generously, soaking the soil. Roots and top growth will form within a few weeks. Once plants are established additional watering other than the rainfall is not required. A dressing of a good general fertilizer is recommended in early spring. When the plants have finished flowering, cut back the stems, but leave the leaves on even after they have died back. The leaves will gather sunlight and provide nourishment for next years flowering and will make good insulation against frost in the winter months. Water as needed. Leaves may be removed when they yellow.
You can propagate crocosmia by sowing seeds in containers in a cold frame just after they ripe or by dividing the corms. Division of plant clumps is best done in early spring, just before growth start and then replant the strongest corms immediately. Clumps should be divided every three years, in spring to maintain the vigor of the plant. In colder regions, the corms can be stored like gladioli, wintered in pots, or mulched heavily outdoors.