Crocosmia likes fertile and well-drained soil which is full of organic matter. Compost enriched Sandy loam or soil is best. It does not like the heavy clay soils, which are prone to retaining much water and case a bulb rot. The PH levels of slightly acidic to neutral are optimal. Another benefit of adding a layer of mulch is that it keeps the soil moist as well as containing the weeds. Preparation of the soil is important because of high growth of the roots and healthier blooming. Light spring fertilizing with a balanced fertilizer stimulates rich foliage and colored flower spikes.