Fescue (Festuca spp.) is a diverse group of over 100 grasses growing in temperate climates throughout North America, Europe and North Africa. Included in the fescues is the cool-season grass, tall fescue, popular in North America as a lawn grass. Also known to many gardeners is blue fescue (Festuca glauca), an ornamental grass with blue-green foliage and a dense, mounding habit. Key to growing blue fescue is providing and maintaining good soil.
Blue fescue is a mounding grass growing 6 to 12 inches tall. It is topped by discreet plumes of light green flowers in summer. Blue fescue is herbaceous (dying back in winter) in its northern limits and semievergreen in its southern limits. It is often used as a ground cover or as a specimen in the rock garden. Elijah Blue is a variety appreciated for its dense form and intense blue-green blades.
Blue fescue grows in U.S. Department of Agriculture (USDA) zones 4 through 8. It prefers full sun and moderately moist, well-drained soil. The nutritional requirements of blue fescue are relatively low. When the previous year's blades are cut back in early spring, it grows a fresh, porcupine-like tuft of new foliage. Blue fescue is generally regarded as deer resistant.
Achieving the perfect soil for blue fescue is not difficult. While it can tolerate dry to moderately moist soil, it must have well-drained soil. Sandy loams, with moderate amounts of organic matter for nutrition and water-retention, are ideal. Rock gardens, with their perfect drainage, are popular spots for blue fescue.
Amend heavy, clay soils with a lot of coarse sand--half or more. Pea gravel is an acceptable substitute for sand. Add up to 1/4 compost to sandy and gravelly soils to improve water and nutrient retention.
Plant blue fescue with plants also liking well-drained soil. Herbal perennials like lavender, rosemary and thyme can share soil with blue fescue. Plant blue fescue with alpine plants like edelweiss, Dianthus and sea pinks. When companion planting, the quality of soil structure can be more easily controlled.
Maintain blue fescue soils by using organic mulch and organic matter sparingly, which increase water retention. Using pea gravel as a mulch helps prevent soil from splashing onto blades during rain, reducing fungal problems and crown rot. It also does not break down, thereby increasing water retention.