To avoid confusion with dwarf fescue blue turf grass, Festuca ovina glauca is more familiarly known as blue festuca. If planted close together and left to spread as a small scale ground cover, it is much lumpier and mounding than uniformly spreading turf. It is a clumping perennial that is more popularly grown as distinct tufts of finely textured blue gray foliage that looks like gray sea urchins.
Either individually, or in small herds, these resilient gray sea urchins mix nicely with brightly colored flowering annuals. They do not need too much water, but can tolerate as much as annuals want. Their color is best in full sun. Partially shaded plants are greener, with longer and more pliable leaves. So are feral plants that rarely grow from seed. Modern cultivars are bluer than classic types.
The evergreen foliage does not get much higher than half a foot, with thin and less impressive floral spikes that stand a bit higher in summer. It slowly spreads wider, but before it gets a foot wide, it will probably be going bald in the middle. Overgrown or balding plants can be dug and divided into new smaller plants in winter. Old foliage that gets shorn in the process is replaced in spring.
It was probably a good idea when it was introduced to California, but fountain grass, Pennisetum setaceum, became too much of a good thing for a few temperate regions in which it naturalizes and displaces native vegetation. Although it now works to inhibit erosion where it grows wild on the embankments of highway interchanges, it must sometime be mown because it is combustible.
In home gardens, fountain grass is more appealing if shorn back at the end of winter, and watered occasionally through the warmest part of summer. If feral seedlings need to be removed, a few may be left if they happen to grow where more plants are wanted, or to replace aging plants. Fountain grass should not be planted in regions where it is likely to naturalize but has not yet done so.
Fountain grass has narrow leaves that arch upward and outward so that the tips of outer leaves are just touching the ground. They might sag lower; or they might stand more upright. The fuzzy tan or pinkish tan flowers that bloom in summer may stand as tall as three feet. Individual plants live only a few years. The cultivar ‘Rubrum’ has striking purplish bronze foliage, and does not self sow.
Modern garden varieties of pampas grass found in nurseries are generally non-invasive. Their flowers are described as ‘sterile’, and therefore unable to produce seed. What that really means is that they are exclusively female, and unable to produce seed without male pollinators. However, they have the potential to be pollinated by naturalized pampas grass, and sow a few hybrid seed.
Of course, if naturalized pampas grass (Cortaderia jubata) are already in the area, a few tame dwarf pampas grass, Cortaderia selloana ‘Pumila’ will not make much of a difference anyway. They have the same elegantly cascading foliage and boldly fluffy flowers in the middle of summer, but on a smaller scale. The long and narrow leaves might stay less than five feet tall. The white flowers might stay below eight feet tall. Unfortunately, the leaves can easily cause nasty paper cuts!