Purple moor grass (Molinia caerulea) is a great little ground cover grass or ornamental grass for wet and acidic soils where few other grasses will survive – never mind thrive. It is however fairly slow to establish itself and spread. So don’t look for this grass to take over a difficult spot and stabilize it in one season. It is not a running or spreading grass but a clump former and using it as a ground cover will require multiple plantings; it will not colonize quickly.
- Height 12-16 inches
- Spacing: 18-24″ inches (45 cm)
- Sun: Full sun
- Hardiness: USDA zone 4
- Speed of growth: Slow
- Propagation: Easiest by division in spring but it does grow from seed
- Flowering: typical insignificant grass but production from mid-summer
- Damp soils are best
Pronunciation: Molinia (moh-LIN-ee-ah) caerulea (ser-OO-lee-ah) Surprisingly enough for a grass that tolerates damp ground, it is also a drought tolerant species. A single weekly watering will keep it alive (but not thriving) Note that this survival means that it has to be planted where it likes to live – mostly damp, acidic soils and that it will survive some abuse and weather swings.
If you plant it in the full sun in poor dry soils, it is not going to live very long in that it is not a dryland plant to begin with.
Not only does this plant do well as a ground cover, there are those who love to use it in damp container growing areas (like sunken water gardens or bogs).
The variegated variety (pictured) is most often used in formal containers or small bog gardens.